TM8100 Service Manual TM8000/TM8100 Mobile Radio Manual/MM8100 02 00 812_TM8100 MM8100 812

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Contents
Preface
Chapter 1. Description of Radio
Chapter 2. Servicing of Radio

TM8000 mobiles

TM8100 Mobile Radio

Service Manual

MM8100-02-00-812 Version 3.00

May 2004 © Tait Electronics Limited

2TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Contact Information

Tait Radio Communications http://www.taitworld.com

Corporate Head Office

New Zealand

Tait Electronics Ltd

P.O. Box 1645

Christchurch

New Zealand

E-mail (Sales): sales@taitworld.com

Technical Support:

E-mail: support@taitworld.com

Website: http://support.taitworld.com

Tait Oceania

New Zealand

Tait Communications Ltd

E-mail: headoffice@tcl.tait.co.nz

Australia

Tait Electronics (Aust) Pty Ltd

E-mail: australia@taitworld.com

Tait Europe

Regional Head Office: United Kingdom

Tait Mo b i l e Radio L t d

E-mail: teusales@tait.co.uk

Latin America

Tait La t i n A m er ica

E-mail: latinamerica@taitworld.com

Tait North America

Regional Head Office:

United States of America

Tait North America Inc

E-mail: usa@taitworld.com

Canada

Tait North America Inc

E-mail: canada@taitworld.com

Tait North Asia

Regional Head Office: Hong Kong

Tait Mobile Radio (Hong Kong) Ltd

E-mail: hongkong@taitworld.com

Beijing

Tait Mobile Radio (Hong Kong) Ltd

E-mail: beijing@taitworld.com

Tait South Asia

Regional Head Office: Singapore

Tait Electronics (Far East) Pte Ltd

E-mail: singapore@taitworld.com

Thailand

Ta i t M o b il e Ra d i o L t d

E-mail: thailand@taitworld.com

Note

For the addresses and telephone numbers of

the above regional offices refer to the

TaitWorld website.

TM8100 Mobile Radio Service Manual 3

May 2004 © Tait Electronics Limited

Tait General Software Licence Agreement

This legal document is an Agreement between

you (the “Licensee”) and Tait Electronics

Limited (“Tait”). By using any of the Software

or Firmware items prior-installed in the

related Tait product, included on this CD or

downloaded from the Tait website,

(hereinafter referred to as “the Software or

Firmware”) you agree to be bound by the

terms of this Agreement. If you do not agree

to the terms of this Agreement, do not install

and use any of the Software or Firmware.

If you install and use any of the Software or

Firmware that will be deemed to be

acceptance of the terms of this licence

agreement.

The terms of this agreement shall apply

subject only to any express written terms of

agreement to the contrary between Tait and

the Licensee.

Licence

TAIT GRANTS TO YOU AS LICENSEE THE NON-

EXCLUSIVE RIGHT TO USE THE SOFTWARE OR

FIRMWARE ON A SINGLE MACHINE PROVIDED

YOU MAY ONLY:

1. COPY THE SOFTWARE OR FIRMWARE INTO

ANY MACHINE READABLE OR PRINTED FORM

FOR BACKUP PURPOSES IN SUPPORT OF YOUR

USE OF THE PROGRAM ON THE SINGLE MACHINE

(CERTAIN PROGRAMS, HOWEVER, MAY INCLUDE

MECHANISMS TO LIMIT OR INHIBIT COPYING,

THEY ARE MARKED “COPY PROTECTED”),

PROVIDED THE COPYRIGHT NOTICE MUST BE

REPRODUCED AND INCLUDED ON ANY SUCH

COPY OF THE SOFTWARE OR FIRMWARE;

AND / OR

2. MERGE IT INTO ANOTHER PROGRAM FOR

YOUR USE ON THE SINGLE MACHINE (ANY

PORTION OF ANY SOFTWARE OR FIRMWARE

MERGED INTO ANOTHER PROGRAM WILL

CONTINUE TO BE SUBJECT TO THE TERMS AND

CONDITIONS OF THIS AGREEMENT).

THE LICENSEE MAY NOT DUPLICATE, MODIFY,

REVERSE COMPILE OR REVERSE ASSEMBLE ANY

SOFTWARE OR FIRMWARE IN WHOLE OR PART.

Title to Software

THIS AGREEMENT DOES NOT CONSTITUTE A

CONTRACT OF SALE IN RELATION TO THE

SOFTWARE OR FIRMWARE SUPPLIED TO THE

LICENSEE. NOT WITHSTANDING THE LICENSEE

MAY OWN THE MAGNETIC OR OTHER PHYSICAL

MEDIA ON WHICH THE SOFTWARE OR

FIRMWARE WAS ORIGINALLY SUPPLIED, OR HAS

SUBSEQUENTLY BEEN RECORDED OR FIXED, IT IS

A FUNDAMENTAL TERM OF THIS AGREEMENT

THAT AT ALL TIMES TITLE AND OWNERSHIP OF

THE SOFTWARE OR FIRMWARE, WHETHER ON

THE ORIGINAL MEDIA OR OTHERWISE, SHALL

REMAIN VESTED IN TAIT OR THIRD PARTIES

WHO HAVE GRANTED LICENCES TO TAIT.

Term and Termination

THIS LICENCE SHALL BE EFFECTIVE UNTIL

TERMINATED IN ACCORDANCE WITH THE

PROVISIONS OF THIS AGREEMENT. THE LICENSEE

MAY TERMINATE THIS LICENCE AT ANY TIME BY

DESTROYING ALL COPIES OF THE SOFTWARE OR

FIRMWARE AND ASSOCIATED WRITTEN

MATERIALS. THIS LICENCE WILL BE TERMINATED

AUTOMATICALLY AND WITHOUT NOTICE FROM

TAIT IN THE EVENT THAT THE LICENSEE FAILS TO

COMPLY WITH ANY TERM OR CONDITION OF

THIS AGREEMENT. THE LICENSEE AGREES TO

DESTROY ALL COPIES OF THE SOFTWARE OR

FIRMWARE AND ASSOCIATED WRITTEN

MATERIALS IN THE EVENT OF SUCH

TERMINATION.

Limited Warranty

THE SOFTWARE OR FIRMWARE IS SUPPLIED BY

TAIT AND ACCEPTED BY THE LICENSEE “AS IS”

WITHOUT WARRANTY OF ANY KIND EITHER

EXPRESSED OR IMPLIED, INCLUDING BUT NOT

BEING LIMITED TO ANY IMPLIED WARRANTIES AS

TO MERCHANTABILITY OR FITNESS FOR ANY

PARTICULAR PURPOSE. THE LICENSEE

ACKNOWLEDGES THAT THE SOFTWARE OR

FIRMWARE IS USED BY IT IN BUSINESS AND

ACCORDINGLY TO THE MAXIMUM EXTENT

PERMITTED BY LAW NO TERMS OR WARRANTIES

WHICH ARE IMPLIED BY LEGISLATION SHALL

APPLY TO THIS AGREEMENT. TAIT DOES NOT

WARRANT THAT THE FUNCTIONS CONTAINED

IN THE SOFTWARE OR FIRMWARE WILL MEET

THE LICENSEE’S REQUIREMENTS OR THAT THE

OPERATION OF THE SOFTWARE OR FIRMWARE

WILL BE UNINTERRUPTED OR ERROR-FREE.

4TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Exclusion of Liability

TAIT’S ENTIRE LIABILITY AND THE LICENSEE’S

EXCLUSIVE REMEDY SHALL BE THE FOLLOWING:

1. IN NO CIRCUMSTANCES SHALL TAIT BE

UNDER ANY LIABILITY TO THE LICENSEE, OR

ANY OTHER PERSON WHATSOEVER, FOR ANY

DIRECT OR CONSEQUENTIAL DAMAGE ARISING

OUT OF OR IN CONNECTION WITH ANY USE OR

INABILITY OF USING THE SOFTWARE OR

FIRMWARE.

2. TAIT WARRANTS THE OPERATION OF THE

SOFTWARE OR FIRMWARE ONLY WITH THE

OPERATING SYSTEM FOR WHICH IT WAS

DESIGNED. USE OF THE SOFTWARE OR

FIRMWARE WITH AN OPERATING SYSTEM

OTHER THAN THAT FOR WHICH IT WAS

DESIGNED MAY NOT BE SUPPORTED BY TAIT,

UNLESS OTHERWISE EXPRESSLY AGREED BY

TAIT.

General

THE LICENSEE CONFIRMS THAT IT SHALL

COMPLY WITH THE PROVISIONS OF LAW IN

RELATION TO THE SOFTWARE OR FIRMWARE.

Law and Jurisdiction

THIS AGREEMENT SHALL BE SUBJECT TO AND

CONSTRUED IN ACCORDANCE WITH

NEW ZEALAND LAW AND DISPUTES BETWEEN

THE PARTIES CONCERNING THE PROVISIONS

HEREOF SHALL BE DETERMINED BY THE NEW

ZEALAND COURTS OF LAW. PROVIDED HOWEVER

TAIT MAY AT ITS ELECTION BRING PROCEEDINGS

FOR BREACH OF THE TERMS HEREOF OR FOR

THE ENFORCEMENT OF ANY JUDGEMENT IN

RELATION TO A BREACH OF THE TERMS HEREOF

IN ANY JURISDICTION TAIT CONSIDERS FIT FOR

THE PURPOSE OF ENSURING COMPLIANCE WITH

THE TERMS HEREOF OR OBTAINING RELIEF FOR

BREACH OF THE TERMS HEREOF.

No Dealings

THE LICENSEE MAY NOT SUBLICENSE, ASSIGN OR

TRANSFER THE LICENCE OR THE PROGRAM

EXCEPT AS EXPRESSLY PROVIDED IN THIS

AGREEMENT. ANY ATTEMPT OTHERWISE TO

SUBLICENSE, ASSIGN OR TRANSFER ANY OF THE

RIGHTS, DUTIES OR OBLIGATIONS HEREUNDER

IS VOID.

No Other Terms

THE LICENSEE ACKNOWLEDGES THAT IT HAS

READ THIS AGREEMENT, UNDERSTANDS IT AND

AGREES TO BE BOUND BY ITS TERMS AND

CONDITIONS. THE LICENSEE FURTHER AGREES

THAT SUBJECT ONLY TO ANY EXPRESS WRITTEN

TERMS OF AGREEMENT TO THE CONTRARY

BETWEEN TAIT AND THE LICENSEE THIS IS THE

COMPLETE AND EXCLUSIVE STATEMENT OF THE

AGREEMENT BETWEEN IT AND TAIT IN

RELATION TO THE SOFTWARE OR FIRMWARE

WHICH SUPERSEDES ANY PROPOSAL OR PRIOR

AGREEMENT, ORAL OR WRITTEN AND ANY

OTHER COMMUNICATIONS BETWEEN THE

LICENSEE AND TAIT RELATING TO THE

SOFTWARE OR FIRMWARE.

TM8100 Mobile Radio Service Manual 5

May 2004 © Tait Electronics Limited

Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Scope of Service Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Summary of Service Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Enquiries and Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Updates of Manual and Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Disclaimer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Typographical Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Associated Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Publication Record . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

List of Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Chapter 1 Description of Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

3 Circuit Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Chapter 2 Servicing of Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

4 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

5 Servicing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

6 Disassembly and Re-assembly of Radio . . . . . . . . . . . . . . . . . . . . . . 125

7 Servicing of Control Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8 Servicing of Main Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

9 Diagnosis of Faults on Main Board . . . . . . . . . . . . . . . . . . . . . . . . . 171

6TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Preface

Scope of Service Manual

This manual provides information to service technicians for carrying out

level-1 and level-2 repairs of TM8100 mobile radios. Level-1 repairs

entail the replacement of faulty parts and circuit boards; level-2 repairs

entail the repair of circuit boards, with the exception of certain special

items on the boards. The manual does not cover level-3 repairs, which

entail the repair of the special items. The servicing procedures are

moreover limited to the control head and radio body of TM8100 mobile

radios. Servicing of all accessories associated with the radio is covered in

the accessories manual.

Summary of Service Manual

The service manual is divided into two chapters. A description of the

radio is given in Chapter 1. After an introductory section, an illustrated

parts breakdown is given for the radio. This is followed by a description

of the principles of operation of the radio and the functioning of the

circuitry.

The servicing procedures are given in Chapter 2. General information

is given first, followed by the full sequence of tasks required to service a

particular radio. The chapter concludes with additional details for

certain tasks, namely, disassembly and re-assembly of the radio, servicing

of the control head, general information on the servicing of the main

circuit board, and the diagnosis of faults on the main circuit board.

TM8100 Mobile Radio Service Manual 7

May 2004 © Tait Electronics Limited

Enquiries and Comments

Any enquiries regarding this manual or the equipment that it describes,

as well as any comments, suggestions and notifications of errors, should

be addressed by e-mail to Technical Support (support@taitworld.com)

or to the Technical Support Manager, Tait Electronics Limited, PO Box

1645, Christchurch, New Zealand. Orders for this manual can be placed

with your Tait Dealer.

Updates of Manual and Equipment

In the interests of improving the performance, reliability or servicing of

the equipment, Tait Eletcronics Limited reserves the right to upgrade the

equipment or update this manual or both without prior notice.

All information contained in this manual is the property of Tait

Electronics Limited. All rights are reserved. This manual may not, in

whole or in part, be copied, photocopied, reproduced, translated, stored,

or reduced to any electronic medium or machine-readable form,

without prior written permission from Tait Electronics Limited. All

trade names referenced are the service mark, trade mark, or registered

trade mark of the respective manufacturers.

Disclaimer

There are no warranties extended or granted by this manual. Tait

Electronics Limited accepts no responsibility for damage arising from use

of the information contained in the manual or of the equipment and

software it describes. It is the responsibility of the user to ensure that use

of such information, equipment and software complies with the laws,

rules and regulations of the applicable jurisdictions.

8TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Typographical Conventions

Conventions In this manual a special font is used for the names of certain hardware-

related and software-related elements. Details of these elements are given

in the tables below. The font used is Helvetica Narrow, with small

capitals for hardware-related and italics for software-related elements. In

essence this typographical convention is used to distinguish long or

cryptic names of elements from the ordinary text of the document.

Sequences of GUI

elements For indicating the selection of a sequence of GUI (graphical user

interface) elements, the convention illustrated by the following example

is applied: Select “Start” > “Programs” > “Tait Programming Applications” >

“TM8100 Programming Application” means: Select the “Start” menu, then

select the “Programs” option from the list that appears, then the “Tait

Programming Applications” option from the second list, and finally the

“TM8100 Programming Application” option from the third list that appears.

Hardware-related elements

Convention Usage Examples

“SMALL CAPS QUOTES”Labelled hardware

items and settings

Connect the cable to the “NODE” port.

Set the switch to the “TX/PTT” position.

SMALL CAPS Electrical signals Check the signal DIG CDC2 LRCK at pin 10 of

IC205.

Unlabelled hardware

items and settings

Remove the VCO TOP and SYN TOP cans.

Press the ON/OFF key.

Software-related elements

Convention Usage Examples

“Italics Quotes” Labelled GUI elements Note the values listed in the “AGC Delta Gain

Values” field.

Italics Unlabelled GUI elements

and displayed or typed text

Click the Close button.

The message node is not running is displayed.

Bold italics Variables in displayed or

typed text or GUI items

Enter the CCTM command 304 ccc, where

ccc is the DAC value of the clamp current.

TM8100 Mobile Radio Service Manual 9

May 2004 © Tait Electronics Limited

Alert notices Alert notices that appear in the manual are selected from whichever of

the following are appropriate. These alert notices are in accordance with

the ANSI definitions.

Warning!! This alert notice is used when there is a

potential risk of death or serious injury.

Caution This alert notice is used when there is a risk of

minor to moderate injury to people.

Important This alert notice is used to warn about the risk of

equipment damage or malfunction.

Note This alert notice is used to highlight information that is

required to ensure that procedures are performed correctly.

10 TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Associated Documentation

Basic manuals Together with this service manual, the following manuals are of concern

to service technicians. The pair of digits in the third field of the

document product code indicates the language of the document — 00

indicates an English and 03 a multi-lingual document.

MM8100-00-03-804

TM8100 mobile radio — User’s guide

MMAA00-00-00-812

TM8100 mobile radio — Accessories manual

PCB information

packages Information on the circuit boards is supplied in the following separate

documents. The information consists of the BOMs (bills of materials),

grid reference indexes, PCB layouts, and circuit diagrams.

MMAB12-B1-00-814

Main board (B1) — PCB information package

MMAB12-D1-00-814

Main board (D1) — PCB information package

MMAB12-H5-00-814

Main board (H5/H6) — PCB information package

MMAC20-00-00-814

Control-head board (two-digit display) — PCB information package

MMAC50-00-00-814

Control-head board (one-digit display) — PCB information package

3DK manuals The following manuals are mainly of concern to third-party developers.

The manuals are supplied in soft-copy form on a 3DK (third-party

developer’s kit) resource CD.

MMAA30-01-00-807

TM8000 3DK hardware developer’s kit — Application manual

MMAA30-02-00-429

TM8000 3DK application board — Software programmer’s manual

MMAA30-02-00-812

TM8000 3DK application board — Service manual

MM8100-00-00-441

TM8100 Computer-controlled data interface — Protocol definition

TM8100 Mobile Radio Service Manual 11

May 2004 © Tait Electronics Limited

Publication Record

Version Publication date Amended sections and pages

1.00 September 2003 First release — includes information for level-1

repairs only

2.00 March 2004 Second release — information for level-2 repairs

added

3.00 May 2004 Third release — information for TM8110 radio

and D1 band added

12 TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

List of Acronyms

3DK Third-party Developer’s Kit

ACP Adjacent Channel Power

ADC Analogue-to-digital Converter

AGC Automatic Gain Control

ALC Automatic Level Control

ASC Accredited Service Centre

BOM Bill of Materials

CCTM Computer-controlled Test Mode

CODEC Coder-decoder

CSO Customer Service Organisation

CTCSS Continuous-tone-controlled Subaudible Signalling

DAC Digital-to-analogue Converter

DSP Digital Signal Processor

DTMF Dual-tone Multi-frequency

ESD Electrostatic Discharge

FCL Frequency Control Loop

FE Front-end

FPGA Field-programmable Gate Array

GPS Global Positioning System

GUI Graphical User Interface

IPN Internal Part Number

IF Intermediate Frequency

IQ In-phase and Quadrature

ISC International Service Centre

LCD Liguid-crystal Display

LED Light-emitting Diode

LNA Low-noise Amplifier

LO Local Oscillator

LPF Low-pass Filter

PA Power Amplifier

PLL Phase-locked Loop

PTT Press-to-talk

RSSI Received Signal Strength Indication

SFE Software Feature Enabler

SMD Surface-mount Device

SMT Surface-mount Technology

SMPS Switch-mode Power Supply

SPI Serial Peripheral Interface

TCXO Temperature-compensated Crystal Oscillator

TEL Tait Electronics Limited

UI User Interface

VCO Voltage-controlled Oscillator

VCXO Voltage-controlled Crystal Oscillator

TM8100 Mobile Radio Service Manual Description of Radio 13

May 2004 © Tait Electronics Limited

TM8000 mobiles

Chapter 1

Description of Radio

14 Description of Radio TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Chapter 1 Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.1 TM8100 Mobile Radio System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1.2 Radio Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.3 Control Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

1.4 Repair Levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

1.5 Product Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

1.6 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2 General Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.1 Illustrated Parts Breakdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.2 Architecture of Radio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

2.3 Operation of Control-head Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

2.4 Operation in Receive Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

2.5 Operation in Transmit Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

3 Circuit Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

3.1 Control-head board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

3.2 Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

3.3 Receiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

3.4 Frequency Synthesizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

3.5 Frequency Control Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

3.6 CODEC and Audio Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

3.7 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

3.8 Interface Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

TM8100 Mobile Radio Service Manual Introduction 15

May 2004 © Tait Electronics Limited

1 Introduction

Scope of Section This section introduces the TM8100 mobile radio system. There are six

subsections covering the following aspects:

■introduction to items that make up system

■additional information on radio body

■additional information on control head

■repair levels that govern servicing of radio

■explanation of product codes for radio body and control head

■general specification for TM8100 radios

The radio body and control head are the principal items of the system

and are the prime concern of this service manual.

1.1 TM8100 Mobile Radio System

Main Items of System The TM8100 mobile radio system is a high-performance

microprocessor-controlled transceiver with a comprehensive range of

accessories. The system is designed primarily for installation in vehicles

but can also be used in desktop, remote-monitoring and similar

applications. The system consists of the following items:

■radio body

■control head

■audio accessories

■mounting for radio

■desktop power supply (optional)

Separate calibration and programming applications are used to calibrate

and program the radio. The service manual covers the servicing of the

radio body and control head only. The accessories manual covers

servicing of all the remaining items.

Radio Body The radio body contains the transmitter, receiver and microprocessor

circuitry. The radio body also allows for the fitting of an internal options

board to provide additional functions. There are three standard external

connectors on the radio body: an RF connector, power connector, and

auxiliary connector. If an internal options board is fitted, there might or

might not be an associated external options connector. The auxiliary

and external options connectors allow for the connection of various

external devices.

16 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 1.1 Illustrations of the TM8115 radio showing both the front and rear

TM8100 Mobile Radio Service Manual Introduction 17

May 2004 © Tait Electronics Limited

Control Head The control head is attached to the radio body. There is a choice of three

control heads:

■two-digit-display control head

■one-digit-display control head

■blank control head

The control heads with a display provide an interface with the radio user

and include a socket for the connection of a microphone. (Aside from

the number of characters displayed, there are no other differences

between these two control heads.) The blank control head has no UI

(user interface) but has a single external connector called the

programming connector; this is typically used for monitoring purposes.

For calibrating and programming the radio, the control head is connected

(via the microphone or programming connector as appropriate) to the

PC on which the calibration and programming applications are installed.

Designations The designation of the radio depends on which control head is attached

to the radio body:

■TM8115 : two-digit-display control head

■TM8110 : one-digit-display control head

■TM8105 : blank control head

Illustrations of the TM8115 radio are given in Figure 1.1 and illustrations

of the TM8110 and TM8105 in Figure 1.2.

Audio Accessories One or more audio accessories may be connected to the control head

and radio body. A microphone is the accessory usually required; other

accessories that are available are a handset, high-power remote speaker,

and hands-free kit. Various external devices may also be connected. The

user’s guide and accessories manual describe the audio accessories.

Installation Kits and

Desktop Power Supply The mounting hardware for the radio is in the form of a U-cradle. It is

supplied in an installation kit and provides for the installation of the radio

in a vehicle. Alternatively, the radio might be needed for desktop use, in

which case a desktop power supply is required. Tait desktop power

supplies include the parts needed to mount the radio. The user’s guide

and accessories manual describe the installation kit.

Block Diagrams

of System The block diagrams of Figure 1.3 to Figure 1.5 illustrate possible

configurations of the radio system. Figure 1.3 and Figure 1.4 show

example installations of the TM8110 or TM8115 radio in a vehicle and

on a desktop. Figure 1.5 shows an example of the TM8105 radio (with

blank control head) installed in a vehicle. Different audio accessories are

shown connected to the radio. The hands-free kit is connected to the

auxiliary connector, and the remote speaker to the power connector.

The accessories that may be connected to the microphone connector

include the rugged microphone, as well as a DTMF (dual-tone multi-

frequency) microphone, desktop microphone, and handset.

18 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 1.2 Illustration of the front of the TM8105 and TM8110 radios

TM8100 Mobile Radio Service Manual Introduction 19

May 2004 © Tait Electronics Limited

Figure 1.3 Block diagram of an example installation in a vehicle of a radio with a user interface

MICROPHONE

CONNECTOR

MICRO-

PHONE

HANGER

PLATE MOUNTING

CONTROL

HEAD RADIO BODY

RADIO SYSTEM

HANDS-

FREE

KIT

HIGH-

POWER

REMOTE

SPEAKER

POWER

CONNECTOR

AUXILIARY

CONNECTOR

EXTERNAL OPTIONS

CONNECTOR

EXTERNAL

DEVICE

VEHICLE

BATTERY

FUSES

RF ANTENNA

20 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 1.4 Block diagram of an example desktop installation of a radio with a user interface

MICROPHONE

CONNECTOR

HANDSET

DESKTOP

MICRO-

PHONE

RADIO SYSTEM

DESKTOP POWER SUPPLY

CONTROL

HEAD RADIO BODY

POWER

CONNECTOR

AUXILIARY

CONNECTOR

EXTERNAL OPTIONS

CONNECTOR

CONNECTOR RF ANTENNA

EXTERNAL

DEVICE

BACK-UP

BATTERY

AC MAINS

TM8100 Mobile Radio Service Manual Introduction 21

May 2004 © Tait Electronics Limited

1.2 Radio Body

Main, Digital and

Internal Options Boards The radio body consists of a rectangular case — or chassis — with a lid.

The chassis houses a main board with the receiver and transmitter

circuitry, and a digital board with the microprocessor that controls the

radio. There are different main boards available covering different

frequency bands and with different RF performances; refer to the

product codes in Figure 1.8. The digital board is reflow-soldered to the

main board. There is space in the lid for an optional internal options

board. The essentials of the arrangement are illustrated in the block

diagram of Figure 1.6.

Main-board Assembly The rear edge of the main board is attached to a heat-transfer block. The

block is in thermal contact with the rear of the case, where there are

cooling fins for heat dissipation. Heat from the output stage of the

transmitter is conducted via the heat-transfer block to the rear and

radiated from the cooling fins. (The lower surface of the case is ridged

to augment the dissipation of heat.) The RF, auxiliary and power

connectors are fixed to the rear of the main board. They project through

apertures in the heat-transfer block and the rear of the case. The main

board, digital board, and heat-transfer block constitute a separate unit

called the main-board assembly.

Internal Options Boards Either Tait-designed or custom internal options boards may be fitted in

the radio body. Full details of the boards are given in the accessories

and 3DK manuals. Any internal options board that is fitted might or

might not include an external options connector. If included, the

connector will project through an aperture in the rear of the lid. If there

is no connector, the aperture is sealed with a bung.

Internal Connections There are three sets of internal connections to the main board; these use

the following connectors:

■factory connector

■control-head connector

■internal options connector

The factory connector is for Factory use only. The control-head

connector is on the front edge of the main board; it is used to connect a

control-head loom from the control head to the main board. The

internal options connector is required when an internal options board is

fitted; it is used to connect an options loom between the two boards.

22 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 1.5 Block diagram of an example installation in a vehicle of a radio with a blank control

head

EXTERNAL

DEVICE

PROGRAMMING

CONNECTOR

MOUNTING

BLANK

CONTROL

HEAD RADIO BODY

RADIO SYSTEM

VEHICLE

BATTERY

POWER

CONNECTOR

AUXILIARY

CONNECTOR

EXTERNAL OPTIONS

CONNECTOR

EXTERNAL

DEVICE

EXTERNAL

DEVICE

FUSES

RF ANTENNA

TM8100 Mobile Radio Service Manual Introduction 23

May 2004 © Tait Electronics Limited

1.3 Control Head

Introduction The control head clips securely to the front of the radio body. The

control-head loom between the two is enclosed in the space between

them. For badging and branding purposes there are both a logo and a

label for the product model code on the front panel. The control head

may also be left unbadged. For the control heads with UI, the essential

features are shown in the block diagram of Figure 1.6.

Control Heads with UI The front panel of the control heads with UI is fitted with the controls

and indicators needed by the radio user; these comprise:

■LCD (liquid-crystal display) screen

■indicator LEDs (light-emitting diodes)

■volume control

■ON/OFF key

■function keys

■channel-selection keys

In addition, there are the microphone connector and an internal speaker.

The necessary circuitry for the above items is mounted on a control-head

board fitted behind the front panel. The volume-control potentiometer

is fixed to the board; so is a control-head connector, which is used for

the control-head loom between the control head and radio body.

Options for Control

Heads with UI The control heads with UI allow for an optional concealed microphone

or the use of a dynamic microphone. (A concealed microphone is fitted

behind the front panel next to the speaker.) With either option a separate

circuit board is required for the microphone. This board is connected to

the control-head board by means of two connectors; the plugs of the

connectors are mounted on the latter board and the sockets on the

former. Full details of the optional microphones and circuit board are

given in the accessories manual.

Blank Control Head The blank control head has none of the features of the control heads with

UI. The front panel of the blank control head is fitted only with the

single programming connector. The control-head loom is permanently

fixed to the rear of the programming connector. The space inside the

control head can be used for the fitting of an optional third-party circuit

board, but is otherwise empty.

24 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 1.6 Block diagram of the radio body and control head of a radio with a user interface

MICROPHONE

CONNECTOR

DISPLAY

AND LEDs

FUNCTION KEYS

AND CHANNEL-

SELECTION KEYS

VOLUME

CONTROL

ON/OFF KEY

SPEAKER

CONCEALED

MICROPHONE

(OPTIONAL)

CONTROL HEAD

CONTROL-HEAD

BOARD

CIRCUIT

BOARD FOR

OPTIONAL

MICROPHONES

SPEAKER

LEADS

MICROPHONE

LEADS

CONNECTORS

FOR OPTIONAL

BOARD

PADS

SPEAKER

CONNECTOR

CONTROL-HEAD

CONNECTOR

FACTORY

CONNECTOR

(FACTORY ONLY)

CONTROL-HEAD

CONNECTOR

CONTROL-

HEAD

LOOM

RADIO BODY

MAIN BOARD

DIGITAL BOARD

(MOUNTED ON

MAIN BOARD)

OPTIONS

BOARD

(OPTIONAL)

EXTERNAL OPTIONS

CONNECTOR

POWER

CONNECTOR

AUXILIARY

CONNECTOR

RF CONNECTOR

INTERNAL

OPTIONS

CONNECTOR

OPTIONS

LOOM

TM8100 Mobile Radio Service Manual Introduction 25

May 2004 © Tait Electronics Limited

1.4 Repair Levels

Introduction The repairs that can be carried out on the radio are grouped into

categories — or levels — of increasing complexity. This manual covers

two repair levels:

■level-1 repairs

■level-2 repairs

The repairs included at each level are defined below. The specific repair

skills and resources needed for each repair level are discussed in Chapter

2. By resources is meant tools and equipment, spares kits, and the type

of access to the TaitWorld website.

Level-1 Repairs There are three types of level-1 repair:

■replacement of control-head board

■replacement of main-board assembly

■replacement of other parts

The last-named parts include the connectors and volume-control

potentiometer on the control-head board, but not the connectors on the

main board.

Level-2 Repairs There are two types of level-2 repair:

■repair of control-head board

■repair of main-board assembly, excluding special items

These repairs entail the replacement of faulty SMT (surface-mount

technology) components on the boards, as well as the connectors on the

main board. The special items are the digital board and certain

components on the main board; the details are given in Chapter 2.

(Repairs of the special items are level-3 repairs.)

Service Centres The service centres that carry out repairs of the radios can be divided into

three categories:

■Dealers and Customers with appropriate facilities

■ASCs, including CSOs (Customer Service Organisations)

■TEL and ISC

ASCs (accredited service centres), the ISC (International Service Centre)

and TEL (Tait Electronics Limited) may carry out both level-1 and

level-2 repairs. These are moreover the only service centres that may

repair a radio that is still under warranty — any repair by a non-

accredited service centre will void the warranty. After the expiry of the

warranty, Dealers and Customers with appropriate facilities may also

carry out level-1 repairs, but are strongly advised not to attempt level-2

repairs. Details of the process by which service centres may achieve

accreditation are given in Chapter 2.

26 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Restrictions Regarding

Level-3 Repairs Only TEL and the ISC should carry out level-3 repairs. The level of

technology employed in the TM8100 generation of radios is an order of

magnitude greater than in earlier generations. This greater sophistication

demands special equipment and techniques for level-3 repairs. Although

other service centres are strongly advised not to attempt such repairs,

those with sufficient resources and skilled technicians may wish to do so.

These service centres should contact Technical Support for assistance and

for the necessary documentation. TEL does not offer accreditation for

level-3 repairs to any service centres other than the ISC.

1.5 Product Codes

Introduction This subsection describes the product codes used to identify different

products of the mobile radio product line. The product-code scheme in

general is first explained, and then the product codes for the radio body

and control head in particular. The purpose is solely to enable service

technicians to identify the radio body and control head of a radio that has

been delivered for repair.

Figure 1.7 Scheme for the product codes assigned to products of the mobile radio product line

TMabcc ddee PRODUCT IN MOBILE RADIO PRODUCT LINE

Product identifiers

Options (radio body only) (digits and letters)

Part 2 of product identifier (digits and letters)

Part 1 of product identifier (digits only)

Category of product

A = accessory

B = radio body

C = control head

Product family

A = TM8105, TM8110 and TM8115

Product line

M = mobile radios

TM8100 Mobile Radio Service Manual Introduction 27

May 2004 © Tait Electronics Limited

Limitations on Use

of Product Codes The product codes discussed in this subsection are those in use at the time

of publication. For up-to-date information refer to the TaitWorld

website. The explanations of the product codes are to aid identification

only, and are not to be used as the basis for sales orders. There are two

reasons for this: Firstly, an arbitrarily-constructed product code might

apply to a product that, for compliance reasons, is restricted to certain

markets. Secondly, a product with such a product code might not even

exist.

General Scheme for

Product Codes Individual products of the mobile radio product line are identified by

product codes with the format:

TMabcc–ddee

where a and b are uppercase letters representing the product family and

category of product respectively, and cc, dd and ee are characters that

identify the specific product. The characters ee are applicable to the

radio body only and identify different options. The product code

scheme is summarised in Figure 1.7.

Figure 1.8 Scheme for the product codes currently in use for the radio body

TMABab ccdd

D1 = 220 to 270 MHz

RADIO BODY

Radio options

00 = no options

Frequency band

B1 = 136 to 174 MHz

H5 = 400 to 470 MHz

H6 = 450 to 530 MHz

RF performance

2 = 25 W

Architecture of digital board

3 = 25 W (trigger-base)

1 = conventional analogue

28 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Product Families

and Categories Examples of different product families within the mobile radio product

line are the T700, T2000 and TM8100 radios. The TM8100 family is

however the first to which the above product-code scheme applies.

Examples of different product categories are radio bodies, control heads,

and accessories. These are the only categories identified to date. The

product codes for the radio body and control head are discussed below;

those for the accessory items are described in the accessories manual.

Product Codes

for Radio Body The product codes for the radio body have the format:

TMABab–ccdd

where a identifies the architecture of the digital board, b identifies the

RF performance, cc is the letter-digit combination identifying the

frequency band, and dd identifies any options selected. The characters

dd are set to 00 for the default radio with no options added. For

universal options available to all Customers, the digits 01 to 99 are used

for dd. For custom options implemented for particular Customers, the

letters AA to ZZ are used. The digits and letters identifying the universal

and custom options are assigned sequentially. Figure 1.8 illustrates the

product codes in use at the time of publication.

Figure 1.9 Scheme for the product codes currently in use for the control head

TMACab cc

CONTROL HEAD

Badge and branding options

0T = Tait

0U = unbadged

Options for control head

0 = no options

Type of control head

1 = blank control head

2 = two-digit-display control head

5 = one-digit-display control head

TM8100 Mobile Radio Service Manual Introduction 29

May 2004 © Tait Electronics Limited

Product Codes

for Control Head The product codes for the control head have the format:

TMACab–cc

where a identifies the type of control head, b identifies any options

selected, and cc identifies badging and branding options. By type is

meant whether the control head is blank or has a user interface with a

one- or two-digit display; allowance is made for additional types in the

future. Only the digits 1 to 9 are allowed for a (0 is not used), and the

digits 0 to 9 for b; the latter is set to 0 when no options are added. Both

letters and digits may be used for cc. The default for cc is 0T; on one-

and two-digit-display control heads the Tait logo is then displayed next

to the LCD screen; the product model code TM8110 and TM8115

respectively is displayed above the speaker grille. Figure 1.9 illustrates the

product codes in use at the time of publication.

1.6 Specifications

Introduction General specifications for TM8100 radios are given in Table 1.1 and

Table 1.2. The parameter values quoted in the tables are minimum

values. These specifications are valid for the date of publication only.

The specifications will also be found on the TaitWorld website in the area

reserved for TM8000 products. The latter specifications are updated

whenever changes occur.

30 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Table 1.1 General specification for TM8100 radios — Basic, physical and environmental aspects

Parameter Values

Basic characteristics

Frequency bands:

• B1 band

• D1 band

• H5 band

• H6 band

136 to 174 MHz

216 to 266 MHz

400 to 470 MHz

450 to 530 MHz

Frequency stability ±1.5 ppm

Channel capacity (simplex or semi-duplex):

• TM8110 radio

• TM8115 radio

Channel spacing:

• Narrow

• Medium

• Wide

12.5 kHz

20 kHz

25 kHz

Power supply Between 10.8 and 16 V DC

RF connector 50 Ω BNC or miniature UHF

Interface connectors:

• Microphone connector

• Auxiliary connector

• Internal options connector

Ports:

1 serial, 1 I/O

1 serial, 3 input, 4 I/O, 1 audio tap in, 1 audio tap out

1 serial, 7 I/O, 1 audio tap in, 1 audio tap out

Physcial characteristics

Weight 1.43 kg (50.44 ounces)

Dimensions:

• Length

• Width

• Height

175 mm (6.88 inches)

160 mm (6.29 inches)

50 mm (1.97 inches)

Environmental conditions

Operating temperatures −30°C to +60°C (−22°F to +140°F)

Standards

• IP54

• MIL-STD 810C, D, E and F

(for details contact Technical Support)

Meets the requirements for sealing against:

• Dust

• Rain

Meets the requirements regarding the following aspects:

• Low pressure

• High temperature

• Low temperature

• Temperature shock

• Solar radiation

• Vibration

• Shock

• Dust

• Rain

• Humidity

• Salt fog

TM8100 Mobile Radio Service Manual Introduction 31

May 2004 © Tait Electronics Limited

Table 1.2 General specification for TM8100 radios — Transmitter and receiver

Parameter Values

Transmitter

Output power:

• Level 1 — very low

• Level 2 — low

• Level 3 — medium

• Level 4 — high

1 W

5 W

10 W

25 W

Modulation limiting:

• Narrow channel spacing

• Medium channel spacing

• Wide channel spacing

< ±2.5 kHz

< ±4 kHz

< ±5 kHz

FM hum and noise:

• Narrow channel spacing

• Medium channel spacing

• Wide channel spacing

> 33 dB

> 41 dB

> 43 dB

Conducted and radiated emissions:

• Up to 1 GHz

• Between 1 and 4 GHz

(for radio operating frequencies below 500 MHz)

• Between 1 and 12.75 GHz

(for radio operating frequencies above 500 MHz)

< −36 dBm

< −30 dBm

Audio response 300 Hz to 3 kHz (flat or with pre-emphasis)

Audio distortion < 3% at 1 kHz 60% modulation

Transmit rise time

(From the time the external PTT line is asserted to the time

when the RF output power reaches 90% of its final value)

< 10 ms

Receiver

Sensitivity < −118 dBm for 12 dB SINAD

Intermodulation > 66 dB

Spurious responses > 72 dB

Selectivity:

• Narrow channel spacing

• Medium channel spacing

• Wide channel spacing

> 65 dB

> 70 dB

> 75 dB

Hum and noise:

• Narrow channel spacing

• Medium channel spacing

• Wide channel spacing

> 40 dBm

> 41 dBm

> 43 dBm

Audio response 300 Hz to 3 kHz (flat or with de-emphasis)

Audio distortion < 3%

Receive detect time

(From the time an RF signal is first present at the antenna to

the time when the BUSY DETECT line changes state)

< 3 ms

32 Introduction TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

TM8100 Mobile Radio Service Manual General Description 33

May 2004 © Tait Electronics Limited

2 General Description

Scope of Section This section comprises a general description of the radio body and

control head of TM8100 radios. Firstly, the mechanical parts,

miscellaneous parts, and circuit boards that make up the radio are

identified and discussed. Secondly, the basic modules of the circuitry are

identified and their essential functions described. Thirdly, the operation

of the control-head circuitry is summarised. Finally, the principles of

operation of the radio are given in three separate subsections.

2.1 Illustrated Parts Breakdown

Introduction This subsection identifies all the mechanical parts, miscellaneous parts,

and circuit boards that make up the radio. The parts and circuit boards

are illustrated in three sets of figures covering respectively the control

heads with UI, the blank control head, and the radio body. The figures

are exploded-view illustrations showing how the parts and circuit boards

are assembled to build the complete radio. Accompanying the figures are

tables in which the parts identified in the figures are listed and their

details given.

Labels on Radio Before the different parts of the radio are considered, however, some

important external features are described. These are illustrated in

Figure 2.1, which shows the underside of the radio. The first feature is

the set of four labels with the following information:

■compliance information

■serial number and product code

■safety label — hot surface

■safety label — RF exposure

The two safety labels concern the high temperatures that the body of the

radio can attain in operation and exposure to RF radiation during

transmissions. Regarding the former, the figure clearly shows the

cooling fins at the rear and the ridges on the underside, which are

provided for heat dissipation.

34 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.1 Underside of the radio showing the labels and connectors on the radio body

SERIAL NUMBER AND

PRODUCT CODE

CONTROL HEAD

POWER

CONNECTOR

BUNG FOR

AUXILIARY CONNECTOR

COMPLIANCE INFORMATION

RF CONNECTOR

RADIO BODY

SAFETY LABEL

(HOT SURFACE)

SAFETY LABEL

(RF EXPOSURE)

CONTROL-HEAD SEALLEVER POINT

MOUNTING

POINTS

COVER SEAL FOR

EXTERNAL OPTIONS CONNECTOR

(BUNG IS FITTED IF THERE IS NO CONNECTOR)

TM8100 Mobile Radio Service Manual General Description 35

May 2004 © Tait Electronics Limited

Mounting Points, Seals

and Connectors Other features illustrated in Figure 2.1 are the mounting points for the

radio, the seal between the control head and radio body, and the

connectors at the rear. The last-named are:

■RF connector

■power connector

■auxiliary connector

■external options connector (optional)

A bung seals the access to the auxiliary connector when this connector

is not used. A second bung seals the aperture provided for the external

options connector when there is no internal options board with such a

connector. If an options board with a connector is installed, a cover seal

is supplied instead. Whenever the connector is not in use, the cover seal

is fitted over the connector as shown in the figure. The bungs and seals

ensure that the radio is sealed to IP54 standards.

Separation of Control

Head and Radio Body Figure 2.2 shows the control head detached from the radio body, the

control-head loom between them, and the control-head seal. The seal is

fitted to the front face of the radio body. The loom is shown still

connected to the control-head connector on the radio body. The two

points where the control head is levered off the radio body are indicated

by dot-dash-dot marks on the underside. These lever points are shown

in Figure 2.1. The control head may be attached to the radio body with

the underside of the radio body facing either up or down. Which

orientation is appropriate depends on the installation.

36 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Parts of Control

Head with UI Figure 2.3 to Figure 2.5 illustrate the parts of a control head with UI. In

the figures each relevant part is identified by an index number. In

Table 2.1 all the index numbers are listed and the corresponding details

of these parts are given. The parts of accessory items are also identified

in the figures but are not assigned index numbers. Details of such parts

are given in the accessories manual.

Exterior of

Control Head Figure 2.3 shows the exterior of the control head. Illustrated are the

front panel with the various keys and indicator LEDs, and the lens

covering the display. There is a rectangular aperture in the lens through

which the display is viewed. Depending on the type of control head, the

aperture is sized to fit either the one or the two characters displayed. An

identifying label distinguishes the control heads. Externally the control

heads differ only in this label and the lens. Also shown in Figure 2.3 are

the knob for the volume-control potentiometer and the access to the

microphone connector. The potentiometer and connector are mounted

on the control-head board inside the front panel.

Figure 2.2 Illustration showing the control head detached from the radio body

CONTROL-HEAD LOOM

RADIO BODY

CONTROL HEAD CONTROL-HEAD SEAL

TM8100 Mobile Radio Service Manual General Description 37

May 2004 © Tait Electronics Limited

Control-head Board Figure 2.4 and Figure 2.5 show the interior of the control head. The

control-head board is screwed to a space-frame that is fitted inside the

front panel. (Different boards are required for the one- and two-digit-

display control heads.) The control-head loom connected to the board

requires a female-to-female adaptor to allow connection to the radio

body. Figure 2.4 also shows the separate circuit board mounted on the

control-head board when a dynamic or concealed microphone is used.

Space-frame, Keypad

and Display The space-frame fits over the speaker, a keypad, and the LCD for the

display. The keypad is designed so that pressing any key results in contact

being made with the control-head board. There are four light pipes in

the keypad for the LEDs associated with the function keys. Light pipes

for the three STATUS LEDs, however, are moulded into the front panel.

The LCD fits in a recess in the front panel. Electrical contact between

the LCD and the control-head board is ensured by two elastomeric strips

held in place by the space-frame.

Figure 2.3 Exterior of a control head with UI

ACCESS TO

MICROPHONE

CONNECTOR

SPEAKER GRILLE

38 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.4 Interior of a control head with UI showing the space-frame and associated parts

CIRCUIT BOARD

FOR CONCEALED

AND DYNAMIC

MICROPHONES

(OPTIONAL)

TM8100 Mobile Radio Service Manual General Description 39

May 2004 © Tait Electronics Limited

Speaker and

Microphones A speaker is always fitted, although in certain installations it is not used

and therefore not connected to the control-head board. (The

connecting wires are not shown in the figures.) A cloth membrane for

the speaker is fixed to the speaker grille on the inside of the front panel.

Figure 2.5 also shows the two parts of a concealed microphone — the

microphone capsule and a rubber seal. These are fitted in a recess in the

front panel next to the speaker. The leads from the capsule are soldered

to pads on the control-head board. Before the microphone is fitted a

small hole is drilled in the recess to provide an acoustic path to the

microphone. The hole is covered by the rubber seal to ensure that the

control head remains sealed to IP54 standards. The concealed

microphone is an optional accessory like the dynamic microphone; both

are described in the accessories manual.

Table 2.1 Parts of the control heads with UI

Index Reference IPN Description Quantity

1 Figure 2.3 316-06786-xx Front panel 1

2 Figure 2.3 311-01054-xx Knob for volume-control potentiometer 1

3 Figure 2.3 312-01095-xx Lens with Tait logo (two-digit display) 1

312-01106-xx Lens with Tait logo (one-digit display)

4 Figure 2.3 365-01717-xx Label for TM8115 1

365-01745-xx Label for TM8110

5 Figure 2.4 219-02882-xx Control-head loom 1

6 Figure 2.4 240-00021-41 Female-female adaptor for control-head connector 1

7 Figure 2.4 346-10030-08 3 x 8 PT screw for control-head board 3

8 Figure 2.4 XMAC20 Control-head board (two-digit display) 1

XMAC50 Control-head board (one-digit display)

9 Figure 2.4 209-00011-xx Elastomeric strip 2

10 Figure 2.4 319-30073-xx Space-frame 1

11 Figure 2.5 252-00011-xx Speaker 1

12 Figure 2.5 307-01024-xx Speaker membrane 1

13 Figure 2.5 311-03114-xx Keypad 1

14 Figure 2.5 262-00003-xx Short light pipe 2

15 Figure 2.5 262-00004-xx Long light pipe 2

16 Figure 2.5 008-00031-xx LCD 1

Note

The characters xx in an IPN (internal part number) stand for the issue number. Items in the control head will

always be the latest issue at the time the control head is manufactured.

40 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.5 Interior of a control head with UI showing the parts remaining after the removal of the

space-frame

CAPSULE OF CONCEALED

MICROPHONE (OPTIONAL)

RUBBER SEAL FOR CONCEALED

MICROPHONE (OPTIONAL)

LIGHT PIPES

FOR STATUS LEDs

TM8100 Mobile Radio Service Manual General Description 41

May 2004 © Tait Electronics Limited

Parts of Blank

Control Head Figure 2.6 and Figure 2.7 illustrate the parts of the blank control head.

Details of the parts are summarised in Table 2.2. Figure 2.6 shows the

exterior of the control head. Illustrated are the front panel and the cover

seal for the programming connector. When the connector is not in use,

the seal is fitted to ensure that the control head is sealed to IP54 standards.

Figure 2.7 shows the interior of the control head. There is provision in

the blank control head for the fitting of a custom circuit board.

Otherwise, as shown in the figure, only the control-head loom is fitted.

The programming connector at one end of the loom is screwed to the

front panel. The female-to-female adaptor needed for connection of the

other end to the radio body is supplied as part of the loom.

Figure 2.6 Exterior of the blank control head

PROGRAMMING CONNECTOR

42 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.7 Interior of the blank control head

TM8100 Mobile Radio Service Manual General Description 43

May 2004 © Tait Electronics Limited

Parts of Radio Body Figure 2.8 to Figure 2.12 illustrate the parts of the radio body. Details of

the parts are summarised in Table 2.3. Figure 2.8 shows the two main

assemblies that make up the radio body — the lid assembly and the

chassis assembly. Also shown are the cover for the radio body and the

control-head seal detached from the chassis. The cover label shown in

the figure is permanently fixed to the cover. The screws secure the lid to

the chassis. The parts of the lid assembly and chassis assembly are shown

in the remaining figures.

Lid Assembly Figure 2.9 and Figure 2.10 show the parts of the lid assembly. Any

internal options board is mounted inside the lid, and this case is illustrated

in Figure 2.10. The main seal shown in both figures is an O-ring that

fits in a groove in the wall of the lid. This seal ensures that the lid is

properly sealed to the chassis. Figure 2.9 also shows the bung that seals

the aperture provided in the lid for an external options connector.

Figure 2.10 shows a typical large options board. A cover seal is supplied

for the board’s external options connector. The options loom connects

the options board to the internal options connector on the main board.

The latter connector is indicated in Figure 2.12.

Chassis Assembly Figure 2.11 and Figure 2.12 show the parts of the chassis assembly.

Illustrated in Figure 2.11 are the chassis and the main board, digital

board, and heat-transfer block of the main-board assembly. Also shown

are the bung for the auxiliary connector and the seal needed for the RF

connector. The screws secure the main-board assembly in the chassis.

Figure 2.12 shows the heat-transfer block detached from the main board.

All the parts associated with the block are illustrated; the principal parts

are inner and outer foam seals needed for the auxiliary connector, and a

rubber seal for the power connector. The lock washer and hexagonal nut

are supplied as integral parts of the RF connector. The screws secure the

heat-transfer block to the main board.

Table 2.2 Parts of the blank control head

Index Reference IPN Description Quantity

1 Figure 2.6 316-06786-xx Front panel of blank control head 1

2 Figure 2.6 312-01095-xx Label with Tait logo 1

3 Figure 2.6 354-01043-xx Lock-nut for programming connector 1 pair

4 Figure 2.6 362-01108-xx Cover seal for programming connector 1

5 Figure 2.6 347-00011-xx UNC 4-40 x 3/16-inch pan Pozi screw for cover seal 2

6 Figure 2.7 219-02902-xx Control-head loom for blank control head 1

7 Figure 2.7 362-01111-xx Foam seal for programming connector 1

Note

The characters xx in an IPN stand for the issue number. Items in the control head will always be the latest

issue at the time the control head is manufactured.

44 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.8 Cover, control-head seal, lid assembly, and chassis assembly of the radio body

CHASSIS ASSEMBLY

LID ASSEMBLY

TM8100 Mobile Radio Service Manual General Description 45

May 2004 © Tait Electronics Limited

Dissipation of Heat Heat needs to be dissipated from the interior of the radio body and, in

particular, from the following components on the main board:

■9V regulator

■audio PA (power amplifier)

■two RF PAs

■driver for RF PAs

These components are discussed in Section 3. The mechanisms by

which the heat is conducted away in each case are described below.

Dissipation of Heat

from Radio Interior Heat from the radio interior is conducted via the heat-transfer block to

the cooling fins at the rear, where it is radiated away. The ridged

underside of the chassis augments the dissipation of heat. The rear face

of the block is in contact with the chassis where the fins are situated. A

coating of thermal paste on the rear face ensures the necessary thermal

contact between the two surfaces. The coated area is shown in both

Figure 2.11 and Figure 2.12.

Figure 2.9 Parts of the lid assembly

46 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.10 Parts of the lid assembly with an internal options board

TYPICAL LARGE

INTERNAL OPTIONS BOARD

SCREWS FOR SECURING

INTERNAL OPTIONS BOARD OPTIONS LOOM

FOAM SEAL

COVER SEAL

LOCK-NUTSSCREWS

EXTERNAL

OPTIONS

CONNECTOR

TM8100 Mobile Radio Service Manual General Description 47

May 2004 © Tait Electronics Limited

Dissipation of Heat

from Regulator and

Audio PA

Heat from the regulator and audio PA is conducted to the underside of

the chassis via a screw boss on the floor of the chassis. The boss is in

contact with the underside of the PCB where the components are

mounted. A coating of thermal paste on the screw boss ensures the

necessary thermal contact between the boss and the PCB. The coated

area is shown in Figure 2.11.

Dissipation of Heat

from RF PAs and Driver Heat from the RF PAs and driver is conducted to the cooling fins via a

copper plate and the heat-transfer block. The copper plate is fixed to the

underside of the PCB beneath these components. It is in contact with a

large metal block projecting from the front of the heat-transfer block. A

coating of thermal paste on the plate ensures the necessary thermal

contact between the surfaces. The contact area on the heat-transfer

block is shown in Figure 2.12.

Table 2.3 Parts of the radio body

Index Reference IPN Description Quantity

1 Figure 2.8 303-23166-xx Cover 1

2 Figure 2.8 365-01712-xx Label for cover 1

3 Figure 2.8 349-02067-xx M4 x 16 screw for lid of radio body 4

4 Figure 2.8 362-01115-xx Control-head seal 1

5 Figure 2.9 312-01091-xx Lid of radio body 1

6 Figure 2.9 362-01109-xx Main seal in lid 1

7 Figure 2.9 302-50000-xx Bung for aperture for external options connector 1

8 Figure 2.11 303-11225-xx Chassis of radio body 1

9 Figure 2.11 349-02066-xx Internal M3 x 10 screw for main-board assembly 5

10 Figure 2.11 362-01113-xx Seal for RF connector 1

11 Figure 2.11 349-02067-xx External M4 x 16 screw for main-board assembly 2

12 Figure 2.11 302-50001-xx Bung for auxiliary connector 1

13 Figure 2.12 349-02066-xx M3 x 10 screw for heat-transfer block 3

14 Figure 2.12 308-13147-xx Heat-transfer block 1

15 Figure 2.12 362-01114-xx Rubber seal for power connector 1

16 Figure 2.12 354-01043-xx Lock-nut for auxiliary connector 1 pair

17 Figure 2.12 362-01112-xx Outer foam seal for auxiliary connector 1

18 Figure 2.12 362-01110-xx Inner foam seal for auxiliary connector 1

Note

The characters xx in an IPN stand for the issue number. Items in the radio body will always be the latest issue

at the time the radio body is manufactured.

48 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.11 Parts of the chassis assembly

DIGITAL BOARD

HEAT-TRANSFER

BLOCK

MAIN BOARD

MAIN-BOARD

ASSEMBLY

THERMAL PASTE

SCREW BOSS

TM8100 Mobile Radio Service Manual General Description 49

May 2004 © Tait Electronics Limited

Figure 2.12 Parts of the main-board assembly

16 15 THERMAL PASTE THERMAL PASTE

DIGITAL BOARD

LOCK WASHER OF

RF CONNECTOR

HEXAGONAL NUT OF

RF CONNECTOR

POWER

CONNECTOR

MAIN BOARD

INTERNAL OPTIONS CONNECTOR

AUXILIARY CONNECTOR

50 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.13 Block diagram of the main board of the radio body

POWER SUPPLY

MAIN

BOARD

DIGITAL BOARD

RECEIVER

FRE-

QUENCY

SYNTHE-

SIZER

TRANS-

MITTER

CODEC

AND AUDIO

CIRCUITRY

INTERFACE

CIRCUITRY

CONTROL-

HEAD

CONNECTOR

POWER

CONNECTOR

AUXILIARY

CONNECTOR

INTERNAL

OPTIONS

CONNECTOR

FACTORY

CONNECTOR

(FACTORY

ONLY)

RF CONNECTOR

DIG TX INH

SYN TX LO

SYN LOCK

SYN RX OSC

SYN RX LO1

TX RX RF

DIG RX EN

DIG SYN SPI

TX RX RF

DIG SYN EN

DIG RX EN

PSU SYS RST

+3V3

TM8100 Mobile Radio Service Manual General Description 51

May 2004 © Tait Electronics Limited

2.2 Architecture of Radio

Introduction In this subsection the architecture of the radio is described. The different

circuit modules of the control-head, main and digital boards introduced

in Subsection 2.1 (on page 33) are identified and their essential functions

are summarised. The optional circuit boards mentioned in

Subsection 2.1 are covered in other manuals.

Control Head The control heads with UI house a control-head board with the circuitry

needed for the controls and indicators on the front panel. There is

provision for an optional circuit board for use with dynamic

microphones or with a concealed microphone inside the control head.

There is also provision for the fitting of an optional third-party circuit

board in the blank control head.

Circuit Boards in

Control Head The operation of the control-head board is summarised in

Subsection 2.3 (on page 53). The circuit board for concealed and

dynamic microphones is described in the accessories manual. The fitting

of third-party circuit boards in the blank control head is discussed in the

application manual for 3DK hardware developers.

Radio Body The radio body houses a main board with the transmitter, receiver and

associated circuitry, and a digital board with the microprocessor and

associated circuitry. The digital board is reflow-soldered to the main

board. There is also provision for an internal options board to be

connected to the main board.

Circuit Boards and

Modules in Radio Body The different circuit modules of the main board are discussed below and

the operation of the circuitry is described in Subsection 2.4 (on page 54)

and Subsection 2.5 (on page 57). The different internal options boards

are discussed in the accessories manual and the 3DK manuals.

Modules of Main Board The control-head, main and digital boards, and the connectors on the

boards, are illustrated in Figure 1.6 of the previous section. Figure 2.13

is a block diagram showing the main and digital boards and the circuit

modules of the main board. These modules are:

■transmitter

■receiver

■frequency synthesizer

■CODEC (coder-decoder) and audio circuitry

■power supply

■interface circuitry

Software plays a prominent role in the functioning of the radio. For

describing the operation of the radio the software must be included with

the above modules. This is considered further below.

52 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 2.14 Architecture of the TM8100 transceiver

IF:

UHF: 45.1 MHz

VHF: 21.4 MHz

Digital

down-

converter

Squelch

Front

end

1st

Channel

LPF

Channel

LPF

RSSI

Second LO

UHF: 90.328 MHz

VHF: 42.928 MHz

Demod

Quad

Demod

AGC

Analogue-to-digital conversion

2nd IF:

64 kHz

Audio

filtering

De-

emphasis

Optional

processing

Data and signalling

decoders

Side

tones

Volume

control

Audio

Phase

locked to

TCXO

LPF

ANT

Control

Head

PWR

Mag.

PLL

Loop

filter

Loop

filter

Frequency

control

Triple-point

Equalisation

Audio

filtering

Pre-

emphasis

Optional

processing

Data and signalling

encoders

ALC Mic

PGA

Mic

FGA

Dir.

Coup. Fin Drv

/Ex

Pwr

Crtl

Ramp

control

TCXO:

13.000 MHz

VCO*

Control

Auxiliary

Head

VCXO

Bias

CUSTOM-

LOGIC

BLOCK HARDWARE

BLOCK

HARDWARE BLOCK Digital-to-analogue conversion

System interface

KEY

NOTES

(1) Noise blanker not shown

(2) VHF configuration shown*

For UHF there are separate VCOs for RX and TX

DSP

BLOCK

TM8100 Mobile Radio Service Manual General Description 53

May 2004 © Tait Electronics Limited

Operation of Radio Figure 2.14 is a simplified block diagram of the transceiver architecture

showing the hardware modules integrated with the software modules.

The same DSP (digital signal processor) device includes the software that

controls the transceiver and the software constituting the digital-signal-

processing blocks in Figure 2.14. The operation of the radio is then best

described with reference to Figure 2.14 and with a division into the

following two parts:

■operation in receive mode

■operation in transmit mode

Operational descriptions of these two parts are given in Subsection 2.4

(on page 54) and Subsection 2.5 (on page 57) respectively.

2.3 Operation of Control-head Circuitry

User Interface In this subsection the operation of the control-head circuitry is

summarised. A detailed description of the circuitry is given in Section 3

(on page 63). Control heads with UI provide a user interface consisting

of:

■seven-segment LCD

■up and down channel-selection keys

■four programmable function keys

■ON/OFF push-button key

■LED indicators

■volume control

■internal speaker

■microphone connector

The LCD displays one or two characters depending on the type of

control head. The microphone connector may also be used for the

connection of a handset or programming lead. If required, a concealed

microphone may be fitted inside the control head.

Connectors and

Circuit Boards There is an 18-way electrical interface between the control head and

radio body. The physical connection is via an 18-way loom. The control

head normally contains a single PCB assembly called the control-head

board. The differences between the boards for the one- and two-digit-

display control heads are discussed in Section 3 (on page 63). If a

dynamic microphone is used or a concealed microphone fitted, a small

circuit board must be mounted on the control-head board. The added

board has the necessary amplification, filtering and switching functions.

The internal speaker is connected to the control-head board via a lead

with a mating connector so that it can be easily disconnected.

54 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Control-head Board The control-head board does not include a microprocessor. A

synchronous bi-directional serial interface provides communication of

key status, LCD and LED-indicator data between the radio body and the

control head. On the control-head board the serial data are converted to

or from parallel form by a number of shift registers for the keys and

indicators. For the LCD, the serial data are fed to a driver IC that

converts the serial data to a form suitable for the LCD itself. The keys

are scanned and the LCD and LED indicators updated approximately

every 50 ms.

2.4 Operation in Receive Mode

Receive Path This subsection describes the functioning of the radio in receive mode.

Detailed descriptions of the circuitry involved are given in Section 3

(on page 63). As shown in Figure 2.14, the receive path exists in the

hardware, custom-logic and DSP domains. From a functional point of

view there are three major parts:

■RF hardware

■digital base-band processing

■audio processing and signalling

These functional parts are described in detail below.

RF Hardware

Front-end Circuitry

and First IF The front-end hardware amplifies and image-filters the received RF

spectrum, then down-converts the desired channel frequency to a first

intermediate frequency IF1 of 45.1 MHz (UHF) or 21.4 MHz (VHF)

where coarse channel filtering is performed. The first LO (local

oscillator) signal is obtained from the frequency synthesizer and is

injected on the low side of the desired channel frequency for all bands.

In receive mode the modulation to the frequency synthesizer is muted.

See Subsection 2.5 (on page 57) for a description of the synthesizer. The

output of the first IF (intermediate frequency) stage is then down-

converted using an image-reject mixer to a low IF of 64 kHz.

Quadrature

Demodulator The LO for the image-reject mixer (quadrature demodulator) is

synthesized and uses the TCXO (temperature-compensated crystal

oscillator) as a reference. This ensures good centring of the IF filters and

more consistent group-delay performance. The quadrature demodulator

device has an internal frequency division of 2 so the second LO operates

at 2 x(IF1 + 64 kHz). The quadrature output from this mixer is fed to

a pair of ADCs (analogue-to-digital converters) with high dynamic range

where it is oversampled at 256 kHz and fed to the custom logic device.

TM8100 Mobile Radio Service Manual General Description 55

May 2004 © Tait Electronics Limited

Automatic Gain Control The AGC (automatic gain control) is used to limit the maximum signal

level applied to the image-reject mixer and ADCs in order to meet the

requirements for intermodulation and selectivity performance.

Hardware gain control is performed by a variable-gain amplifier within

the quadrature demodulator device driven by a 10-bit DAC (digital-to-

analogue converter). Information about the signal level is obtained from

the IQ (in-phase and quadrature) data output stream from the ADCs.

The control loop is completed within custom logic. The AGC will

begin to reduce gain when the combined signal power of the wanted

signal and first adjacent channels is greater than about –70 dBm. In the

presence of a strong adjacent-channel signal it is therefore possible that

the AGC may start acting when the wanted signal is well below

–70 dBm.

Noise Blanking

(B1 band only) For the B1 band only, noise-blanking circuitry is included. The noise

blanker removes common sources of electrical interference such as

vehicle ignition noise. The programming application allows for disabling

the noise blanker if it is not required. The noise blanker functions by

sampling the RF input to the receiver for impulse noise and momentarily

disconnecting the first LO for the duration of the impulse. The response

time of the noise blanker is very fast (tens of nanoseconds) and is shorter

than the time taken for the RF signal to pass through the front-end

hardware, so that the LO is disabled before the impulse reaches the IF

stage where it could cause crystal filter ring.

Digital Base-band Processing

Custom Logic The remainder of the receiver processing up to demodulation is

performed by custom logic. The digitised quadrature signal from the RF

hardware is digitally down-converted to a zero IF, and channel filtering

is performed at base-band. Different filter shapes are possible to

accommodate the various channel spacings and data requirements.

These filters provide the bulk of adjacent channel selectivity for narrow-

band operation. The filters have linear phase response so that good

group-delay performance for data is achieved. The filters also decimate

the sample rate down to 48 kHz. Custom logic also performs

demodulation, which is multiplexed along with AGC and amplitude

data, and fed via a single synchronous serial port to the DSP. The stream

is demultiplexed and the demodulation data used as an input for further

audio processing.

Noise Squelch The noise squelch process resides in the DSP. The noise content above

and adjacent to the voice band is measured and compared with a preset

threshold. When a wanted signal is present, out-of-band noise content

is reduced and, if below the preset threshold, is indicated as a valid

wanted signal.

56 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Received Signal

Strength Indication Received signal strength is measured by a process resident in the DSP.

This process obtains its input from the demodulator (value of RF signal

magnitude) and from the AGC (value of present gain). With these two

inputs and a calibration factor, the RF signal strength at the antenna can

be accurately calculated.

Calibration The following items within the receiver path are calibrated in the

Factory:

■front-end tuning

■AGC

■noise squelch

■RSSI (received signal strength indication)

Information on the calibration of these items is given in the on-line help

facility of the calibration application.

Audio Processing and Signalling

Audio Processing Raw demodulated data from the receiver is processed within the DSP.

The sample rate at this point is 48 kHz with signal bandwidth limited

only by the IF filter ing. Scaling (dependent on the bandwidth of the RF

channel) is then applied to normalise the signal level for the remaining

audio processing. The sample rate is decimated to 8 kHz and bandpass

audio filtering (0.3 to 3 kHz) is applied. De-emphasis is then applied to

cancel out the receive signals pre-emphasised response and improve

signal-to-noise performance. Optional processing such as decryption or

companding is then applied if applicable.

Data and Signalling

Decoders The data and signalling decoders obtain their signals from various points

within the audio processing chain. The point used depends on the

bandwidth of the decoders and whether de-emphasis is required. Several

decoders may be active simultaneously.

Side Tones Side tones are summed in at the end of the audio-processing chain.

These are tones that provide some form of alert or give the user

confidence an action has been performed. The confidence tones may be

generated in receive or transmit mode. The side-tone level is a fixed

proportion (in the order of –10 dB) relative to full scale in the receive

path.

CODEC The combined audio and side-tone signal is converted to analogue form

by a 16-bit DAC with integral anti-alias filtering. This is followed by a

programmable-gain amplifier with a range of 45 dB in 1.5 dB steps. The

amplifier performs volume control and muting. The DAC and volume

control are part of the same CODEC device (AD6521).

TM8100 Mobile Radio Service Manual General Description 57

May 2004 © Tait Electronics Limited

Output to Speakers The output of the CODEC is fed to an audio power amplifier and to the

control head via a buffer amplifier. The output configuration of the

audio power amplifier is balanced and drives an internal speaker and,

optionally, an external speaker. The speaker loads are connected in

parallel rather than being switched. The power delivered to each speaker

is limited by its impedance. The internal speaker has 16 Ω impedance

whereas the external speaker can be as low as 4 Ω.

2.5 Operation in Transmit Mode

Transmit Path This subsection describes the functioning of the radio in transmit mode.

Detailed descriptions of the circuitry involved are given in Section 3

(on page 63). As shown in Figure 2.14, the transmit path exists in the

hardware, custom-logic and DSP domains. From a functional point of

view there are three major parts:

■audio processing and signalling

■frequency synthesizer

■RF transmitter

These functional parts are described in detail below.

Audio Processing and Signalling

Microphone Input The input to the transmitter path begins at the microphone input. There

are two microphone sources: a fist microphone connected to the control

head and an auxiliary microphone connected via the auxiliary or external

options connector. Only electret-type microphones are supported.

Support for optional dynamic fist microphones is facilitated by a

hardware amplifier and filter; this circuitry is mounted on a separate

board that needs to be installed in the control head.

Analogue Processing

of Microphone Signal The CODEC (AD6521) performs microphone selection and

amplification. The microphone amplifier consists of an amplifier with a

fixed gain of 16 dB followed by a programmable-gain amplifier with 0 to

22 dB gain. The amplified microphone signal is converted to a digital

stream by a 16-bit ADC with integral anti-alias filtering (0.1 to 3.2 kHz).

The digital stream is transported to the DSP for further audio processing.

Automatic Level

Control The ALC (automatic level control) follows, and is used to effectively

increase dynamic range by boosting the gain of the microphone pre-

amplifier under quiet conditions and reducing the gain under noisy

acoustic conditions. The ALC function resides in the DSP and controls

the microphone programmable-gain amplifier in the CODEC. The

ALC has a fast-attack (about 10 ms) and slow-decay (up to 2 s)

characteristic. This characteristic ensures that the peak signal level is

regulated near full scale to maximise dynamic range.

58 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

DSP Audio Processing The output of the automatic level control provides the input to the DSP

audio-processing chain at a sample rate of 8 kHz. Optional processing

such as encryption or companding is done first if applicable. Pre-

emphasis, if required, is then applied. The pre-emphasised signal is hard-

limited to prevent over-deviation, and filtered to remove high-frequency

components. The sample rate is then interpolated up to 48 kHz and

scaled to be suitable for the frequency synthesizer.

Data and Signalling

Encoders The data and signalling encoders inject their signals into various points

within the audio-processing chain. The injection point depends on the

bandwidth of the encoders and whether pre-emphasis is required.

Frequency Synthesizer

Main Parts of

Synthesizer As shown in Figure 2.14, the frequency synthesizer consists of two main

parts:

■FCL (frequency control loop)

■RF PLL (phase-locked loop)

The FCL and RF PLL are described briefly below. Detailed descriptions

of the circuitry are given in Section 3 (on page 63). Note that patents

are pending for several aspects of the synthesizer design.

Frequency Control

Loop The FCL consists of the following:

■TCXO

■mixer

■loop filter

■VCXO (voltage-controlled crystal oscillator)

■frequency control block

The FCL provides the reference frequency for the RF PLL. It generates

a high-stability reference frequency that can be both modulated and

offset in fine resolution steps.

RF PLL The RF PLL consists of the following:

■RF PLL device

■loop filter

■VCO (voltage-controlled oscillator)

■VCO output switch

The RF PLL has fast-locking capability but coarse frequency resolution.

The above combination of control loops creates improved frequency

generation and acquisition capabilities.

TM8100 Mobile Radio Service Manual General Description 59

May 2004 © Tait Electronics Limited

Operation of

Control Loop The RF PLL is a conventional integer-N design with frequency

resolution of 25 Hz. In transmit mode the loop locks to the transmit

frequency, whereas in receive mode it locks to the receive frequency

minus the first IF frequency.

Initially, the VCO generates an unregulated frequency in the required

range. This is fed to the PLL device (ADF4111) and divided down by a

programmed ratio to approximately 25 kHz. The reference frequency

input from the FCL is also divided down to approximately 25 kHz. The

phase of the two signals is compared and the error translated into a DC

voltage by a programmable charge pump and dual-bandwidth loop filter.

This DC signal is used to control the VCO frequency and reduce the

initial error. The loop eventually settles to a point that minimises the

phase error between divided-down reference and VCO frequencies.

The net result is that the loop “locks” to a programmed multiple of the

reference frequency.

The FCL generates an output of 13.012 ± 0.004 MHz. Initially a

VCXO produces a quasi-regulated frequency in the required range. The

VCXO output is fed to a mixer where it is mixed with the 13.000 MHz

TCXO frequency. The mixer, after low-pass filtering to remove

unwanted products, produces a nominal frequency of 12 kHz. This is

converted to digital form and transported to the frequency-control block

in custom logic.

The frequency-control block compares the mixer output frequency with

a reference generated by the digital clock, and creates a DC error signal.

A programmed offset is also added. This error signal is converted to

analogue form and used to control the VCXO frequency and reduce the

initial error. Once settled, the loop “locks” to the TCXO frequency

with a programmed offset frequency. The FCL output therefore acquires

the TCXO’s frequency stability.

Modulation The full bandwidth modulation signal is obtained from the DSP in digital

form at a sample rate of 48 kHz. In traditional dual-point modulation

systems the modulation is applied, in analogue form, to both the

frequency reference and the VCO in the RF PLL, combining to produce

a flat modulation response down to DC. Reference modulation is

usually applied directly to the TCXO.

In the system employed in the TM8100 radio, the frequency reference is

generated by the FCL, which itself requires dual-point modulation

injection to allow modulation down to DC. With another modulation

point required in the RF PLL, this system therefore requires triple-point

modulation. The modulation signals applied to the FCL are in digital

form, whereas for the RF PLL (VCO) the modulation signal is applied

in analogue form. The modulation cross-over points occur at

approximately 30 and 300 Hz as determined by the closed loop

bandwidths of the FCL and RF PLL respectively.

60 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Frequency Generation The RF PLL has a frequency resolution of 25 kHz. Higher resolution

cannot be achieved owing to acquisition-time requirements and so for

any given frequency the error could be as high as ±12.5 kHz. This error

is corrected by altering the reference frequency to the RF PLL. The

FCL supplies the reference frequency and is able to adjust it up to

±300 ppm with better than 0.1 ppm resolution (equivalent to better

than 50 Hz resolution at the RF frequency). The FCL offset will usually

be different for receive and transmit modes.

Fast Frequency Settling Both the FCL and RF PLL employ frequency-acquisition speed-up

techniques to achieve fast frequency settling. The frequency-acquisition

process of the FCL and RF PLL is able to occur concurrently with

minimal loop interaction owing to the very large difference in frequency

step size between the loops.

Frequency Acquisition

of RF PLL In the RF PLL the loop bandwidth is initially set high by increasing the

charge pump current and reducing time constants in the loop filter. As

a result settling to within 1 kHz of the final value occurs in under 4 ms.

In order to meet noise performance requirements the loop parameters

are then switched to reduce the loop bandwidth. There is a small

frequency kick as the loop bandwidth is reduced. Total settling time is

under 4.5 ms.

Frequency Acquisition

of FCL The FCL utilises self-calibration techniques that enable it to rapidly settle

close to the final value while the loop is open. The loop is then closed

and settling to the final value occurs with an associated reduction in

noise. The total settling time is typically less than 4 ms.

Calibration The following items are calibrated in the frequency synthesizer:

■nominal frequency

■KVCO

■KVCXO

■VCO deviation

Calibration of the nominal frequency is achieved by adding a fixed offset

to the FCL nominal frequency; the TCXO frequency itself is not

adjusted. The items KVCO and KVCXO are the control sensitivities of

the RF VCO (in MHz/V) and VCXO (in kHz/V) respectively. The

latter has temperature compensation.

TM8100 Mobile Radio Service Manual General Description 61

May 2004 © Tait Electronics Limited

RF transmitter

RF Power Amplifier

and Switching The RF PA (power amplifier) is a four-stage line-up with approximately

42 dB of power gain. The output of the frequency synthesizer is first

buffered to reduce kick during power ramping. The buffer output goes

to a broad-band exciter IC that produces approximately 200 mW output.

This is followed by an LDMOS driver producing up to 2 W output that

is power-controlled. The final stage consists of two parallel LDMOS

devices producing enough power to provide 25 W at the RF connector.

Output of RF

Power Amplifier The output of the RF PA passes through a dual-directional coupler, used

for power control and monitoring, to the PIN switch. The PIN switch

toggles the antenna path between the receiver and transmitter in receive

and transmit modes respectively. Finally, the output is low-pass-filtered

to bring harmonic levels within specification.

Power Control The steady-state power output of the transmitter is regulated using a

hardware control loop. The forward power output from the RF PA is

sensed by the directional coupler and fed back to the power control loop.

The PA output power is controlled by varying driver gate bias voltage

that has a calibrated maximum limit to prevent overdrive. The power

control signal is supplied by a 13-bit DAC driven by custom logic.

Figure 2.15 Typical ramping waveform

Bias

ramp

Power

ramp

Bias

ramp

Power

ramp

Hi power

Lo power

Power

Time

62 General Description TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Ramping Power ramp-up consists of two stages:

■bias

■power ramping

The timing between these two stages is carefully controlled in order to

achieve the correct overall wave shape and meet the specification for

transient ACP (adjacent channel power). A typical ramping waveform is

shown in Figure 2.15.

Bias Ramp-up The steady-state final-stage bias level is supplied by an 8-bit DAC

programmed prior to ramp-up but held to zero by a switch on the DAC

output under the control of a TX INHIBIT signal. Bias ramp-up begins upon

release by the TX INHIBIT signal with the ramping shape being determined

by a low-pass filter. Owing to power leakage through the PA chain,

ramping the bias takes the PA output power from less than –10 dBm to

approximately 25 dB below steady-state power.

Power Ramp-up The power ramp signal is supplied by a 13-bit DAC that is controlled by

custom logic. The ramp is generated using a look-up table in custom

logic memory that is played back at the correct rate to the DAC to

produce the desired waveform. The ramp-up and ramp-down

waveforms are produced by playing back the look-up table in forward

and reverse order respectively. For a given power level the look-up table

values are scaled by a steady-state power constant so that the ramp

waveform shape remains the same for all power levels.

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3 Circuit Descriptions

Scope of Section This section contains descriptions of the circuitry of the control-head

board and each of the modules of the main board. The latter are the

transmitter, receiver, frequency synthesizer and FCL, CODEC and audio

circuitry, power supply, and interface circuitry. Since the digital board is

not serviceable at level-2, no description of the digital circuitry is given.

3.1 Control-head Board

Introduction This subsection describes the circuitry of the control-head boards for the

one- and two-digit-display control heads. The boards differ only in their

layouts; the components are identical. The circuit description given

below is sufficiently general to be applicable to both boards.

Connectors and

UI Devices The control-head board includes the circuitry for the seven keys, 18

LEDs, and the LCD device of the control head. Also mounted on the

board are the volume-control potentiometer and the following five

connectors:

■control-head connector

■microphone connector

■speaker connector

■two connectors for optional circuit board

Protection circuitry is provided for the microphone connector. The

optional circuit board is installed when a dynamic microphone is used or

a concealed microphone is fitted.

Basic Circuitry The LCD driver is based on IC2, IC5 and IC7. Electrical contact

between the control head and the LCD itself is via two elastomeric strips

as described in Subsection 2.1 (on page 33). There are pads on the board

for the seven keys — four function keys, two channel-selection keys, and

an ON/OFF key. The device IC4 reads the status of the function and

channel-selection keys. Of the 18 LEDs, there are red, orange and green

STATUS LEDs, and four green LEDs for the function keys, as well as 11

green LEDs for back-lighting — one for each key and four for the LCD.

The four dual switching transistors Q1 to Q4 control the switching of

the LEDs; the transistors are driven by IC3.

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Serial Peripheral

Interface The control-head board uses an SPI (serial peripheral interface) to

control the display on the LCD, turn back-lighting on and off, control

the STATUS LEDs, and read the status of the keys. The interface consists

of the following four lines at the control-head connector:

■pin 11: data out CH SPI DO

■pin 12: latch line CH LE

■pin 15: data in CH SPI DI

■pin 16: clock CH SPI CLK

The handling of the data is described below.

Data Input and Output Data that are input to the control head are clocked through the LCD

driver and daisy-chained to a shift register. Once all the data have been

clocked in, the latch line is driven low. On this falling edge all the

outputs (LEDs and LCD segments) are driven to their new state. When

the latch line is driven high, the state of each key is latched into another

shift register. The data are then clocked out back to the radio body so

that the radio can respond accordingly.

LCD Driver An oscillator is used to run the LCD. It oscillates at about 60 Hz and

employs a Schmitt trigger and D flip-flop to ensure a 50% duty cycle to

the LCD. A reset circuit is required because the reset from the main

board is not routed to the control head. The reset circuit also employs a

Schmitt trigger.

Volume Control The volume-control potentiometer is linear and passes the DC voltage

signal VOL WIP DC to the radio body. The signal is read by an ADC on the

main board, and the volume is adjusted accordingly.

3.2 Transmitter

Broadband Exciter The transmitter circuitry is given on sheet 3 of the circuit diagram for

the main board. The broadband exciter is a common element in all the

variants of the TM8100 mobile radio, as it operates across all frequencies

from 66 MHz to 940 MHz. It is made up of Q300 and Q303, which

amplify the signal provided by the frequency synthesizer from its level of

7 to 9 dBm up to 24.5 dBm for the frequency band from 66 to 530 MHz

and slightly less than this for the bands covering 530 MHz to 940 MHz.

The exciter operates in full saturation, thereby maintaining a constant

output power independent of the varying input power level supplied by

the synthesizer (7 to 9 dBm).

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Power Amplifier The power amplifier comprises the driver amplifier Q306 and two

paralleled final devices Q309 and Q310. The 24.5 dBm signal from the

broadband exciter is reduced by a band-dependent pi-attenuator and is

amplified by Q306. The resulting signal is then amplified a second time

by Q309 and Q310 to produce a typical output power of 42 W when

measured after the series capacitors at the start of the directional coupler

(C348, C349, C350). The high-level RF signal passes via the directional

coupler, the transmit-receive PIN switch, and the low pass filter, through

to the antenna. The low-pass filter is used to attenuate unwanted

harmonic frequencies.

Power Control Loop Calibration is used to adjust the power control loop, thus setting the

output of the transmitter to one of four preferred power levels (1, 5, 12

and 25 watts). The loop maintains these power settings under changing

environmental conditions. The control mechanism for this loop is via

the DAC IC204 and one of the operational amplifiers making up IC301.

The power control loop will be inhibited if for any reason an out-of-lock

signal is detected from the synthesizer. This ensures that no erroneous

signals are transmitted at any time. The power control loop senses the

forward power by means of the diode D304. This signal is fed to the

buffer and a band-limited operational amplifier back to the gate of Q306.

A voltage clamp (one of the operational amplifiers of IC301) for Q306

limits the maximum current that this device can draw.

Directional Coupler The directional coupler actively senses the forward power and feeds it

back to the power-control circuit. If the directional coupler detects too

much reverse power, indicating a badly matched antenna, the transmitter

will be reduced to the lowest power setting.

Temperature Sensor For added protection, a temperature sensor ensures that the transmitter

power is reduced to very low levels should a temperature threshold be

exceeded. If the temperature does not decrease, the transmitter is

switched off.

3.3 Receiver

Introduction The receiver circuitry is given on sheet 4 of the circuit diagram for the

main board. The receiver is of the triple-conversion superheterodyne

type. The first two IF stages are implemented in hardware; the third stage

is implemented in the FPGA (field-programmable gate array) of the

digital board. The FPGA also carries out the demodulation of the

received signals.

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Front-end Circuitry The front-end circuitry is a standard varicap-tuned singlet (band-pass

filter), followed by an LNA (low-noise amplifier), and then a varicap-

tuned doublet (image filter). The varicap tuning voltage CDC RX FE TUNE

is provided by a DAC, with voltages calculated from a calibration table

stored in non-volatile memory. The two varicap-tuned filters need to be

calibrated to ensure that maximum sensitivity is achieved.

First Mixer The first mixer is a standard diode-ring mixer with SMD (surface-mount

device) baluns and a quadruple SMD diode. For the VHF band the

receiver includes a circuit for suppressing ignition noise. This circuit

momentarily removes the LO signal from the mixer when an ignition

noise pulse is detected. The ignition-noise suppressor is selectable on a

per-channel basis when the radio is programmed.

First IF Stage and

Second Mixer The first IF stage consists of a crystal channel filter (BPF1), followed by

an IF amplifier, and then another crystal filter (BPF2). The second mixer

is an IC quadrature mixer with an internal AGC amplifier. This IC has

a divide-by-two function on the LO input in order to provide the

quadrature LO frequencies required internally. The second LO

frequency is synthesized by an integer PLL (IC403), which uses the

TCXO frequency SYN RX OSC (13.0000 MHz) as its reference.

Frequencies

of IF Stages The frequency of the first IF stage depends as follows on the frequency

band of the radio:

■B1 band: 21.400 029 MHz

■D1 band: 21.400 029 MHz

■H5 band: 45.100 134 MHz

■H6 band: 45.100 134 MHz

The above are nominal values; the actual frequency will differ by a small

amount depending on the exact initial frequency of the TCXO. The

frequency of the second IF stage will always be precisely 64.000 kHz

once the TCXO calibration has been completed. (The TCXO

calibration does not adjust the TCXO frequency, but instead adjusts the

VCXO frequency, which in turn adjusts the VCO or first LO frequency

as well as the frequency of the first IF stage. The second LO frequency

remains fixed.) The third IF stage is completely within the FPGA and is

not accessible.

Demodulation Demodulation takes place within the FPGA. Demodulated audio is

passed to the DSP of the digital board for processing of the receiver audio

signal. Raw demodulated audio can be tapped out from the DSP for use

with an external modem. The modem may be connected to the

auxiliary connector or to the external options connector when an

internal options board is fitted.

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Automatic Gain Control The receiver has an AGC circuit to enable it to cover a large signal range.

Most of the circuit functions are implemented in the FPGA. The FPGA

passes the AGC signal to the CODEC IC204 for output from pin 14

(IDACOUT) and thence via IC201 as the signal CDC RX AGC to pin 23 of the

quadrature mixer IC400. As the antenna signal increases, the AGC

voltage decreases.

Channel Filtering The channel filtering is split between the first and third IF stages. The

channel filtering circuit in the first IF stage comprises a pair of two-pole

crystal filters. The first filter has a 3 dB bandwidth of 12 kHz, and the

second a 3 dB bandwidth of 15 kHz. Most of the channel filtering,

however, is implemented in the FPGA. When the radio is programmed,

the different filters are selected as assigned by the channel programming.

The selectable filters plus the fixed crystal filters result in the following

total IF 3 dB bandwidths:

■wide channel spacing : 12.6 kHz

■medium channel spacing: 12.0 kHz

■narrow channel spacing : 7.8 kHz

(The FPGA runs from the DIG SYS CLK signal, which has a frequency of

12.288 MHz.) The receiver requires the TCXO calibration to be

completed to ensure that the channel filtering is centred, thereby

minimising distortion.

Received Signal

Strength Indication The RSSI is calculated in the FPGA and DSP, and can be passed as an

analogue voltage to the internal options interface and the external

auxiliary interface. To obtain an accurate estimate of the RSSI (over the

signal level and frequency), it is necessary to calibrate the AGC

characteristic of the receiver and the front-end gain versus the receive

frequency.

3.4 Frequency Synthesizer

Introduction The frequency synthesizer includes an active loop filter, one or two

VCOs and buffer amplifiers, and a PLL IC. The last-named uses

conventional integer-N frequency division and includes a built-in charge

pump. Speed-up techniques ensure a transmit-receive settling time of

less than 4.5 ms while retaining low noise characteristics in static

operation. In the following description of the circuitry, first the

necessary power supplies and then the synthesizer itself are discussed. The

circuitry is given on sheet 5 of the circuit diagram for the main board.

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Power Supplies Several power supplies are used by the frequency synthesizer owing to a

combination of performance requirements and the availability of suitable

components. The PLL IC includes analogue and digital circuitry and

uses separate power supplies for each section. The digital section is run

on 3 V, while the analogue section is run on approximately 5 V. The

VCOs and buffer amplifiers run off a supply of about 5.3 V. The active

loop filter requires a supply of 14 to 15 V, and a reference voltage of

approximately 2.5 V.

Performance

Requirements Low noise and good regulation of the power supply are essential to the

performance of the synthesizer. A 6 V regulator IC provides good line

regulation of the 9 V supply and good load regulation. Good regulation

of the power-supply line and load is essential for meeting the transient

ACP requirements. The regulator output voltage is electrically noisy,

however, and filtering is essential. Filtering of the power supply is

achieved with two capacitance multipliers (Q508 and C585 for the VCO

supply, and Q512 and C579 for the PLL and loop-filter supply). The

VCO (or VCOs) use a separate capacitance multiplier because these

multipliers have poor load regulation and the VCOs impart sufficient

load transients to warrant a separate supply.

Effect of Tuning Range For reasons of noise performance, the VCOs are designed to be tuned

within a range of 2 to 12 V. Active tuning circuitr y is required. An active

loop filter incorporating an IC operational amplifier achieves this range

with a suitable power supply voltage. Normal synthesizer switching

behaviour involves overshoot, which dictates that the tuning voltage

range must extend above and below the range of 2 to 12 V. The 14 V

limit is a result of limits on the working supply voltage of the IC

operational amplifier.

Switch-mode Power

Supply The power supply VCL SUPPLY for the active loop filter is provided by a

SMPS (switch-mode power supply), which is in turn powered by 9 V.

The SMPS consists of an oscillator (switching circuit) and a detector.

The output voltage is monitored by a feedback circuit that controls the

DC bias of the switching circuit to maintain a constant output voltage.

Synthesizer Circuitry The essential function of the PLL frequency synthesizer is to multiply a

25 kHz reference frequency to give any desired frequency that is an

integer multiple of 25 kHz. There are some constraints imposed by the

capabilities of the synthesizer hardware, especially the tuning range of the

VCOs.

Reference Frequency The 25 kHz (approximate) reference is obtained by dividing the 13 MHz

(approximate) output of the FCL. Any error in the FCL output

frequency will be multiplied by the synthesizer. Therefore, if the

synthesizer is locked but not the FCL, then the synthesizer output

frequency will be wrong. The FCL frequency division is performed by

a digital counter inside the PLL IC. The divider setting is constant.

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VCO Frequency and

Output Power The output frequency from the synthesizer is generated by a VCO. The

VCO frequency is tuned across the frequency range of the radio by

means of a DC control voltage, typically between 2 V and 12 V. The

VCO output power is amplified by a buffer amplifier. The power is low

and varies from band to band. The buffer output power depends on

which mode — receive or transmit — is used. In receive mode the

output power should be about 7 dBm, whereas in transmit mode it

should be about 9 dBm.

Dual VCOs Some variants of the synthesizer use two VCOs: one for receive and one

for transmit. Synthesizers with two VCOs share the same tuning signal.

Only one VCO is switched on at a time, and so the PLL IC will see only

one output frequency to tune. A portion of the RF output from the

VCOs is fed to the RF input of the PLL IC. The RF signal is divided

by an integer that would give 25 kHz if the output frequency were

correct.

Phase-locked Loop The PLL IC compares the 25 kHz reference and the divided VCO

signal, and the error is used to control the internal charge pump. The

charge pump is a current source that can sink or source current in

proportion to the frequency or phase error. The output is a series of

25 kHz pulses with a width that is dependent on the phase error. When

the output frequency of the synthesizer is correct, there is no error and

the charge pump output will become open circuit.

Active Loop Filter The loop filter continuously integrates the current pulses from the charge

pump and produces a steady DC output voltage that tunes the VCO (or

VCOs). When the VCO frequency is correct, there is no frequency

error and therefore no charge-pump output, and so the loop filter’s

output voltage remains constant. If the frequency is too high or too low,

the error will result in the output of charge-pump current pulses

(negative or positive depending on the sign of the error). The loop filter’s

output voltage will change accordingly, causing the VCO frequency to

change in proportion. The synthesizer design is such that normally the

VCO frequency will be automatically corrected.

Re-tuning of VCO

Frequency When the radio changes channels or switches between receive and

transmit, the VCO frequency must be changed. The rate at which the

VCO is re-tuned is dependent on many factors, of which the loop filter

is the main factor. The loop filter is an integrator built around an

operational amplifier. The resistors and capacitors of the filter affect both

the switching time and the stability of the synthesizer; the values of these

components have been carefully selected to give optimum control

characteristics.

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Speed-up Techniques To reduce the change-over time between transmit and receive, part-time

speed-up techniques have been implemented. Speed-up involves

changing some resistor values while simultaneously changing the PLL IC

settings. This process is implemented in hardware under software control

in conjunction with use of the synthesized reference input. The result is

a transmit-receive settling time of less than 4.5 ms. (The switching time

is measured for a frequency change equal to the first IF plus 10 MHz or

1 MHz, depending on the repeater offsets used for the band. This

implies a synthesizer transmit-receive change-over plus an offset of

1 MHz or 10 MHz in less than 4.5 ms. The ramp-up and ramp-down

of the transmitter, which totals 1 ms, extends this change-over time to

5.5 ms.)

3.5 Frequency Control Loop

Introduction The FCL forms part of the frequency-synthesizer module. The basis of

the FCL is a VCXO, which generates the reference frequency required

by the main PLL of the synthesizer. The FCL circuitry is given on sheet

5 of the circuit diagram for the main board, and is described below.

Elements of

FCL Circuitry The FCL is a simple frequency-locked loop. The circuitry consists of the

following elements:

■VCXO (XL501, Q501, Q503)

■TCXO (XL500)

■buffer amplifier (IC500)

■mixer (IC501)

■low-pass filter (IC502, pins 5 to 7)

■modulator buffer amplifier (IC502, pins 1 to 3)

The TCXO supplies a reference frequency of 13.0000 MHz, which is

extremely stable, regardless of the temperature. The VCXO runs at a

nominal frequency of 13.0000 MHz, and is frequency-locked to the

TCXO reference frequency.

Circuit Operation The VCXO output is mixed with the TCXO output to create a nominal

difference (or offset) frequency SYN CDC FCL of 12.0 kHz. The signal

SYN CDC FCL is fed via the CODEC IC502 in the CODEC circuitry to

the FPGA on the digital board. The FPGA detects the offset frequency,

compares it with the programmed offset frequency, and outputs a

corresponding feedback signal CDC VCXO MOD via IC205. The feedback

signal is amplified and inverted by the modulator buffer amplifier and

output as the loop voltage for the VCXO. With this design the VCXO

frequency can be adjusted by very small precise amounts, and because the

loop is locked, the VCXO inherits the temperature stability of the

TCXO.

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Modulation The FCL modulation is implemented within the FPGA and appears at

the output of IC205, and therefore on the VCXO loop voltage.

Consequently, the VCXO is frequency modulated directly by the

relevant modulation information. The latter may be the microphone

audio, an audio tap-in signal, internal modem signals, or any

combination of these.

3.6 CODEC and Audio Circuitry

CODEC Circuitry The CODEC circuitry and audio circuitry are given on sheet 2 of the

circuit diagram for the main board. Regarding the former, analogue-to-

digital conversion and digital-to-analogue conversion is performed by

the devices IC203, IC204 and IC205.

Device IC203 IC203 is an eight-channel DAC that provides control of transmitter

biasing, front-end tuning, and the output of analogue RSSI signals. The

digital input data are fed to IC203 in synchronous serial form. Three of

the DAC channels are not used.

Device IC205 IC205 contains two CODECs. One is used by the FCL. The second is

used for auxiliary audio (input) and VCO modulation (output). The

digital section communicates with this device via a four-wire

synchronous serial interface.

Device IC204 IC204 contains base-band, voice-band and auxiliary CODECs and some

analogue signal conditioning. The reference voltage (nominally 1.2 V)

for these CODECs is provided internally by IC204 but is decoupled

externally by C228.

Base-band CODEC The base-band CODEC handles the I and Q outputs (IRXP, IRXN, QRXP

and QRXN balls) of the receiver’s second IF stage. The analogue signals are

differential and biased at 1.2 V nominally. The digital section

communicates with this CODEC via a two-wire synchronous serial

interface (BSDO and BSOFS balls). The digital-to-analogue conversion

section of the base-band CODEC is not used.

Voice-band CODEC The voice-band CODEC handles the microphone and speaker signals.

The digital section communicates with this CODEC via a three-wire

synchronous serial interface (VSFS, VSDO and VSDI balls). IC204 also

contains voice-band filtering, pre-amplification and volume control.

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Auxiliary CODEC The auxiliary CODEC handles transmitter power control, receiver gain

control, auxiliary audio output and general analogue monitoring

functions. The digital section communicates with this CODEC via a

three-wire synchronous serial interface (ASFS, ASDI and ASDO balls). The

DAC used for receiver gain control (IDACOUT ball) is a current output type.

Current-to-voltage conversion is performed by R238. The full-scale

output of 1.2 V is amplified by IC201 to approximately 3 V as required

by the receiver.

Audio Circuitry The audio circuitry performs four functions:

■output of audio signal for speaker

■input of microphone audio signal

■input of auxiliary audio signal

■output of auxiliary audio signal

The sections of the circuitry concerned with these functions are

described below.

Audio Signal

for Speaker The audio signal for the speaker is generated by IC204 (VOUTAUXP ball).

This signal is post-volume-control and has a pre-emphasised frequency

response. The signal is then processed by R218, R217 and C205 to

restore a flat frequency response and reduce the signal level to that

required by the audio power amplifier.

Summing Circuit The top of C205 is where side tones are summed in and the CDC RX AUD

signal is obtained. C201 and R211 pre-emphasize and attenuate the

side-tone signal to give a flat side-tone frequency response and reduce the

input to an appropriate level.

Buffer Amplifier IC201 (pins 8 to 10) amplifies the signal at the top of C205 by 19 dB and

drives the CDC RX AUD system interface line via C212 and R225. The

capacitor C212 provides AC output coupling and R225 ensures stability.

The DC bias for this amplifier is derived from IC204.

Audio Power Amplifier The signal at the top of C205 is fed via C204 to the audio power

amplifier IC202. IC202 has 46 dB of gain and a differential output

configuration. C209, C211, R252 and R253 ensure stability of the

amplifier at high frequencies. When operational, the output bias voltage

for IC202 is approximately half the radio supply voltage. When not

operational, the output becomes high impedance.

Control of Audio

Power Amplifier Power up, power down, and muting of IC202 is controlled by two signals

from the digital section, DIG AUD PA EN1 and DIG AUD PA EN2. The network

consisting of Q200, Q201, R200 to R206, R210 and R250 converts the

two digital signals to the single three-level analogue signal required by

IC202.

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Microphone Signals There are two microphone source signals:

■ITF AUX MIC AUD from auxiliary or internal options connector

■ITF CH MIC AUD from control head

The biasing for electret microphones is provided by a filtered 3.0 V

supply via R226 and R227. The components R209 and C202 provide

the supply filtering. The microphone inputs to IC204 (VINAUXP, VINAUXN,

VINNORP and VINNORN balls) are differential. The negative inputs are

decoupled to the filtered 3.0 V supply by C215 and C216. The positive

inputs are biased to approximately 1.5 V by R229, R232, R230 and

R233. AC coupling and DC input protection is provided by C213 and

C214.

Auxiliary Audio Input The auxiliary audio input signal ITF AUD TAP IN is DC-coupled to the ADC

input of IC205. R241 combined with internal clamping diodes in

IC205 provide DC protection for the ADC input. IC205 provides the

input biasing of approximately 1.5 V.

Auxiliary Audio Output The source for the auxiliary audio output signal CDC AUD TAP OUT is

provided by IC204 (RAMPDAC ball). The DAC output of IC204 is low-

pass filtered to remove high-frequency artefacts. The low-pass filter,

formed by IC201 (pins 1 to 3), R219, R220, R221, R224, C206, C208

and C210, is a third-order Butterworth type with a cut frequency of

approximately 12 kHz. The output of the low-pass filter is amplified by

6 dB by a buffer amplifier, IC201 (pins 5 to 7), and fed via R207 and

R208 to drive the CDC AUD TAP OUT interface line. The DC bias for this

signal path is provided by IC204 and is approximately 1.2 V when

operational. The offset at CDC AUD TAP OUT is approximately 2.4 V owing

to the gain of the buffer amplifier.

3.7 Power Supply

Introduction The power-supply circuitry consists of the following main sections:

■supply protection

■supervisory circuit

■internal power supplies

■control of internal power supplies

The power-supply circuitry is given on sheet 6 of the circuit diagram for

the main board, and is described below.

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Supply Protection Electrical protection to the radio is provided by the clamping diode

D600 and 10 A fuses in the positive and negative leads of the power

cable. This provides protection from reverse voltages, positive transients

greater than 30 V, and all negative transients. An ADC monitors the

supply and is responsible for the protection of internal devices, which

have an operating voltage of less than 30 V. The ADC also ensures

protection if the radio operates outside its specified voltage range of

10.6 V to 16 V.

Supervisory Circuit The supervisory circuit comprises a reset and watchdog timer. The

circuit provides the reset signal PSU SYS RST to the digital section, which

in turn provides the watchdog signal DIG WD KICK required by the

supervisory circuit.

Internal Power

Supplies There are nine internal power supplies:

■one SMPS

■five linear regulators (+9V0, +6V0, +3V3, +3V0 AN, +2V5 CDC)

■three switched supplies (+9V0 TX, +3V0 RX, +13V8 SW)

The SMPS is used to regulate to 3.3 V from the external supply

+13V8BATT. The four lower voltages required are then further stepped

down with linear regulators. These all take advantage of the efficiency

gain of the SMPS. The 9 V regulator and the 13.8 V switched supply

are connected to +13V8 BATT. The two remaining switched supplies (9 V

and 3 V) use P-channel MOSFETs.

Control of Internal

Power Supplies The radio can be turned on using the ON/OFF key on the control head or

by means of external signals. For the latter case hardware links are

required and there are several power-sense options; these are discussed

below. Some internal power supplies can be controlled by means of

digital lines depending on the mode in which the radio is operating.

Power-sense Options There are five power-sense options for powering up and powering down

the radio:

■battery power sense

■auxiliary power sense

■internal-options power sense

■no power sense

■emergency power sense

The emergency power-sense option can be used in conjunction with any

of the other four options. The ON/OFF key can be used with any of the

options, although the behaviour of the radio will depend on the option

selected. The links LK1 to LK4 on the main board are used to

implement the desired option. The power-sense options and the link

settings are described below.

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Battery Power Sense For the battery-power-sense option the link LK1 is required to connect

+13V8BATT of the power connector to the power-up circuitry. With this

option, when a 13.8 V supply is connected to the radio, the radio enters

the programmed power-on mode. The ON/OFF key can then be used to

turn the radio on and off. This option has the disadvantage that the radio

still draws about 28 mA after being switched off using the ON/OFF key.

The reason is that the radio enters the stand-by mode and does not shut

down completely.

Auxiliary Power Sense With the auxiliary power-sense option the digital input line AUX GPI3 of

the auxiliary connector is used to power up and power down the radio.

The link LK2 is required to connect the line to the power-up circuitry.

The line is active high; it is on when the level exceeds 2.6 V and off

when the level falls below 0.7 V; the line tolerates maximum inputs equal

to the radio supply voltage. When the line becomes active, the radio

enters the programmed power-on mode. The ON/OFF key can then be

used to switch the radio on and off. With the radio off and the line

active, the radio draws about 28 mA. When the line becomes inactive,

the radio is shut down completely regardless of whether it was on or in

stand-by mode. With the line inactive the radio draws less than 1 mA.

In a vehicle installation this avoids flattening the battery when the

ignition key is off.

Internal-options

Power Sense The internal-options power-sense option is similar to the auxiliary

power-sense option, except that the IOP GPIO7 line of the internal options

connector is used. The link LK4 is required to connect the line to the

power-up circuitry. This line is also active high; it is on when the level

exceeds 2.6 V and off when the level falls below 0.7 V; the line tolerates

maximum inputs of 5 V. The behaviour of the ON/OFF key is the same as

with the auxiliary power-sense option.

No Power Sense If no power-sense option is selected, the radio can only be powered up

and powered down by means of the ON/OFF key. For this option the links

LK1, LK2 and LK4 must be removed. The advantage of this option over

the battery power-sense option is that the radio draws less than 1 mA

when it is switched off.

Emergency

Power Sense For the emergency power-sense option the AUX GPI2 line of the auxiliary

connector is used. Externally, this line is typically connected to a hidden

switch. Internally, the link LK3 is required to connect the line to the

power-up circuitry. The line is active low and has an internal pull-up

resistor to the external supply voltage. The line is on when the level falls

below 0.7 V. When the line becomes active, as when the hidden switch

is pressed for two seconds, the radio enters the emergency mode. This

mode can also be activated by making an emergency call or by pressing

a key that has been programmed appropriately. The concealed

microphone is typically fitted when the emergency power-sense option

is selected.

76 Circuit Descriptions TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Operation in

Emergency Mode If the radio is off when the emergency mode is activated, the radio is

powered up but the display on the control head is not switched on. If

the radio is on when the mode is activated, the display is frozen. In the

latter case, if the ON/OFF key is pressed, the display is switched off but the

radio remains in the emergency mode. While in this mode the radio

cycles between transmit and receive. To exit the emergency mode the

ON/OFF key needs to be pressed again.

3.8 Interface Circuitry

Bi-directional Lines Bi-directional lines are provided on four pins of the auxiliary connector,

(AUX GPIO4 to AUX GPIO7) one on the control-head connector (CH GPIO1),

and seven on the internal options connector (IOP GPIO1 to IOP GPIO7).

Those on the auxiliary and control-head connectors are formed by

combining two uni-directional lines. For example, the line AUX GPIO4 at

pin 10 of the auxiliary connector is formed from ITF AUX GPI4 and DIG AUX

GPO4. The circuitry is the same in all five cases and is explained below

for the case of AUX GPIO4.

Output Signals An output on the line AUX GPIO4 originates as the 3.3 V signal

DIG AUX GPO4 from the digital section. The signal is first inverted by Q703

(pins 3 to 5) and the output divided down to 1.6 V by R746 and R753

to drive the base of Q703 (pins 1, 2 and 6). When the latter’s collector

current is low, the base current is a maximum and creates a small voltage

drop across R761, causing the collector emitter to saturate. As the

collector current increases, the base current decreases proportionally

until the voltage across R761 reaches 1 V. At this point the base-emitter

begins to turn off and the base current diminishes rapidly. The net effect

is a current-limiting action. The current limit value is approximately

18 mA (the inverse of the value of R761). The output configuration is

open-collector with a pull-up to 3.3 V by default. Pull-up options to

5 V and 13.8 V are also available.

Five-volt Regulator The 5 V supply mentioned above is provided by a simple buffered zener

regulator formed by Q702, D721, R721 and R722. The resistor R722

limits the current to about 25 mA under short-circuit conditions.

Input Signals

(AUX GPIO4)An input signal applied to AUX GPIO4 is coupled via R757 to ITF AUX GPI4

and fed to the digital section. As the input signal may exceed the

maximum allowed by the digital section, it is clamped by D711 and a

shunt regulator. The shunt regulator consists of Q708, R719 and R720

and begins to turn on at approximately 2.7 V. In combination with

D711, the input to ITF AUX GPI4 is therefore clamped to 3.3 V nominally.

The value of R757 is made large to minimise the loading effect on the

output pull-up resistors. On AUX GPIO4 only, the optional MOSFET

Q707, which has a high current drive, may be fitted.

TM8100 Mobile Radio Service Manual Circuit Descriptions 77

May 2004 © Tait Electronics Limited

Input Signals

(AUX GPI1 to AUX GPI3)Dedicated inputs are provided on three pins of the auxiliary connector

(AUX GPI1 to AUX GPI3). AUX GPI1 is a general-purpose input with strong

protection of the same type used for AUX GPIO4. AUX GPI2 is normally a

dedicated emergency input but can be made a general-purpose input like

AUX GPI1 by removing the link LK3 in the power supply area. AUX GPI3 is

normally a dedicated ignition-sense input but can be made a general-

purpose input like AUX GPI1 by removing the link LK2 in the power

supply area and fitting the 33 kΩ resistor R775.

ESD Protection On exposed inputs of the auxiliary and control-head connectors ESD

(electrostatic discharge) protection is provided by a 470 pF capacitor and

by clamping diodes to ground and to 13.8 V. For example, on AUX GPIO4

this would consist of D713 and C725. The lines IOP GPIO1 to IOP GPIO7

are intended for connection to internal digital devices and so these have

relatively light protection.

Hookswitch Detection Hookswitch detection is performed by Q700, R709, R706 and R712.

When the resistance to ground on the PTT line is less than 13.2 kΩ,

Q700 will turn on and drive the ITF CH HOOK line high; this indicates

either that the microphone is on hook or that the PTT (press-to-talk)

switch is pressed.

78 Circuit Descriptions TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

TM8100 Mobile Radio Service Manual Servicing of Radio 79

May 2004 © Tait Electronics Limited

TM8000 mobiles

Chapter 2

Servicing of Radio

80 Servicing of Radio TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Chapter 2 Contents

4 General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4.1 Repair Levels and Website Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

4.2 Tools, Equipment and Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4.3 Servicing Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.4 SMT Repair Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.5 Equipment Set-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

5 Servicing Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107

5.1 Initial Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

5.2 Fault Diagnosis and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.3 Final Inspection, Test and Administration . . . . . . . . . . . . . . . . . . . . . . . . 121

6 Disassembly and Re-assembly of Radio . . . . . . . . . . . . . . . . . . . . . . .125

6.1 Detachment of Control Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

6.2 Disassembly of Control Head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

6.3 Disassembly of Radio Body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

6.4 Re-assembly of Radio Body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

6.5 Re-assembly and Attachment of Control Head. . . . . . . . . . . . . . . . . . . . 148

7 Servicing of Control Head . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151

7.1 Faults not Involving Control-head Board . . . . . . . . . . . . . . . . . . . . . . . . 151

7.2 Faults Involving Control-head Board . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

7.3 Replacement of Faulty Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

7.4 Replacement of Faulty Control-head Board . . . . . . . . . . . . . . . . . . . . . 163

8 Servicing of Main Board. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165

8.1 Fault Diagnosis and Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

8.2 Replacement of Faulty Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

8.3 Replacement of Faulty Main-board Assembly. . . . . . . . . . . . . . . . . . . . . 169

9 Diagnosis of Faults on Main Board. . . . . . . . . . . . . . . . . . . . . . . . . . .171

9.1 Power-supply Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

9.2 Interface Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

9.3 Frequency Synthesizer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

9.4 Frequency Control Loop. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191

9.5 Receiver. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197

9.6 Transmitter. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 208

9.7 CODEC and Audio Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236

TM8100 Mobile Radio Service Manual General Information 81

May 2004 © Tait Electronics Limited

4 General Information

Scope of Section This section discusses the two repair levels covered by the service manual,

details concerning website access, the tools, equipment and spares

required, and the setting up of the necessary test equipment. General

servicing precautions are also given, as well as details of certain non-

standard SMT techniques required for level-2 repairs.

4.1 Repair Levels and Website Access

Repair Levels As described in Section 1, this manual covers level-1 and level-2 repairs

of TM8100 radios. To summarise, level-1 repairs comprise the

replacement of control-head boards, main-board assemblies, and other

parts of the radio; level-2 repairs comprise repairs of control-head boards

and, except for special items, main-board assemblies. The special items

are:

■digital board

■RF PAs (Q309 and Q310)

■CODEC 1 (IC204)

■copper plate

Replacements of the connectors and volume-control potentiometer on

the control-head board are level-1 repairs. Replacements of the

connectors on the main-board assembly, however, are level-2 repairs

because these repairs entail the disassembly of the main-board assembly.

Important The circuit boards in the TM8100 radio are complex.

They should be serviced only by accredited service

centres. Repairs attempted without the necessary

equipment and tools or by untrained personnel might

result in permanent damage to the radio.

Accreditation of

Service Centres Service centres that wish to achieve ASC status should contact Technical

Support. They will need to provide evidence that they meet the criteria

required for accreditation; Technical Support will supply details of these

criteria. These centres must then make available suitable staff for training

by TEL personnel, allow their service facilities to be assessed, and provide

adequate documentation of their processes. They will be accorded ASC

status and endorsed for repairs of TM8100 radios after their staff have

been trained and their facilities confirmed as suitable. Existing ASCs

need to apply for and be granted an endorsement for repairs of TM8100

radios. All ASCs with the necessary endorsements may carry out level-

1 and level-2 repairs of these radios, whether under warranty or not.

82 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Skills and Resources

for Level-1 Repairs For level-1 repairs basic electronic repair skills are sufficient. Apart from

the standard tools and equipment of any service centre, certain torque

drivers are required as well as a service kit and, for diagnostic purposes,

a spare control head. Replacement control-head boards and main-board

assemblies are supplied by TEL in separate spares kits. The other

replacement parts are supplied in four spares kits: parts for the one-digit-

display control head, parts for the two-digit-display control head, parts

for the radio body, and spare control-head seals. Further details are given

in Subsection 4.2 (on page 84).

Skills and Resources

for Level-2 Repairs For level-2 repairs expertise is required in SMT repairs of circuit boards

with a very high complexity and extreme component density. Apart

from the tools and equipment needed for level-1 repairs, the standard

SMT repair tools are required. A can-removal tool is strongly

recommended but not mandatory. Replacement SMT components are

supplied by TEL in two separate spares kits, one for the control-head

boards and one for the main board. Spare special items are not supplied.

Further details are given in Subsection 4.2.

Website Access To carry out level-1 and level-2 repairs, service centres need access to the

secured portion of the Technical Support website. There are different

access levels; those required for level-1 and level-2 repairs are:

■level-1 repairs: associate access

■level-2 repairs: Tait-only access

Log-in passwords are needed for associate and Tait-only access; Technical

Support supplies service centres with the necessary log-in information.

(The unsecured portion of the Technical Support website is accessible to

the general public. This type of access is called public access, and no log-

in password is required.)

Items Available

on Website The information available at the different access levels is summarised in

Table 4.1. The technical notes mentioned are of different types.

Associate technical notes relate to the repair of the radio but not the

downloading of firmware; Tait-only technical notes relate to the

firmware. The PCB information packs are discussed in more detail

below.

TM8100 Mobile Radio Service Manual General Information 83

May 2004 © Tait Electronics Limited

PCB Information Packs A PCB information pack for a particular circuit board consists of the

relevant BOMs, grid reference indexes, PCB layouts, and circuit

diagrams. (The grid reference indexes give the locations of components

on the PCB layouts and circuit diagrams.) A PCB information pack is

compiled whenever there is a major change in the layout of the board.

All PCB information packs are published on the Technical Support

website. In the service documentation, however, the PCB information

pack for only the current release of the board is included.

Tait FOCUS Database An additional source of information to service centres is the Tait FOCUS

call-logging database. (This is accessible on the Technical Support

website also.) All Customer-related technical issues regarding the radios

are recorded on this database. These issues may be raised by both

Customers and service centres. Technical Support resolves the issues and

informs the Customer or service centre concerned of the outcome. All

issues and their solutions are available for review by all service centres.

Table 4.1 Items relating to TM8100 radios that are available on the Technical Support website

Item Public access Associate access Tait-only access

Operator’s manuals

User’s guides

Installation guides

Public technical notes

•

Product release notes

Specifications

Calibration software

Programming software

Programming user manuals

Fitting instructions

Service manuals

Associate technical notes

•

Software release information

Firmware

Tait-only technical notes

PCB information packs

•

84 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

4.2 Tools, Equipment and Spares

Torque-dr iv er s For level-1 and level-2 repairs, excluding SMT repairs of the circuit

boards, the torque-drivers listed in Table 4.2 are required. These are the

only special tools required over and above the standard workshop tools.

For level-1 repairs only the Torx T10 and Torx T20 driver bits are

necessary. The sockets are needed for disassembling and re-assembling

the main-board assembly, which is a level-2 task.

Tools for SMT Repairs In general only the standard tools for SMT work are required for level-2

repairs of the circuit boards. In addition, a can-removal tool is

recommended but if none is available, a hot-air tool may be used instead.

However, it should be borne in mind that a hot-air tool affords little

control. Even in skilled hands, use of a hot-air tool to remove cans will

result in rapid uncontrolled rises in the temperature of components

under the can being removed as well as under any adjacent cans. The

circuit board might suffer damage as a result.

Table 4.2 Torque-drivers

Drive type Torque (N.m) Torque (lbf.in) Repair level

Torx T20 2.5 22 1

Torx T10 1.9 17 1

1.7 15 2

0.56 5 1

0.34 3 1

3/16-inch socket 0.90 8 2

14 mm long-reach socket 1.7 15 2

TM8100 Mobile Radio Service Manual General Information 85

May 2004 © Tait Electronics Limited

Test Equipment The following test equipment is required for servicing the radio:

■test PC (with programming and calibration applications loaded)

■RF communications test set (audio bandwidth of at least 10 kHz)

■oscilloscope

■digital current meter (capable of measuring up to 3 A)

■multimeter

■DC power supply (capable of 13.8 V and 10 A)

■spare TM8115 control head

■spare TM8110 control head

■TMAA21-00 service kit

Separate instruments may be used in place of the RF communications

test set. These are an RF signal generator, audio signal generator, audio

analyzer, RF power meter, and modulation meter. Details of the service

kit are given below.

Service Kit The TMAA21-00 service kit contains all the items needed for

connecting the radio to the test equipment. The setting up of the

equipment is described in Subsection 4.5 (on page 93). The service kit

also includes a product support CD and a folder with the necessary

service documentation, including this manual. The CD contains the

programming application, calibration application, and soft-copies of the

service and related documentation. The contents of the service kit are

listed in Table 4.3. Note that the TMAA20-04 cable listed is required

only if the test PC is to be connected directly to the radio for

programming purposes.

Table 4.3 Contents of TMAA21-00 service kit

Product code Item

TMAA21-01 Cable (DB14 socket to RJ45 plug plus in-line connector)

TMAA20-01 Product support CD

TMAA20-02 Adaptor (RJ45 socket to DB9 socket)

TMAA20-03 Cable (power connector to banana plugs plus in-line connector)

TMAA20-04 Cable (RJ12 socket to RJ45 plug)

T2000-A19 Cable (DB9 socket to RJ12 plug)

TOPA-SV-024 Test unit

MM8100-01-00-812 Service and accessories manuals

86 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Spares Kits The spares kits required for the servicing of the radio are listed in

Table 4.4. The corresponding repair levels are also indicated. A spares

kit (Spares kit 6) for the repair of the rugged microphone is also supplied

but is not discussed in this manual; refer to the accessories manual for the

details. The contents of Spares kits 1, 2 and 10 are given in Section 6

(on page 125). Contents lists for Spares kits 4 and 5 are supplied with

the kits.

Table 4.4 Spares kits

Kit number Product code Description Repair level

1 TMAA22-01 Parts of two-digit-display control head

— excluding control-head board

2 TMAA22-02 Mechanical parts of radio body 1

3 TMAA22-03 Control-head boards (two-digit display) 1

4 TMAA22-04 Selected components of control-head boards 2

5 TMAA22-05 Selected components of main board 2

7 TMAA22-07 Control-head seals 1

10 TMAA22-90 Parts of one-digit-display control head

— excluding control-head board

11 TMAA22-91 Control-head boards (one-digit display) 1

TMAA22-12B1 Main-board assembly (B1 band) 1

TMAA22-12H5 Main-board assembly (H5 band) 1

TMAA22-12H6 Main-board assembly (H6 band) 1

TM8100 Mobile Radio Service Manual General Information 87

May 2004 © Tait Electronics Limited

4.3 Servicing Precautions

Introduction This subsection discusses the precautions that need to be taken when

servicing the radios. These precautions fall into the following categories:

■mechanical issues

■compliance issues

■anti-static precautions

■transmitter issues

Service technicians should familiarise themselves with these precautions

before attempting repairs of the radios.

Use of Torque-drivers Apply the correct torque when using a torque-driver to tighten a screw

or nut in the radio. Under-torquing can cause problems with

microphonics and heat transfer. Over-torquing can damage the radio.

Table 6.3 in Section 6 (on page 125) lists the correct torque values for

the different screws and nuts.

Non-scratch Bench Tops Use workbenches with non-scratch bench tops so that the mechanical

parts of the radio are not damaged during disassembly and re-assembly.

(The workbench must also satisfy the anti-static requirements specified

below.) In addition, use a clear area of the bench when disassembling and

re-assembling the radio.

Note The radio is designed to satisfy the applicable compliance

regulations. Do not make modifications or changes to the

radio not expressly approved by TEL. Failure to do so could

invalidate compliance requirements and void the Customer’s

authority to operate the radio.

Sealing of Radio To maintain the sealing of the radio to IP54 standards, ensure that all

bungs and seals are fitted after servicing the radio. These are for the

auxiliary, RF, external options, and programming connectors:

■bung for auxiliary connector

■rubber seal for RF connector

■bung for aperture for options connector (connector not fitted)

■cover seal for options connector (connector fitted)

■cover seal for programming connector (blank control head only)

In addition, ensure that the grommet sealing the aperture to the

microphone connector of two-digit-display control heads is properly

fitted.

88 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Important The components of the circuit boards in the radios are

susceptible to damage from electrostatic discharges.

Observe anti-static precautions when handling the

boards or their components. Follow the procedures

given in the manufacturers’ data books.

Storage and Transport

of Items Always observe anti-static precautions when storing, shipping or

carrying the circuit boards and their components. Use anti-static bags

for circuit boards and anti-static bags or tubes for components that are to

be stored or shipped. Use anti-static bags or trays for carrying circuit

boards, and foil or anti-static bags, trays, or tubes for carrying

components.

Anti-static

Workbenches Use an anti-static workbench installed and tested according to the

manufacturer’s instructions. A typical installation is shown in Figure 4.1.

These benches have a dissipative rubber bench top, a conductive wrist

strap, and a connection to the building earth. The material of the bench

top must satisfy not only anti-static requirements but also the non-scratch

requirements mentioned above.

Figure 4.1 Typical installation of an anti-static workbench

TO BUILDING

EARTH

METAL FRAME

DISSIPATIVE RUBBER

BENCH MAT

CONDUCTIVE WRIST STRAP

TM8100 Mobile Radio Service Manual General Information 89

May 2004 © Tait Electronics Limited

Transmitter Issues The following issues relate to the operation of the transmitter:

■RF and thermal burns

■antenna loading

■test transmissions

■accidental transmissions

■distress beacons

The precautions required in each case are given below.

Caution Avoid thermal burns. Do not touch the cooling

fins or underside of the radio body when the

transmitter is or has been operating. Avoid RF

burns. Do not touch the antenna while the trans-

mitter is operating.

Important The radio has been designed to operate with a 50 Ω

termination impedance, but will tolerate a wide range of

antenna loading conditions. Nevertheless, do not

operate the transmitter without a suitable load. Failure

to do so might result in damage to the power output

stage of the transmitter.

Important While servicing the main board, avoid overheating the

radio during test transmissions. The following is good

practice: Secure the main-board assembly in the chassis

with the two external screws and one of the internal

screws. The screws are labelled 9 and 11 in Figure 2.11.

The heat-transfer block must be secured to the main

board. The lid of the radio body may be left off. After

completing any measurement or test requiring

activation of the transmitter, immediately return the

radio to the receive mode.

Important Under certain circumstances the microprocessor can key

on the transmitter. Ensure that all instruments are

protected at all times from such accidental transmissions.

Note The frequency ranges 156.8 MHz ± 375 kHz,

243 MHz ± 5 kHz, and 406.0 to 406.1 MHz are reserved

worldwide for use by distress beacons. Do not program

transmitters to operate in any of these frequency bands.

90 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 4.2 Locations of the capacitors C548 and C565 and the inductors L601 and L602 on the main

board

VHF BOARD

(UHF BOARD SIMILAR)

UHF BOARD

(VHF BOARD SIMILAR)

TM8100 Mobile Radio Service Manual General Information 91

May 2004 © Tait Electronics Limited

4.4 SMT Repair Techniques

Standard Procedures Service centres carrying out level-2 repairs are expected to be familiar

with the standard techniques for the replacement of SMT components.

However, certain components on the main board require non-standard

techniques and these are discussed below. Another issue of concern is

the procedure for removing and installing cans. A discussion of the issue

concludes this subsection.

Non-standard

Procedures Do not use the standard SMT repair techniques when replacing the

capacitors C548 and C565 and the inductors L601 and L602. The

standard techniques tend to produce excessive heat, which will damage

these components. Do not use a hot-air tool or heat gun. Instead use

solder paste and a standard soldering iron with a number-6 iron tip. The

capacitors are part of the frequency-synthesizer circuitry under the

SYN TOP can. The inductors are part of the SMPS of the power-supply

circuitry on the bottom-side of the board. Figure 4.2 shows the

locations of the components.

Can Removal

and Installation Cans are best removed and installed using a can-removal tool. If this tool

is available, technicians should refer to the documentation supplied with

the tool for the correct procedures. If the tool is not available, a hot-air

tool may be used instead. However, technicians require training in the

best techniques to employ in the absence of a can-removal tool. Such

training is part of the accreditation process for service centres.

Spare Cans It is good practice to discard any can that has been removed and replace

it with a spare can from Spares kit 5. If this is not done, special

precautions are needed when re-installing the original can. These

precautions are discussed as part of the training for accreditation.

92 General Information TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 4.3 Test equipment for servicing radios

RADIO BODY

BLANK

CONTROL HEAD

POWER CONNECTOR

TEST PC

SERIAL PORT

DB9 SOCKET

RJ12 PLUG

COMPUTER

CONNECTOR

RADIO CONNECTOR

DB15 SOCKET

RJ45 PLUG

MICROPHONE

CONNECTOR

IN-LINE

CONNECTOR

AUXILIARY CONNECTOR

BANANA

PLUGS

BNC PLUGTEST UNIT

OSCILLOSCOPE

RX AUDIO/SINAD

CONNECTOR

AUDIO IN HI

RF COMMUNI-

CATIONS

TEST SET

AUDIO OUT

TX AUDIO

CONNECTOR

RADIO BODY

CONTROL HEAD

RF CONNECTOR

BNC PLUG

AUDIO MONITOR

OUTPUT

RF IN/OUT

N-TYPE

CONNECTOR

DC POWER SUPPLY

PROGRAMMING

CONNECTOR

RJ45

PLUG

DB9

SOCKET

ADAPTOR

(SEE INSET FOR CONNECTION

TO BLANK CONTROL HEAD)

AC INPUT

TM8100 Mobile Radio Service Manual General Information 93

May 2004 © Tait Electronics Limited

4.5 Equipment Set-up

Introduction This subsection covers the setting up of the test equipment for servicing

the radios, as well as related aspects:

■setting up of test equipment, including test unit

■use of test unit

■installing programming and calibration applications

■basic programming and calibration tasks

■invoking CCTM (computer-controlled test mode)

■summary tables of CCTM commands and error codes

■visual and aural indications provided by radio

The last-named aspect applies to control heads with UI, and concerns

the STATUS LEDs and LCD screen, and the various alerts and confidence

tones emitted from the speaker.

Connect Equipment Connect the test equipment to the radio as shown in Figure 4.3. Use the

test unit, cables and adaptor of the service kit. Refer to Subsection 4.2

(on page 84) for details of the test equipment and service kit. The face

of the test unit is fitted with a speaker, five switches, and the following

connectors:

■“RADIO” connector (DB15 plug)

■“COMPUTER” connector (RJ12 socket)

■“TX AUDIO” connector (BNC socket)

■“RX AUDIO/SINAD” connector (BNC socket)

These connectors are all required for connecting the test equipment and

radio. Figure 4.4 illustrates the face of the test unit.

Use of Test Unit The test unit facilitates the testing of the receive and transmit functions

of radios. When the switches are set for the required mode, the test unit

automatically routes all signals to the appropriate destinations. The unit

may be used with both mobile and portable radios. A full description is

given in the accessories manual. As shown in Figure 4.4, the switches

are:

■SELECTOR switch

■HOOK switch

■MODE switch

■AUDIO IN switch

■AUDIO OUT switch

For servicing TM8100 radios set the SELECTOR switch to “TM8100”. For

testing receive and transmit functions respectively, the remaining switches

must be set as described below. (When programming or calibrating

radios the switches have no effect, although it is good practice to set the

MODE switch to “RX”.)

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Figure 4.4 Illustration of the face of the test unit

Radio

Tx / PTT

Speaker

Radio

Load

TOP Mod Audio

Mic Audio Rx Audio /

SINAD

Tx Audio

Computer

TOP

Off

Hook On

Hook Off

TM8000 only

TM8000

AUDIO OUT

SWITCH

AUDIO IN

SWITCH

SPEAKER

SELECTOR

SWITCH

HOOK

SWITCH

MODE

SWITCH

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Settings for

Receive Tests For receive tests set the switches on the test unit as follows:

■HOOK switch : “HOOK OFF”

■MODE switch : “RX”

■AUDIO IN switch : “OFF”

■AUDIO OUT switch: “SPEAKER” or “LOAD”

In the last-named case, with the switch in the “SPEAKER” position, the

received audio is output from the test unit’s speaker. In the “LOAD”

position a 16 Ω load is switched into the circuit in place of the test unit’s

speaker. Note, however, that the AUDIO OUT switch has no effect on the

radio’s speaker.

Settings for

Transmit Tests For transmit tests set the switches on the test unit as follows:

■HOOK switch : “HOOK OFF”

■MODE switch : “RX” initially

■AUDIO IN switch : “MIC AUDIO”

■AUDIO OUT switch: (immaterial)

When ready to transmit, set the MODE switch to the “TX/PTT” position.

This switch functions in the same way as the PTT switch on the

microphone.

Product Support CD After setting up the test equipment for the first time, install the

programming and calibration applications on the test PC. These

applications are included on the product support CD supplied with the

service kit. Access the contents of the CD as follows:

1. Insert the product support CD in the CD-ROM drive of the test

PC.

2. The Contents window of the CD should appear; the window is

illustrated in Figure 4.5. If the Contents window fails to appear,

proceed as follows:

3. Click “Start” > “Run”. The “Run” dialogue box appears.

4. Type d:\menu.exe, where d is the letter designating the CD-ROM

drive.

5. Click the “OK” button. The “Run” dialogue box is closed and the

Contents window appears.

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Install Applications The upper two buttons in the Contents window of the product support

CD allow for the installation of the programming and calibration

applications:

1. Click the “Programming” button. Installation of the programming

application begins automatically. Follow the instructions on the

screen to complete the installation.

2. Click the “Calibration” button. Installation of the calibration

application begins automatically. Follow the instructions on the

screen to complete the installation.

3. The Contents window remains open following installation of the

above applications. Investigate the remaining features of the

product support CD as described below, or click the Close button

to remove the window.

4. Remove and store the product support CD.

Figure 4.5 The Contents window of the product support CD

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View Documents The middle six buttons in the Contents window of the product support

CD give access to the documents stored on the CD:

■user’s guide

■service manual

■operator’s manual

■PCB information packs

■accessories manual

■licence agreement

To view any document click the corresponding button. The Adobe

Acrobat Reader application needs to be installed on the test PC.

Access TaitWorld

Website Of the two lower and remaining buttons in the Contents window of the

product support CD, the “Miscellaneous” button is currently unused.

Clicking the “TaitWorld” button opens the default browser installed on the

test PC and accesses the TaitWorld website.

Programming

Application The programming application is typically used to read the programming

file of a radio, change settings in the various forms constituting the file,

and reprogram the radio. Alternatively, the application can be used to

open a new file, select the required settings, and program one or more

radios. To run the application and become familiar with its features,

proceed as follows:

1. Click “Start” > “Programs” > “Tait Programming Applications” >

“TM8100 Programming Application”. The programming application

is opened.

2. On the menu bar, click “Help” > “Contents and Index”. The on-line

help facility is opened.

3. Read the information provided by the on-line help facility.

4. Close the on-line help facility and close the programming

application.

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Calibration Application The calibration application is used to read radio calibration files, perform

diagnostic functions, change certain settings, perform calibration tests,

view and check calculated calibration data, and program radios with

calibration files. To run the application and become familiar with its

features, proceed as follows:

1. Click “Start” > “Programs” > “Tait Programming Applications” >

“TM8100 Calibration Application”. The calibration application is

opened.

2. On the menu bar, click “Help” > “Contents and Index”. The on-line

help facility is opened.

3. Read the information provided by the on-line help facility.

4. Close the on-line help facility and close the calibration

application.

Computer-controlled

Test M od e The servicing procedures require a radio to be placed in the computer-

controlled test mode. In this mode CCTM commands can be entered at

the test PC. These commands are then relayed via the test unit to the

radio. Certain CCTM commands cause the radio to carry out particular

functions; others read particular settings and parameter values in the

radio. The CCTM commands of use in servicing radios are listed in

Table 4.5 to Table 4.9, grouped according to category.

Terminal Program

for CCTM To place a radio in CCTM requires the use of a terminal program on the

test PC. An example is HyperTerminal, which is supplied with

Microsoft Windows. As a preliminary, first select the settings for the

communications port as follows:

1. Open the terminal program. (In the case of HyperTerminal, click

“Start” > “Programs” > “Accessories” > “Communications” >

“HyperTerminal”.)

2. In the terminal program first select the COM port to which the

radio is connected. Then select the following settings for the port:

■bits per second : 19 200

■data bits : 8

■parity : none

■stop bits : 1

■flow control : none

3. Click the “OK” button (or equivalent).

4. Save the file with the port settings under a suitable name. For

subsequent sessions requiring the terminal program, open this file.

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Table 4.5 CCTM commands in the audio category

Command

Usage

Entry at keyboard Response on screen

Audio category

20 – Mute received audio

Forces muting of the received

audio signal

20 None

21 – Unmute received audio

Forces unmuting of the received

audio signal

21 None

22 – Mute microphone

Mutes transmit modulation

(effectively mutes microphone

audio)

22 None

23 – Unmute microphone

Unmutes transmit modulation

(effectively unmutes microphone

audio)

23 None

74 – Audio PA

Controls the state of the audio PA

(and hence enables or disables the

speaker)

74 x

where x is the required state

(0=stand-by, 1=on, 2=mute)

None

110 – Audio volume

Sets the level of the audio volume

110 x

where x defines the required level

(any integer from 0 to 255)

None

138 – Select microphone

Selects the microphone required

138 x

where x is the required microphone

(0=control-head microphone;

1=auxiliary microphone)

None

323 – Audio tap in

Generates the audio tone AUD TAP IN

at the specified tap point

323 x y

where x specifies the tap point

(r2, r5, t1 or t5) and y the tap type

(A=bypass in, B=combine, E=splice)

(the default is A when y is omitted)

None

324 – Audio tap out

Outputs the audio signal at the

specified tap point to AUD TAP OUT

324 x y

where x specifies the tap point

(r1, r2, r3, r4, r5, t1, t2, t3 or t7)

and y the tap type

(C=bypass out, D=split, E=splice)

(the default is D when y is omitted)

None

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Table 4.6 CCTM commands in the radio-information, radio-control and system categories

Command

Usage

Entry at keyboard Response on screen

Radio-information category

94 – Radio serial number

Reads the serial number of the

radio

94 x

where x is the serial number

(an eight-digit number)

96 – Firmware version

Reads the version number of the

radio firmware

96 QMA1F_x_y

where x is a three-character

identifier and y is an eight-digit

version number

97 – Boot-code version

Reads the version number of the

boot code

97 QMA1B_x_y

where x is a three-character

identifier and y is an eight-digit

version number

98 – FPGA version

Reads the version number of the

FPGA

98 QMA1G_x_y

where x is a three-character

identifier and y is an eight-digit

version number

133 – Hardware version

Reads the product code of the

radio body and the hardware

version number

133 x

where x is the product code

and y is the version number

(a four-digit number)

134 – FLASH serial number

Reads the serial number of the

FLASH memory

134 x

where x is the serial number

(a 16-digit hexadecimal number)

Radio-control category

400 – Select channel

Changes the current channel to

that specified

400 x (alternatively *x)

where x is a valid channel number

None

System category

46 – Supply voltage

Reads the supply voltage

46 x

where x is the supply voltage in

millivolts

203 – Clear system error

Clears the last recorded system

error

203 None

204 – Read system error

Reads the last recorded system

error and the associated data

204 SysErr: x

where x is the error number and

y represents the associated data

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Table 4.7 CCTM commands in the frequency-synthesizer and receiver categories

Command

Usage

Entry at keyboard Response on screen

Frequency-synthesizer category

72 – Lock status

Reads the lock status of the RF PLL,

FCL and LO2 respectively

72 x y z

where x is the RF PLL, y the FCL,

and z the LO2 lock status

(0=not in lock, 1=in lock)

101 – Radio frequencies

Sets the transmit and receive

frequencies to specified values

101 x y 0

where x is the transmit and y the

receive frequency in hertz

(any integer from 50 000 000 to

1000 000 000)

None

334 – Synthesizer power

Switches the frequency synthesizer

on or off via the DIG SYN EN line

334 x

where x is the required state

(0=off, 1=on)

None

335 – Synthesizer switch

Switches the transmit-receive

switch of the frequency synthesizer

on or off via the DIG SYN TR SW line

335 x

where x is the required state

(0=off, 1=on)

None

Receiver category

32 – Receive mode

Sets the radio in the receive mode

32 None

63 – RSSI level

Reads the averaged RSSI level

63 x

where x is the averaged level in

multiples of 0.1 dBm

376 – Front-end tuning

Sets or reads the tuning voltage for

the front-end circuitry of the

receiver

376 (to read voltage) x

where x is the front-end tuning

voltage in millivolts

376 x (to set voltage)

where x is the front-end tuning

voltage in millivolts

(any integer from 0 to 3000)

None

378 – Receiver output level

Reads the signal power at the

output of the channel filter

(the square of the amplitude)

378 x

where x is the signal power

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Table 4.8 CCTM commands in the transmitter category (part 1)

Command

Usage

Entry at keyboard Response on screen

Transmitter category

33 – Transmit mode

Sets the radio in the transmit mode

33 None

47 – Temperature

Reads the temperature in the

vicinity of the PAs

47 x

where x is the ADC value of the

tem-perature (an integer from 0 to

1023) and y is the corresponding

voltage in millivolts (a value from 0

to 1200 mV)

114 – Transmitter power

Sets or reads the transmitter power

setting (compare command 326)

114 (to read value) x

where x is the current power

setting (an integer from 0 to 1023)

114 x (to set value)

where x is the required power

setting (an integer from 0 to 1023)

None

304 – Driver bias

Sets or reads the clamp current at

the gate of the PA driver

304 (to read value) x

where x is the DAC value of the

clamp current (an integer from 0 to

255)

304 x (to set value)

where x is the required DAC value

of the clamp current

(an integer from 0 to 255)

None

318 – Forward power

Reads the forward-power level

318 x

where x is the voltage in millivolts

corresponding to the power level

(a value from 0 to 1100 mV)

319 – Reverse power

Reads the reverse-power level

319 x

where x is the voltage in millivolts

corresponding to the power level

(a value from 0 to 1100 mV)

326 – Transmitter power

Sets the power level of the

transmitter

326 x

where x specifies the level

(0=off, 1=very low, 2=low,

3=medium, 4=high, 5=maximum)

None

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Invoking CCTM Using the terminal program, place the radio in CCTM as follows:

1. Enter the character ^ to reset the radio.

2. As soon as the radio is reset, the letter v is displayed. (If an

uppercase letter V appears, this implies a fault.)

3. Immediately the letter v is displayed, enter the character %. (The

character % must be entered within half a second of the letter v

appearing.)

4. If the character % is accepted, the character – is displayed in

response, and the message CL (two-digit display) or C (one-digit

display) appears on the radio’s LCD screen. This implies that the

radio has entered CCTM. If the attempt fails, repeat Steps 1 to 3.

CCTM Error Codes Once the radio is in CCTM, the CCTM commands may be entered as

shown in Table 4.5 to Table 4.9. Depending on the command, a

response might or might not be displayed. If an error occurs, an error

code will be displayed. Possible error codes are listed in Table 4.10.

Table 4.9 CCTM commands in the transmitter category (part 2)

Command

Usage

Entry at keyboard Response on screen

Transmitter category

331 – Final bias 1

Sets or reads the bias voltage for

the first PA

331 (to read value) x

where x is the DAC value of the

bias voltage (an integer from 0 to

255)

331 x (to set value)

where x is the DAC value of the

required bias voltage

(any integer from 0 to 255)

None

332 – Final bias 2

Sets or reads the bias voltage for

the second PA

332 (to read value) x

where x is the DAC value of the

bias voltage (an integer from 0 to

255)

332 x (to set value)

where x is the DAC value of the

required bias voltage

(any integer from 0 to 255)

None

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Visual and Aural

Indications In radios that have a control head with UI, visual and aural indicators give

information about the state of the radio. Visual indications are provided

by the STATUS LEDs, function-key LEDs, and LCD screen on the front

panel. The information conveyed by the STATUS LEDs is listed in

Table 4.11. The behaviour of the function-key LEDs depends on the

way the function keys are programmed; further information is not

appropriate in this manual. The LCD screen normally displays only the

number of the channel to which the radio is tuned. Other displays will

be mentioned where necessary but are not summarised here. Aural

indications are provided in the form of different tones emitted from the

speaker. The information conveyed by the tones is given in Table 4.12.

Not all of the tones listed are relevant to the servicing of radios but they

are included for the sake of completeness.

Table 4.10 CCTM error codes

Error code Description

C01 An invalid CCTM command has been received. Enter a valid CCTM command.

C02 A valid CCTM command with invalid parameters has been received. Re-enter the CCTM

command with valid parameters.

C03 A valid CCTM command has been received but cannot be processed at this time. Enter the

CCTM command again. If the error persists, power the radio down and up again, and re-enter

the CCTM command.

C04 An error occurred on entry into CCTM. Power the radio down and up again, and place the

radio in CCTM again.

C05 The radio has not responded within the specified time. Re-enter the CCTM command.

X04 The DSP is not responding. Check the DSP pin connections. If the error persists, replace the

DSP.

X05 The version of the DSP is incompatible with the version of the radio firmware. Replace the DSP

with a later version.

X06 The internal configuration of the MCU is incorrect. Adjust the configuration.

X31 There is an error in the checksum for the model configuration.

X32 There is an error in the checksum for the radio’s database.

X35 The radio temperature is above the T1 threshold and a reduction in the transmit power is

impending. To avoid damaging the radio, stop transmitting until the radio has cooled down

sufficiently.

X36 The radio temperature is above the T2 threshold and the inhibiting of transmissions is

imminent.

X37 The supply voltage is less than the V1 threshold.

X38 The supply voltage is less than the V2 threshold and the radio has powered itself down. The

radio will not respond to the reset command character ^.

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Table 4.11 Visual indications provided by the STATUS LEDs of control heads with UI

LED colour LED name Indications Meanings

Red Transmit LED is on The radio is transmitting

LED flashes (1) The transmit timer is about to expire

(2) The radio has been stunned

Green Receive and

monitor

LED is on There is activity on the current channel, although it might

not be audible

LED flashes (1) The radio has received a call with valid special signalling

(2) The monitor has been activated

(3) The squelch override has been activated

Amber Scanning LED is on The radio is scanning a group of channels for activity

LED flashes The radio has detected activity on a certain channel and

scanning has halted on this channel

Table 4.12 Aural indications emitted from the speaker of control heads with UI

Type of tone Meanings

One short beep (1) After power-up — Radio is locked; PIN is required

(2) On power-down — Radio is off

(3) On pressing key — Key-press is valid

(4) On pressing function key — Function has been initiated

One short low-pitched beep On pressing function key again — Function has been terminated

One short high-pitched beep While powered up — Radio has been stunned

One long low-pitched beep (1) On pressing key — Key-press is invalid

(2) On entry of PIN — PIN is invalid

(3) On pressing PTT switch — Transmission is inhibited

Two short beeps (1) On power-up — Radio is ready to use

(2) On entry of PIN — PIN has been accepted and radio is ready to use

(3) After radio has been stunned — Radio has been revived and is ready to use

Two low-pitched beeps While powered up — Temperature of radio is high

Two high-pitched beeps While powered up — Temperature of radio is very high and all transmissions

will be at low power; if temperature rises further, transmissions will be inhibited

Three short beeps While powered up — Previously busy channel is now free

Three beeps During transmission — Transmit time-out is imminent; transmission will be

terminated in 10 seconds

Warble While powered up — Frequency synthesizer is out of lock on current channel;

LCD will usually be flashing OL (two-digit display) or L (one-digit display)

Continuous low-pitched

tone

While powered up — System error has occurred and radio might be inoperable;

LCD usually displays E1 or E2 (two-digit display) or E (one-digit display)

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TM8100 Mobile Radio Service Manual Servicing Procedure 107

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5 Servicing Procedure

Scope of Section This section gives the full sequence of tasks required when servicing a

particular radio. These tasks are:

■initial inspection

■fault diagnosis and repair

■final inspection, test and administration

The tasks are described in Subsection 5.1 to Subsection 5.3 respectively.

Where more details are required regarding disassembly and re-assembly

procedures, references are given to Section 6 (on page 125). For the

servicing of the control head and main board, references are given to

Section 7 (on page 151) and Section 8 (on page 165) respectively.

5.1 Initial Inspection

Introduction When a radio is received for repair, details of the Customer and the fault

will be recorded in a fault database. The fault reported by the Customer

might concern damage to or loss of a mechanical part, or the failure of a

function of the radio, or both. Whatever the case, first check the radio

for mechanical loss or damage. This is advisable even if the fault

concerns a function failure only. Inspect the radio as follows:

Check for Minor

Damage or Loss Check for damage or loss of parts that can be replaced without

disassembling the radio. These parts are:

■knob for volume-control potentiometer

■microphone grommet

■rubber seal for RF connector

■bung for auxiliary connector

■bung for aperture for external options connector

The last-named part should be replaced by a cover seal if an external

options connector is present. All the parts are illustrated in

Subsection 2.1 (on page 33). Except for the microphone grommet, if

any of these parts is missing or damaged, replace it as described below.

In the case of the microphone grommet, refer to the accessories manual

for the repair procedure.

Replace Damaged

or Missing Knob Remove the volume-control knob if it is damaged. Obtain a

replacement knob from Spares kit 1 or 10. The contents of the kit are

listed in Table 6.1 of Section 6 (on page 125). Push the replacement

knob onto the shaft of the volume-control potentiometer. Ensure that

the knob turns freely.

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Replace Damaged

or Missing Seals

and Bungs

Remove any damaged seal or bung. Obtain a replacement seal for the

RF connector or a replacement bung from Spares kit 2. The contents of

the kit are listed in Table 6.2 of Section 6 (on page 125). Order a

replacement cover seal (and screws) from TEL; the IPNs of the parts are

listed in Table 2.2. In fitting a replacement bung, ensure that it is not

upside down and that it is properly seated. To fit the seal for the RF

connector, first fit the upper part of the seal and then press down around

the sides of the seal to the bottom. Ensure that the seal is properly seated

around its entire periphery.

Check for

Additional Damage Also check for damage to exterior parts that can be replaced only by

partly disassembling the radio. These parts are:

■cover assembly for radio body

■keys, lens and LCD of control head

■front panel of control head

In the case of the front panel, inspect particularly the light pipes for the

STATUS LEDs and the membrane behind the speaker grille. If the radio

is reported to have a functional fault, continue with the tasks given in

Subsection 5.2 (on page 109) — any additional mechanical damage will

be repaired during the course of rectifying the functional fault. If the

radio has no functional fault, repair any additional damage as described

below; conclude with the tasks of Subsection 5.3 (on page 121).

Replace Damaged

Cover Assembly Remove a damaged cover assembly as described in Subsection 6.3

(on page 137). Obtain a replacement assembly from Spares kit 2. The

cover assembly comprises a cover and a label, as shown in Figure 2.8; the

label is permanently fixed to the cover. The IPNs of both items are given

in Table 6.2. If a spares kit is not available, order both items from TEL.

Fit the replacement cover assembly to the radio body.

Repair Damaged

Control Head If the control head is damaged, detach it from the radio body as described

in Subsection 6.1 (on page 127). The procedure includes inspecting the

interior of the control head for evidence of other damage. Disassemble

the control head and repair all damage as described in Subsection 6.2

(on page 131). Obtain replacement parts from Spares kit 1 (two-digit-

display control head) or Spares kit 10 (one-digit-display control head).

Then re-assemble the control head and re-attach it to the radio body as

described in Subsection 6.5 (on page 148).

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5.2 Fault Diagnosis and Repair

List of Tasks When the radio is reported to have a functional fault, carry out the tasks

described in this section. There are seven possible tasks in all:

■Task 1 — power up radio

■Task 2 — read programming file

■Task 3 — obtain SFE (software feature enabler) details

■Task 4 — read calibration file

■Task 5 — check user interface

■Task 6 — check receive and receive-audio functions

■Task 7 — check transmit and transmit-audio functions

Only the task relevant to the reported fault needs to be carried out,

except that the first four tasks must always be done. If the report of the

fault is not sufficiently specific, all the tasks must be done. If the fault is

not confirmed when the relevant task is done, obtain more information

from the Customer; in particular, determine whether the radio is

properly configured for the Customer’s system.

Tas k 1 —

Power up Radio With the radio connected to the test equipment as described in

Subsection 4.5 (on page 93), attempt to power up the radio:

1. Apply power to the radio. If the radio doesn’t power up

automatically, press the ON/OFF switch.

2. If the radio powers up successfully, proceed to Task 2. If it does

not, attempt to rectify the fault as described in the chart of

Figure 5.1.

3. If the repair succeeded — without the need for replacing the

main-board assembly — proceed to Task 2. Otherwise continue

with Step 4.

4. If the main-board assembly was replaced or if the repair failed, re-

assemble the radio as described in Subsection 6.4 (on page 144)

and Subsection 6.5 (on page 148). Conclude with the tasks of

Subsection 5.3 (on page 121).

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POWER-UP FAULTS

1. Initial checks

(1) If the radio fails to power up properly, check the fuses, cables, connectors, mains plug,

and DC power supply. Rectify any fault. (If a fuse has blown, replace it with exactly

the same type of fast-blow fuse.)

(2) Check if the radio powers up.

(3) If the radio powers up, return to Step 3 of Task 1. If it does not, go to (4) below.

(4) Detach the control head as in Subsection 6.1 (on page 127), and exchange it for a

serviceable spare control head.

(5) Check if the radio powers up.

(6) If the radio powers up, the original control head is faulty; disconnect the spare control

head, and go to Part 2 below. If the radio still fails to power up, the radio body is

faulty; reconnect the original control head, and go to Part 3.

2. Control head faulty

(1) Exchange the control-head loom for a serviceable spare loom.

(2) Check if the radio powers up.

(3) If the radio powers up, the original loom is faulty; go to (4). If the radio still fails to

power up, reconnect the original loom, and go to (5).

(4) Replace the faulty control-head loom, and return to Step 3 of Task 1.

(5) Check the control-head connector on the control-head board.

(6) If the connector is faulty, remove the control-head board as in Subsection 6.2

(on page 131), and replace the connector. If the connector is not faulty, replace the

control-head board as in Subsection 7.4 (on page 163).

(7) Check if the radio powers up.

(8) If the radio powers up, return to Step 3 of Task 1. If the radio does not power up, the

repair has failed; re-assemble the control head with the original control-head board as

in Subsection 6.5 (on page 148), and return to Step 3 of Task 1.

3. Radio body faulty

(1) Remove the lid of the radio body as in Subsection 6.3 (on page 137), and check the

power connector.

(2) If the connector is not faulty, go to (5). If it is, go to (3).

(3) At level-1 service centres, go to (5) and replace the main-board assembly. At level-2

service centres, remove and disassemble the main-board assembly as in Subsection 6.3,

replace the connector, and re-assemble the main-board assembly as in Subsection 6.4

(on page 144).

(4) Check if the radio powers up. If it does, return to Step 3 of Task 1. If it does not, go to

(5).

(5) Repair or replace the main-board assembly as in Section 8 (on page 165).

(6) The final test in Section 8 will indicate whether the repair succeeded or failed. Return

to Step 3 of Task 1.

Figure 5.1 Chart for locating and rectifying faults that affect power up

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Tas k 2 —

Read Programming File Given that the radio powers up, the next task is to read the radio’s

programming file or upload a default file.

1. Run the programming application on the test PC as described in

Subsection 4.5 (on page 93).

2. Attempt to read the radio’s programming file. If it seems that the

file cannot be read, cycle the power to the radio and again attempt

to read the file. First cycling the power is essential if the radio is

programmed to power up in transparent-data mode (both

1200 baud FFSK and Tait high-speed data) and if the selected data

port is the microphone connector (control head with UI) or

programming connector (blank control head).

3. If the file can be read, store a copy on the test PC and proceed to

Task 3. If the file cannot be read, attempt to rectify the fault as

described in the chart of Figure 5.2.

4. If the repair succeeded — without the need for replacing the

main-board assembly — continue with Step 5. Otherwise

continue with Step 8.

5. If the programming file can be read now, store a copy on the test

PC and proceed to Task 3. If the file still cannot be read, set up a

default programming file.

6. Attempt to upload the default programming file to the radio.

7. If the upload succeeds, proceed to Task 4. If the upload fails,

continue with Step 8.

8. If the main-board assembly was replaced or if the repair failed, re-

assemble the radio as described in Subsection 6.4 (on page 144)

and Subsection 6.5 (on page 148). Conclude with the tasks of

Subsection 5.3 (on page 121).

Tas k 3 —

Obtain SFE Details Determine if any software features have been enabled for the radio under

repair.

1. Use the programming application to obtain details of software

features. On the menu bar click “Tools” > “Optional Features”. The

“Software Feature Enabler” dialogue box appears.

2. In the dialogue box all available features are listed in the “Feature

Set” field. The corresponding product codes are given in the

“Feature Code” field.

3. Click the “Read Radio” button.

4. The status of each feature listed — whether enabled or disabled —

is shown in the “Status” field. Note if any features are enabled.

112 Servicing Procedure TM8100 Mobile Radio Service Manual

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PROGRAMMING FAULTS

1. Initial checks

(1) If the radio’s programming file cannot be read, check the connections between the test

PC and the radio, the cables, the test unit, and that the serial port of the test PC is

correct. (It is good practice to set the MODE switch on the test unit to “RX”.) Rectify any

fault.

(2) Check if the programming file can be read.

(3) If the file can be read, return to Step 4 of Task 2. If it cannot be read, go to (4) below.

(4) Detach the control head as in Subsection 6.1 (on page 127), and exchange it for a

serviceable spare control head.

(5) Check if the programming file can be read.

(6) If the file can be read, the original control head is faulty; disconnect the spare control

head, and go to Part 2 below. If the file still cannot be read, the radio body is faulty;

reconnect the original control head, and go to Part 3.

2. Control head faulty

(1) If the control-head loom has already been checked, go to (5). If it has not, exchange

the loom for a serviceable spare loom.

(2) Check if the programming file can be read.

(3) If the file can be read, the original loom is faulty; go to (4). If the file still cannot be

read, reconnect the original loom, and go to (5).

(4) Replace the faulty control-head loom, and return to Step 4 of Task 2.

(5) Check the control-head connector and microphone connector on the control-head

board and the path between them.

(6) If either connector is faulty, remove the control-head board as in Subsection 6.2

(on page 131), and replace the connector. If there is an obvious fault causing a break

in the path between the connectors, repair it. If no fault can be found, replace the

control-head board as in Subsection 7.4 (on page 163).

(7) Check if the programming file can be read.

(8) If the file can be read, return to Step 4 of Task 2. If the file cannot be read, re-assemble

the control head with the original control-head board, and return to Step 4 of Task 2.

3. Radio body faulty

(1) Remove the lid of the radio body as in Subsection 6.3 (on page 137).

(2) Repair or replace the main-board assembly as in Section 8 (on page 165).

(3) The final test in Section 8 will indicate whether the repair succeeded or failed. Return

to Step 4 of Task 2.

Figure 5.2 Chart for locating and rectifying faults that affect the reading of the programming file

TM8100 Mobile Radio Service Manual Servicing Procedure 113

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Tas k 4 —

Read Calibration File Given that the programming file can be read, or a default programming

file uploaded, the next task is to read the calibration file.

1. Run the calibration application on the test PC as described in

Subsection 4.5 (on page 93).

2. Attempt to read the radio’s calibration file. (If the radio is

programmed to power up in transparent-data mode as discussed in

Task 2, first cycle the power to the radio.)

3. If the file can be read, store a copy on the test PC and proceed to

the next paragraph. If the file cannot be read, set up a suitable

default calibration file.

4. Upload the default calibration file. This should be successful

because any faults affecting this task should have been rectified in

Ta s k 2.

Remaining Tasks Further action depends on the nature of the reported fault. There are

five possibilities:

1. If the reported fault concerns powering up the radio — and this

has now been addressed — servicing of the radio is complete. Re-

assemble the radio, if necessary, and conclude with the tasks of

Subsection 5.3 (on page 121).

2. If the reported fault concerns reading the programming file — and

this has now been addressed — servicing of the radio is complete.

Re-assemble the radio, if necessary, and conclude with the tasks of

Subsection 5.3.

3. If the reported fault concerns the user interface or a receive or

transmit function, carry out only the relevant task below.

4. If the reported fault is unspecific, carry out each of the remaining

tasks in sequence.

5. If the reported fault concerns powering up the radio or reading

the programming file, and this has not been confirmed, obtain

more information from the Customer.

114 Servicing Procedure TM8100 Mobile Radio Service Manual

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Task 5 —

Check User Interface This task does not apply to the blank control head. Check the user

interface of one- and two-digit-display control heads as follows:

1. Check for any of the following faults:

■LCD faulty

■some or all LEDs faulty

■some or all keys faulty

■speaker faulty

■volume control faulty

In the case of the function-key LEDs, note from the programming

file whether the back-lighting option is on or off.

2. If there is no fault, continue with Step 6. If there is a fault,

continue with Step 3.

3. Attempt to rectify the fault as described in Section 7

(on page 151). The final test in Section 7 will indicate whether

the repair succeeded or failed.

4. If the repair succeeded, continue with Step 5. If the repair failed,

conclude with the tasks of Subsection 5.3 (on page 121).

5. If the reported fault is unspecific, proceed to Task 6. If the

reported fault concerns the user interface — and this has now

been rectified — re-assemble the radio, if necessary, and conclude

with the tasks of Subsection 5.3.

6. If the reported fault concerns the user interface — and this has not

been confirmed — obtain more information from the Customer.

If the reported fault is unspecific, proceed to Task 6.

TM8100 Mobile Radio Service Manual Servicing Procedure 115

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Tas k 6 —

Check Receive and

Receive-audio

Functions

Check the receive and receive-audio functions of the radio as follows:

1. Check whether the radio receives.

2. If the radio receives, continue with Step 7. If it does not, continue

with Step 3.

3. Attempt to rectify the fault as described in the charts of Figure 5.3

and Figure 5.4.

4. If the repair succeeded — without the need for replacing the

main-board assembly — continue with Step 6. Otherwise

continue with Step 5.

5. If the main-board assembly was replaced or if the repair failed, re-

assemble the radio as described in Subsection 6.4 (on page 144)

and Subsection 6.5 (on page 148). Conclude with the tasks of

Subsection 5.3 (on page 121).

6. If the reported fault concerns the receive function — and this has

now been rectified — re-assemble the radio, if necessary, and

conclude with the tasks of Subsection 5.3. If the reported fault is

unspecific, proceed to Task 7.

7. If the reported fault concerns the receive function — and this has

not been confirmed — obtain more information from the

Customer. If the reported fault is unspecific, proceed to Task 7.

116 Servicing Procedure TM8100 Mobile Radio Service Manual

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RECEIVE AND RECEIVE-AUDIO FAULTS — PARTS 1 AND 2

1. Initial checks

(1) If the radio fails to receive, detach the control head as in Subsection 6.1 (on page 127),

and exchange it for a serviceable spare control head.

(2) Check if the radio receives.

(3) If the radio receives, the original control head is faulty; disconnect the spare control

head, and go to Part 2 below. If the radio still fails to receive, the radio body is faulty;

reconnect the original control head, and go to Part 3 in Figure 5.4.

2. Control head faulty

(1) If the control-head loom has already been checked, go to (5). If it has not, exchange

the loom for a serviceable spare loom.

(2) Check if the radio receives.

(3) If the radio receives, the original loom is faulty; go to (4). If the radio still fails to

receive, reconnect the original loom, and go to (5).

(4) Replace the faulty control-head loom, and return to Step 4 of Task 6.

(5) If the speaker and volume control have already been checked, go to (8). If they have

not, check if either is faulty. If there is no fault, go to (8). If there is a fault, repair it as

in Subsection 7.1 (on page 151).

(6) If the repair succeeded, go to (7). If the repair failed, return to Step 4 of Task 6.

(7) Check if the radio receives. If it does, return to Step 4 of Task 6. If it does not, go to

(8).

(8) Check the control-head connector and microphone connector on the control-head

board and the path between them.

(9) If either connector is faulty, remove the control-head board as in Subsection 6.2

(on page 131), and replace the connector. If there is an obvious fault causing a break

in the path between the connectors, repair it. If no fault can be found, replace the

control-head board as in Subsection 7.4 (on page 163).

(10) Check if the radio receives.

(11) If the radio receives, return to Step 4 of Task 6. If the radio still fails to receive, re-

assemble the control head with the original control-head board, and return to Step 4

of Task 6.

Figure 5.3 Chart for locating and rectifying faults that affect the receive function — control head is

faulty

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RECEIVE AND RECEIVE-AUDIO FAULTS — PART 3

3. Radio body faulty

(1) Enter the CCTM command 72 to check if the radio is in lock.

(2) If the radio is in lock, go to (6). If it is not, check the programming file, and in

particular the frequency band and channel frequencies.

(3) If the programming file is OK, go to (13). If it is not, reprogram the radio.

(4) Check if the radio is in lock. If it is, go to (5). If it is not, go to (13).

(5) Check if the radio receives. If it does, return to Step 4 of Task 6. If it does not, go to

(6).

(6) Check the receiver sensitivity. If the sensitivity is OK, go to (7). If it is not, go to (9).

(7) Check the squelch function. If it is OK, go to (9). If it is not, recalibrate the radio.

(8) Check if the radio receives. If it does, return to Step 4 of Task 6. If it does not, go to

(9).

(9) Remove the lid of the radio body as in Subsection 6.3 (on page 137), and check the RF

connector.

(10) If the connector is OK, go to (13). If it is faulty, go to (11).

(11) At level-1 service centres, go to (13) and replace the main-board assembly. At level-2

service centres, remove and disassemble the main-board assembly as in Subsection 6.3,

replace the connector, and re-assemble the main-board assembly as in Subsection 6.4

(on page 144).

(12) Check if the radio receives. If it does, return to Step 4 of Task 6. If it does not, go to

(13).

(13) Repair or replace the main-board assembly as in Section 8 (on page 165).

(14) The final test in Section 8 will indicate whether the repair succeeded or failed. Return

to Step 4 of Task 6.

Figure 5.4 Chart for locating and rectifying faults that affect the receive function — radio body is

faulty

118 Servicing Procedure TM8100 Mobile Radio Service Manual

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Task 7 —

Check Transmit and

Transmit-audio

Functions

Check the transmit and transmit-audio functions of the radio as follows:

1. Check whether the radio transmits.

2. If the radio transmits, continue with Step 5. If it does not,

continue with Step 3.

3. Attempt to rectify the fault as described in the charts of Figure 5.5

and Figure 5.6.

4. Re-assemble the radio, if necessary. Conclude with the tasks of

Subsection 5.3 (on page 121).

5. If the reported fault concerns the transmit function — and this has

not been confirmed — obtain more information from the

Customer. If the reported fault is unspecific, and no fault could

be found with the radio, also obtain more information. Otherwise

re-assemble the radio, if necessary, and conclude with the tasks of

Subsection 5.3.

TM8100 Mobile Radio Service Manual Servicing Procedure 119

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TRANSMIT AND TRANSMIT-AUDIO FAULTS — PARTS 1 AND 2

1. Initial checks

(1) If the radio fails to transmit, exchange the microphone for a serviceable spare

microphone.

(2) Check if the radio transmits.

(3) If the radio transmits, the original microphone is faulty; go to (4). If the radio still fails

to transmit, reconnect the original microphone, and go to (5).

(4) Repair the faulty microphone as described in the accessories manual, and return to

Step 4 of Task 7.

(5) Detach the control head as in Subsection 6.1 (on page 127), and exchange it for a

serviceable spare control head.

(6) Check if the radio transmits.

(7) If the radio transmits, the original control head is faulty; disconnect the spare control

head, and go to Part 2 below. If the radio still fails to transmit, the radio body is faulty;

reconnect the original control head, and go to Part 3 in Figure 5.6.

2. Control head faulty

(1) If the control-head loom has already been checked, go to (5). If it has not, exchange

the loom for a serviceable spare loom.

(2) Check if the radio transmits.

(3) If the radio transmits, the original loom is faulty; go to (4). If the radio still fails to

transmit, reconnect the original loom, and go to (5).

(4) Replace the faulty control-head loom, and return to Step 4 of Task 7.

(5) Check the control-head connector and microphone connector on the control-head

board and the path between them.

(6) If either connector is faulty, remove the control-head board as in Subsection 6.2

(on page 131), and replace the connector. If there is an obvious fault causing a break

in the path between the connectors, repair it. If no fault can be found, replace the

control-head board as in Subsection 7.4 (on page 163).

(7) Check if the radio transmits.

(8) If the radio transmits, return to Step 4 of Task 7. If the radio still fails to transmit, re-

assemble the control head with the original control-head board, and return to Step 4

of Task 7.

Figure 5.5 Chart for locating and rectifying faults that affect the transmit function — control head

is faulty

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TRANSMIT AND TRANSMIT-AUDIO FAULTS — PART 3

3. Radio body faulty

(1) If the radio transmits a carrier but not audio, go to (7).

(2) Enter the CCTM command 72 to check if the radio is in lock.

(3) If the radio is in lock, go to (7). If it is not, check the programming file, and in

particular the frequency band and channel frequencies.

(4) If the programming file is OK, go to (7). If it is not, reprogram the radio.

(5) Check if the radio is in lock. If it is, go to (6). If it is not, go to (7).

(6) Check if the radio transmits. If it does, return to Step 4 of Task 7. If it does not, go to

(7).

(7) Remove the lid of the radio body as in Subsection 6.3 (on page 137), and check the RF

connector.

(8) If the connector is OK, go to (11). If it is faulty, go to (9).

(9) At level-1 service centres, go to (11) and replace the main-board assembly. At level-2

service centres, remove and disassemble the main-board assembly as in Subsection 6.3,

replace the connector, and re-assemble the main-board assembly as in Subsection 6.4

(on page 144).

(10) Check if the radio transmits. If it does, return to Step 4 of Task 7. If it does not, go to

(11).

(11) Repair or replace the main-board assembly as in Section 8 (on page 165).

(12) The final test in Section 8 will indicate whether the repair succeeded or failed. Return

to Step 4 of Task 7.

Figure 5.6 Chart for locating and rectifying faults that affect the transmit function — radio body is

faulty

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5.3 Final Inspection, Test and Administration

Remaining Tasks This subsection discusses the servicing tasks remaining after the repair, or

attempted repair, of the radio:

■final inspection

■final test

■final administration

If the radio could not be repaired, omit the first two tasks.

Final Inspection After repairing and re-assembling the radio, make a final inspection of the

exterior to check that no mechanical parts were damaged during the

repair. Repeat the inspection given in Subsection 5.1 (on page 107).

Rectify any damage.

Final Test Reconnect the radio to the test equipment. Test the radio to confirm

that it is fully functional again. The recommended tests are listed in

Table 5.1 to Table 5.3. (The calibration application can be used for

many of these tests.) It is good practice to record the test results on a

separate test sheet. A copy of the test sheet can be supplied to the

Customer as confirmation of the repair.

Final Administration The administration tasks following a successful repair of the radio are

discussed in the next paragraph. There will be cases, on the other hand,

where the radio could not be repaired for one of the following reasons:

■fault not located

■repair of fault failed

■required repair is level-3 repair

In these cases level-1 service centres should return the faulty radio to the

nearest ASC, and level-2 service centres should return the radio to the

ISC. Supply details of the Customer, the fault and, if applicable, the

attempted repair.

Administration Tasks The final administration tasks are the standard workshop procedures for

updating the fault database and returning the repaired radio to the

Customer with confirmation of the repair. With TM8100 radios,

however, additional tasks are necessary if:

■faulty control-head board or main-board assembly is replaced

■default programming file is used

These additional tasks are discussed further below.

122 Servicing Procedure TM8100 Mobile Radio Service Manual

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Replacement of

Board or Assembly In some cases the repair of the radio will require the replacement of a

complete control-head board or a complete main-board assembly. In

these cases level-1 service centres should return the faulty board or

assembly to the nearest ASC, and level-2 service centres should return

the board or assembly to the ISC. Supply details of the fault and, if

applicable, the attempted repair.

New Programming File If the radio had to be reprogrammed with a default programming file, the

following additional actions are required: If the radio is to be returned

direct to a Customer who has no programming facilities, the appropriate

programming file needs to be obtained and uploaded (or the data

obtained to create the file). If the radio is to be returned to a Dealer or

direct to a Customer who does have programming facilities, the Dealer

or Customer respectively need to be informed so that they can program

the radio appropriately.

Table 5.1 Final tests of transmitter function

Test Limits

Error in transmit frequency +100 Hz to –100 Hz

Transmit power:

• High

• Medium

• Low

• Very low

23.2 W to 29.2 W

11.1 W to 14.0 W

4.6 W to 5.8 W

0.9 W to 1.2 W

Current at high power:

• B1-band radios

• D1-band radios

• H5-band radios

• H6-band radios

< 5.5 A

< 6.5 A

Peak deviation (sweep tone of 300 Hz to 3 kHz):

• Narrow-band

• Medium-band

• Wide-band

< 2.5 kHz

< 4.0 kHz

< 5.0 kHz

Distortion:

• 1 kHz at 1.5 kHz deviation (narrow-band)

• 1 kHz at 3.0 kHz deviation (wide-band)

< 3%

CTCSS (continuous-tone-controlled subaudible signalling) deviation:

• Narrow-band

• Medium-band

• Wide-band

250 to 350 Hz

500 to 560 Hz

580 to 680 Hz

TM8100 Mobile Radio Service Manual Servicing Procedure 123

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Table 5.2 Final tests of receiver functions

Test Limits

Receive sensitivity <118 dBm for 12 dB SINAD

Mute opening:

• Country

• City

• Hard

>6 dB and <10 dB SINAD

>8 dB and <14 dB SINAD

>18 dB and <22 dB SINAD

Audio power (maximum volume at –47 dBm):

• At “RX AUDIO/SINAD” connector on test unit

• At pins 3 (SPK–) and 4 (SPK+) of power connector on radio

>500 mVrms

>5.00 Vrms

Distortion (at –47 dBm, 60% rated system deviation at 1 kHz,

with volume set to give 3 W into 16 Ω load) <3.00%

Table 5.3 Final tests of general radio functions

Test Description

PTT switch Check that PTT switch functions

Microphone Check operation of microphone

Check operation of hook-switch

Data communications Test 1200 baud data transmission (standard)

Test Tait high-speed data transmission (if feature is enabled)

Direct-connect GPS

(global positioning system)

Check that GPS poll returns correct position (if feature is enabled)

Selcall Check that radio encodes selcall

Check that radio decodes selcall

Audio tap points and digital I/O Check configuration of programmed options and test operation of

these lines to confirm that Customer requirements are satisfied

124 Servicing Procedure TM8100 Mobile Radio Service Manual

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TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 125

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6 Disassembly and Re-assembly of Radio

Introduction This section covers the procedures for disassembling and re-assembling

the radio:

■detachment of control head

■disassembly of control head

■disassembly of radio body

■re-assembly of radio body

■re-assembly and attachment of control head

The procedures are detailed in Subsection 6.1 to Subsection 6.5

respectively.

References to

Disassembly and Re-

assembly Procedures

The full sequence of tasks entailed in servicing the radio is given in

Subsection 5.2 (on page 109). During the course of servicing a

particular radio, some or all of the above disassembly and re-assembly

procedures will be required. In Subsection 5.2 there are instructions at

the appropriate points regarding which disassembly or re-assembly

procedure needs to be carried out. However, these procedures can also

be followed independently to disassemble and re-assemble the radio.

126 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.1 Lever points for detaching the control head from the radio body

LEVER

POINT

DETAILS OF

LEVER POINT

INDICATION OF

LEVER POINT

UNDERSIDE OF CHASSIS CONTROL HEAD

RADIO

BODY

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 127

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6.1 Detachment of Control Head

Detach Control Head Whether the control head or the radio body is faulty, the control head

needs to be detached from the radio body. Do so as follows:

1. Note which way up the control head is attached to the radio body.

The control head may be oriented with the underside of the radio

body either facing up or facing down. The configuration depends

on the Customer’s installation, and the radio will need to be

returned to the Customer with the same configuration.

2. Disconnect the radio from any test equipment or power supply.

3. Note the two points where the control head should be levered off

the radio body. As shown in Figure 6.1, these points are indicated

by dot-dash-dot marks on the underside of the radio body. The

lever point is between the rubber control-head seal and the front

panel of the control head.

4. At each of the above lever points, insert the blade of a medium-

sized (about 5 mm) flat-bladed screwdriver and lever off the

control head.

5. After detaching the control head, disconnect the control-head

loom at the connector on the radio body. Refer to Figure 6.2.

6. Inspect the control head and loom as described below.

128 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.2 Details of the control-head seal between the radio body and control head

CONTROL-HEAD LOOM

CONTROL HEAD

CONTROL-HEAD

SEAL

RADIO BODY

SEAL

SEAL LIPS

FRONT FACE OF RADIO BODY

DETAILS OF

CONTROL-HEAD SEAL

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 129

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Inspect Mechanical

Parts Regardless of the reason for detaching the control head, it is advisable to

inspect the mechanical parts for damage. Any exterior damage will have

been identified already in Subsection 5.1 (on page 107). Check for and

rectify any interior damage as follows:

1. Inspect the control-head loom. If the loom has obvious physical

damage, replace it with a spare loom from Spares kit 1 (two-digit

display) or Spares kit 10 (one-dig it display). The product code and

contents of the kit are listed in Subsection 6.2 (on page 131).

2. Inspect the control-head seal. Refer to Figure 6.2, which shows

a cross-section of the seal. Check for any sign of deformation, cuts

or tears. Pay particular attention to the two lips of the seal.

3. If the seal is damaged, replace it with a spare seal from Spares kit

7. This kit contains a set of these seals.

4. Inspect the interior of the control head for signs of damage.

Check for cracked, broken or burnt parts. In a control head with

UI the parts to inspect are the space-frame, speaker and, if fitted,

concealed microphone. In a blank control head inspect the

programming connector and attached loom.

5. If the inspection in Step 4 reveals no damage, continue with the

repair of the radio as described in Subsection 5.2 (on page 109).

If there is damage in a control head with UI, disassemble the

control head and replace the damaged part or assembly as

described in the next subsection. If there is damage in a blank

control head, replace the complete control head; for the relevant

product code refer to Subsection 1.5 (on page 26).

130 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.3 Plan view of the control head showing the control-head board

CONCEALED MICROPHONE

(IF FITTED)

GUIDE 3

CLIP 3

SCREW 1 CLIP 1 CLIP 2

PADS FOR LEADS TO

CONCEALED MICROPHONE

SPEAKER

CONNECTOR

CONTROL-HEAD

BOARD

SPEAKER

CONTROL-HEAD

CONNECTOR

SCREW 3 GUIDE 4SCREW 2GUIDE 1GUIDE 2

POSITION OF CIRCUIT

BOARD FOR OPTIONAL

MICROPHONES

CONNECTORS FOR

OPTIONAL BOARD

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6.2 Disassembly of Control Head

Introduction This subsection covers the disassembly of control heads with UI and the

replacement of a damaged part or assembly. There are two stages in the

disassembly procedure:

■remove control-head board

■replace damaged part or assembly

For the latter task the control-head board must be removed. To repair

the board, removal is unnecessary unless there is a need to gain access to

components on the underside or to replace the complete board. A

separate circuit board for a concealed or dynamic microphone might or

might not be mounted on the control-head board.

Remove Control-head

Board The procedure for removing the control-head board is as follows. Refer

to Figure 6.3.

1. Pull off the knob from the volume-control potentiometer. Do not

use any tools to do so as this might cause damage.

2. If a circuit board for a concealed or dynamic microphone is fitted,

unplug it from the control-head board.

3. If a concealed microphone is fitted, unsolder the microphone leads

from the control-head board. The leads are soldered to pads on

the board as shown in Figure 6.3.

4. Note whether the speaker leads are connected to the control-head

board. If so, disconnect the leads. The radio will need to be

returned to the Customer in its original state.

5. Use a Torx T10 screwdriver to remove the screws securing the

control-head board. The order of removal is immaterial. The

screws are labelled screw 1 to screw 3 in Figure 6.3; these numbers

are also inscribed on the PCB. The control-head board is now

held down only by the clips labelled clip 1 to clip 3 in Figure 6.3.

6. Pull upwards on the edge of the control-head board adjacent to

the speaker. At the same time push clip 1 and clip 2 by hand away

from the board. The board will lift up slightly.

7. Push clip 3 away from the control-head board while

simultaneously pressing on the shaft of the volume-control

potentiometer. The board will be freed from the space-frame.

Remove the board.

8. If the earlier inspections have not revealed any damaged parts,

continue with the repair of the radio as described in

Subsection 5.2 (on page 109). If there is damage, continue with

the disassembly of the control head and rectify the damage as

described below.

132 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Table 6.1 Contents of TMAA22-01 Spares kit 1 and TMAA22-10 Spares kit 10 — parts of the two-

and one-digit-display control heads less the control-head board

IPN Description Quantity Reference

—Front-panel assembly (see below for constituent parts) 1 Figure 2.3

311-01054-xx Knob for volume-control potentiometer 1 Figure 2.3

— Control-head-loom assembly (see below for constituent parts) 1 Figure 2.4

346-10030-08 3 x 8 PT screw for control-head board 3 Figure 2.4

Parts of front-panel assembly

316-06786-xx Front panel 1 Figure 2.3

312-01095-xx Lens with Tait logo (two-digit display) 1 Figure 2.3

312-01106-xx Lens with Tait logo (one-digit display)

365-01717-xx Label for TM8115 1 Figure 2.3

365-01745-xx Label for TM8110

209-00011-xx Elastomeric strip 2 Figure 2.4

319-30073-xx Space-frame 1 Figure 2.4

008-00031-xx LCD 1 Figure 2.5

252-00011-xx Speaker 1 Figure 2.5

307-01024-xx Speaker membrane 1 Figure 2.5

311-03114-xx Keypad 1 Figure 2.5

262-00003-xx Short light pipe 2 Figure 2.5

262-00004-xx Long light pipe 2 Figure 2.5

Parts of control-head-loom assembly

219-02882-xx Control-head loom 1 Figure 2.4

240-00021-41 Female-female adaptor for control-head connector 1 Figure 2.4

Note

The characters xx in an IPN stand for the issue number. Items in the spares kit will always be the latest issue at

the time the spares kit is produced.

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 133

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Front-panel Assembly

and Spares kits 1 and 10 The assembly remaining after the removal of the control-head board is

called the front-panel assembly. A complete front-panel assembly is

included in Spares kit 1 (two-digit display) and Spares kit 10 (one-digit

display). The other parts in these kits are a control-head loom, screws

for the control-head board, and a volume-control knob. The contents

of the kits, including the parts of the front-panel assembly, are listed in

Table 6.1. The IPN of each spare part is given but, if applicable, not the

issue number within the IPN. The latest issue of a particular part is

always supplied.

Repair of Front-

panel Assembly There are two methods of repairing a damaged front-panel assembly:

■replace complete front-panel assembly

■replace damaged parts of front-panel assembly

Generally either method may be used. However, the latter method must

be used if a concealed microphone is fitted or custom labels have been

added to the front panel. The two methods are described separately

below:

Replace Front-panel

Assembly To replace the complete front-panel assembly, discard the damaged

assembly and obtain a replacement assembly from the appropriate spares

kit:

■Spares kit 1 : two-digit-display control head

■Spares kit 10: one-digit-display control head

Leave the spare control-head loom, the screws, and the volume-control

knob in the kit. Continue with the repair of the radio as described in

Subsection 5.2 (on page 109). Later in the repair procedure the control

head board will be fitted to the new front-panel assembly and the

complete control head will be assembled.

134 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.4 Plan view of the control head with the control-head board removed

CLIP 6 CLIP 4 CLIP 2

CLIP 5 CLIP 3 CLIP 1

SPEAKER

LCD

ELASTOMERIC STRIPS

SPACE-FRAME

APERTURE FOR

MICROPHONE

CONNECTOR

KEYPAD

CONCEALED MICROPHONE

(IF FITTED)

APERTURE FOR SHAFT

OF VOLUME-CONTROL

POTENTIOMETER

LIGHT PIPES FOR

STATUS LEDs

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 135

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Replace Damaged Parts

— Disassembly Task To replace a damaged part, first disassemble the damaged front-panel

assembly as well as a spare assembly from the appropriate spares kit.

Proceed as follows. Refer to Figure 6.4.

1. Note the clips on the space-frame labelled clip 1 to clip 6 in

Figure 6.4. These clips need to be released to remove the space-

frame.

2. While pulling upwards on the space-frame at the corner where the

microphone connector is situated, release the clips in the order:

clips 1 and 2, 3 and 4, and then 5 and 6. To release each clip use

a medium-sized (about 5 mm) flat-bladed screwdriver to lever the

clip out of its recess. Pulling on the space-frame helps release the

clips.

3. Pull the space-frame out when all six clips have been released.

4. Remove the elastomeric strips, speaker, LCD, keypad and, if

fitted, concealed microphone.

Replace Damaged Parts

— Replacement Task Replace any of the following parts that external and internal inspection

have shown to be damaged. Refer to the accessories manual regarding

the replacement of a concealed microphone that has been damaged.

■elastomeric strips

■space-frame

■speaker

■keypad

■LCD

■front panel

Obtain replacement parts from the disassembled spare front-panel

assembly. Discard the damaged parts and return unused spare parts to the

spares kit. Note that spare front panels include the speaker membrane,

lens and branding label; the LED light pipes are moulded into the panel.

If any part of the front panel is damaged, including the membrane, lens

and light pipes, replace the complete panel.

136 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.5 Lever points for removing the cover of the radio body

LEVER POINT

UPPER

SCREW

BOSS

DETAILS OF

LEVER POINT

LOWER

SCREW

BOSS

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 137

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6.3 Disassembly of Radio Body

Introduction This subsection covers the disassembly of the radio body. There are three

stages in the disassembly procedure:

■open radio body

■remove main-board assembly

■disassemble main-board assembly

The control head need not be detached before the radio body is opened,

but it must be detached before the main-board assembly can be removed.

Remove the main-board assembly only if it requires repair or

replacement. Disassemble the main-board assembly only if a connector

on the board requires replacement.

Open Radio Body The first stage in disassembling the radio body is to remove the cover and

lid. In the process it is advisable to inspect and, if necessary, replace the

main seal in the lid. The procedure is included in the disassembly

instructions:

1. Note the two screw bosses on each side of the chassis. The cover

clips to the underside of each upper boss. Also note the two points

where the cover should be levered off the radio body. As shown

in Figure 6.5, each lever point is a slot above the lower screw boss.

2. Insert the blade of a small (about 3 mm) flat-bladed screwdriver in

each of the above slots in turn. In each case push the screwdriver

under the cover towards the upper screw boss. This will release

the cover from the upper boss. Remove the cover.

3. Use a Torx T20 screwdriver to remove the four screws securing

the lid of the radio body. The screws are shown in Figure 6.6.

4. Carefully remove the lid. If an options board is fitted, there will

be an options loom connecting the main board in the chassis and

the options board in the lid. If this is the case, place the lid next

to the chassis as shown in Figure 6.7 and disconnect the loom.

5. Inspect the main seal in the lid for any sign of deformation, cuts

or tears. Refer to Figure 6.7. If the seal is damaged, replace it

with a spare seal from Spares kit 2. The contents of the kit are

listed in Table 6.2. The IPN of each spare part is given but, if

applicable, not the issue number within the IPN. The latest issue

of a particular part is always supplied.

6. Continue with the servicing procedure detailed in Subsection 5.2

(on page 109).

138 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.6 The four screws that secure the lid to the chassis of the radio body

CHASSIS

LID

BUNG FOR

AUXILIARY

CONNECTOR

COVER SEAL FOR EXTERNAL

OPTIONS CONNECTOR

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 139

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Figure 6.7 Illustration of the lid removed from the chassis of the radio body, with an options board

installed in the lid

SLOT IN HEAT-TRANSFER

BLOCK FOR SCREWDRIVER

MAIN SEAL

CHASSIS

LID

MAIN BOARD

INTERNAL

OPTIONS

BOARD

MAIN SEAL

OPTIONS LOOM

INTERNAL OPTIONS CONNECTOR

140 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Figure 6.8 Illustration of the chassis showing the screws that secure the main-board assembly

BUNG FOR

AUXILIARY CONNECTOR

SCREW 2 SCREW 3 SCREW 4 SCREW 5

SCREW 1

SCREW 6 SCREW 7

PLAN VIEW

REAR VIEW

PAD TOP

CAN

DIGITAL BOARD

SEAL FOR

RF CONNECTOR

HEAT-TRANSFER BLOCK

MAIN

BOARD

PAF TOP CAN

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Remove Main-board

Assembly The second stage, if necessary, in disassembling the radio body is to

remove the main-board assembly.

1. Remove the bung (if fitted) covering the auxiliary connector.

2. Remove the rubber seal around the RF connector — preferably

by hand. If necessary, however, lever up the seal by inserting the

blade of a small (about 3 mm) flat-bladed screwdriver in the gap

beneath the seal. See Figure 6.8. Do not damage the seal with

the screwdriver.

3. Note the five interior screws securing the main-board assembly;

these are labelled screw 1 to screw 5 in Figure 6.8. Use a Torx

T10 screwdriver to remove the screws. The order of removal is

immaterial, but good practice would be to follow the order from

screw 1 to screw 5.

4. Note the two exterior screws securing the main-board assembly;

these are labelled screw 6 and screw 7 in Figure 6.8. Use a Torx

T20 screwdriver to remove the screws.

5. The main-board assembly is now free of the chassis. Note the slot

in the heat-transfer block shown in Figure 6.7. Insert the blade of

a small (about 3 to 5 mm) flat-bladed screwdriver in the slot. Tilt

the screwdriver to lever up the front edge of the circuit board.

Grip the edge of the board and pull out the assembly, but avoid the

thermal paste on the heat-transfer block and PCB underside. The

areas coated with thermal paste are shown in Figure 2.11 and

Figure 6.9.

142 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Disassemble

Main-board Assembly The third stage, if necessary, in disassembling the radio body is to

disassemble the main-board assembly.

1. Remove the rubber seal for the power connector.

2. Use a torque-driver with a 3/16-inch socket to remove the lock-

nuts for the auxiliary connector.

3. Use a torque-driver with a 14 mm long-reach socket to remove

the hexagonal nut of the RF connector. Also remove the lock

washer.

4. Use a Torx T10 screwdriver to remove the three screws securing

the copper plate on the main board to the heat-transfer block.

Access to the screws is via the holes in the PAD TOP and PAF TOP cans

shown in Figure 6.8.

Figure 6.9 Features of the main-board assembly

AUXILIARY

CONNECTOR

AND SEAL

POWER

CONNECTOR

AND SEAL

HEAT-TRANSFER BLOCK

MAIN BOARD

DIGITAL BOARD

RF CONNECTORTHERMAL PASTE

INTERNAL OPTIONS

CONNECTOR

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 143

May 2004 © Tait Electronics Limited

5. Separate the main board from the heat-transfer block. Avoid

touching or fouling the thermal paste on the copper plate and

heat-transfer block.

6. Replace any faulty connector. In the case of the power connector

note that, as well as the pins being soldered to the PCB, there are

two screws securing the connector. Use a Torx T10 screwdriver

to remove the screws. After replacing the connector, use a torque-

driver to tighten the screws to 0.34 N·m (3 lbf·in).

Table 6.2 Contents of TMAA22-02 Spares kit 2 — mechanical parts of radio body

IPN Description Quantity Reference

—Cover assembly (see below for constituent parts) 1 Figure 2.8

349-02067-xx M4 x 16 screw for lid of radio body 4 Figure 2.8

362-01115-xx Control-head seal 1 Figure 2.8

362-01109-xx Main seal in lid 1 Figure 2.9

302-50000-xx Bung for external options connector 1 Figure 2.9

302-50001-xx Bung for auxiliary connector 1 Figure 2.11

362-01113-xx Seal for RF connector 1 Figure 2.11

349-02067-xx External M4 x 16 screw for main-board assembly 2 Figure 2.11

349-02066-xx Internal M3 x 10 screw for main-board assembly 5 Figure 2.11

362-01114-xx Rubber seal for power connector 1 Figure 2.12

354-01043-xx Lock-nut for auxiliary connector 1 pair Figure 2.12

362-01112-xx Outer foam seal for auxiliary connector 1 Figure 2.12

362-01110-xx Inner foam seal for auxiliary connector 1 Figure 2.12

Parts of cover assembly

303-23166-xx Cover 1 Figure 2.8

365-01712-xx Label for cover 1 Figure 2.8

Note

The characters xx in an IPN stand for the issue number. Items in the spares kit will always be the latest issue at

the time the spares kit is produced.

144 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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6.4 Re-assembly of Radio Body

Introduction There are three stages in the re-assembly of the radio body:

■re-assemble main-board assembly

■install main-board assembly

■close radio body

The first stage is necessary only if the main-board assembly has been

disassembled, and the second only if it has been removed from the chassis.

The procedures for the three stages are given separately below. The

torque values for the fasteners involved are summarised in Table 6.3.

Re-assemble Main-

board Assembly —

Apply Thermal Paste

If the main-board assembly needs to be re-assembled, first replenish the

thermal paste on the copper plate:

1. Thermal paste is required over the complete surface of the copper

plate. The corresponding area of the heat-transfer block is shown

in Figure 2.12. This area constitutes the contact area between the

copper plate and the heat-transfer block.

2. Inspect the area on the copper plate requiring thermal paste, as

well as the corresponding area on the heat-transfer block. If the

residual paste has been contaminated with dirt, clean off the paste.

3. Obtain 0.1 cm3 of thermal paste. Use Dow Corning 340 silicone

heat-sink compound (IPN 937-00000-55) or the equivalent.

4. Use a stiff brush to apply the paste in a thin film to the required

area on the copper plate. Ensure that no bristles from the brush

come loose and remain embedded in the paste. The paste needs

to be completely free of contaminants.

Re-assemble Main-

board Assembly —

Fasten Parts of

Assembly

Complete the assembly of the main-board assembly by securing the main

board to the heat-transfer block.

1. Fit the main board to the heat-transfer block, and screw in the

three screws that secure the copper plate to the heat-transfer block.

Use a Torx T10 torque-driver to tighten the screws to 1.7 N·m

(15 lbf·in).

2. Clean off any excess thermal paste on the heat-transfer block.

3. Secure the two lock-nuts for the auxiliary connector. Use a

torque-driver with a 3/16-inch socket to tighten each lock-nut to

0.90 N·m (8 lbf·in).

4. Fit the lock washer and hexagonal nut of the RF connector. Use

a torque-driver with a 14 mm long-reach socket to tighten the nut

to 1.7 N·m (15 lbf·in).

5. Fit the rubber seal for the power connector. There is only one

correct orientation. Ensure that the seal is properly seated.

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 145

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Install Main-board

Assembly —

Apply Thermal Paste

If the main-board assembly needs to be installed, first replenish the

thermal paste on the heat-transfer block and on the screw boss on the

floor of the chassis:

1. Thermal paste is required on the area of the heat-transfer block

shown in Figure 6.9. This area constitutes the contact area

between the main-board assembly and the chassis.

2. Inspect the area on the heat-transfer block requiring thermal paste,

as well as the corresponding area on the chassis. If the residual

paste has been contaminated with dirt, clean off the paste.

3. Obtain 0.1 cm3 of thermal paste. Use Dow Corning 340 silicone

heat-sink compound (IPN 937-00000-55) or the equivalent.

4. Use a stiff brush to apply the paste in a thin film to the required

area on the heat-transfer block. Ensure that no bristles from the

brush come loose and remain embedded in the paste. The paste

needs to be completely free of contaminants.

5. Thermal paste is also required on the screw boss in contact with

the PCB. The area is shown in Figure 2.11. Inspect the area, as

well as the corresponding area on the PCB. If the residual paste

has been contaminated with dirt, clean off the paste.

6. Replenish the paste on the screw boss as described in Steps 3 and

4. The amount of paste required is about one-tenth of that used

for the heat-transfer block.

Table 6.3 Summary of the torque values for the fasteners used in TM8100 mobile radios

Description of screws Drive type Quantity To rq ue

(N·m)

Torq ue

(lbf·in)

Screws for control-head board Torx T10 3 0.56 5

Screws for lid of radio body Torx T20 4 2.5 22

External screws for main-board assembly Torx T20 2 2.5 22

Internal screws for main-board assembly Torx T10 5 1.9 17

Screws for copper plate Torx T10 3 1.7 15

Screws for power connector Torx T10 2 0.34 3

Lock-nuts for auxiliary connector 3/16-inch socket 2 0.90 8

Hexagonal nut of RF connector Long-reach socket 1 1.7 15

146 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Important Ensure that the two external screws securing the main-

board assembly are properly tightened; otherwise the

radio will overheat and might be damaged.

Install Main-board

Assembly — Secure

Assembly in Chassis

Complete the installation of the main-board assembly by securing the

assembly in the chassis:

1. Place the main-board assembly in position in the chassis.

2. Screw in the two external screws by hand as far as possible. The

screws are labelled screw 6 and screw 7 in Figure 6.8. Ensure that

the screws start easily and are not cross-threaded.

3. Identify the diagonal edge of the PAD TOP can. The can is shown

in Figure 6.8.

4. While pressing down firmly on the diagonal edge of the PAD TOP

can, use a Torx T20 torque-driver to tighten the screws to

2.5 N·m (22 lbf·in). (If the screws are not tightened properly, the

radio will overheat.) The reason for pressing down on the can is

to ensure that the circuit board is seated correctly on the bosses for

the five internal screws.

5. Clean off any excess thermal paste on the heat-transfer block.

6. Screw in the five internal screws by hand as far as possible. The

screws are labelled screw 1 to screw 5 in Figure 6.8. Ensure that

the screws start easily and are not cross-threaded. Then use a Torx

T10 torque-driver to tighten the screws to 1.9 N·m (17 lbf·in).

7. Fit the rubber seal for the RF connector; first fit the upper part of

the seal and then press down around the sides of the seal to the

bottom. Ensure that the seal is properly seated around its entire

periphery.

8. In most radios a bung will have been supplied for the auxiliary

connector. In such cases the bung must be fitted again on re-

assembly to ensure that the radio is sealed. In fitting the bung,

ensure that it is not upside down and that it is properly seated.

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 147

May 2004 © Tait Electronics Limited

Close Radio Body Secure the lid and cover of the radio body as follows:

1. If an options board is installed in the lid of the radio body,

reconnect the options loom to the internal options connector on

the main board. This is best done with the lid placed next to the

chassis as shown in Figure 6.7.

2. Place the lid in position on the chassis. Ensure that the main seal

in the lid is properly seated.

3. Screw in by hand the four screws that secure the lid. Ensure that

the screws start easily and are not cross-threaded. Then use a Torx

T20 torque-driver to tighten the screws to 2.5 N·m (22 lbf·in).

4. Fit the cover of the radio body.

5. Continue with the servicing procedure detailed in Subsection 5.2

(on page 109).

148 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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6.5 Re-assembly and Attachment of Control Head

Introduction There are at most three stages in the re-assembly and attachment of the

control head. The first two stages concern only control heads with UI,

not the blank control head. The three stages are:

■re-assemble front-panel assembly

■re-install control-head board

■re-attach control head

The procedures for the three stages are given separately below. The first

stage is required only if the control head has been completely

disassembled. The second stage is required if the control-head board has

been removed; this stage includes the fitting, if applicable, of the circuit

board for optional concealed and dynamic microphones. The torque

values for the screws involved are included in Table 6.3.

Re-assemble

Front-panel Assembly If the control head has been completely disassembled, re-assemble the

mechanical parts as follows:

1. If the LCD is a spare delivered by TEL and not obtained from

Spares kit 1 or 10, it will have a protective film covering the screen.

Peel off the film before continuing.

2. Ensure that the LCD is free of dirt and fingerprints. Use isopropyl

alcohol and a soft lens-cleaning cloth to clean the LCD, including

the electrical contact points. Take care not to scratch the soft

polariser material on both sides of the LCD.

3. Place the LCD in its recess in the cover as shown in Figure 6.4.

There is only one correct orientation: the small protrusion on the

edge of the LCD must be adjacent to the wall of the front panel.

4. Place the keypad in position on the floor of the front panel.

5. Place the speaker in position and, if included, the concealed

microphone.

6. Place the space-frame in position. Ensure that the leads from the

speaker and, if fitted, the concealed microphone do not foul the

frame. The leads will need to be connected to the top of the

control-head board when the board is installed.

7. Press down on the space-frame until all six clips on the frame snap

into place in their recesses.

8. Ensure that the conductors along the edges of the two elastomeric

strips are clean. Wipe the strips with a soft lens-cleaning cloth. If

necessary, clean the strips using isopropyl alcohol.

9. Insert the two elastomeric strips in their slots in the space-frame.

TM8100 Mobile Radio Service Manual Disassembly and Re-assembly of Radio 149

May 2004 © Tait Electronics Limited

Re-install Control-head

Board Re-install the control-head board and, if included, the optional

microphone board as follows. The torque values for the screws securing

the control-head board are included in Table 6.3.

1. Place the control-head board in position on the space-frame.

Ensure that the board fits inside the four guides on the frame. The

guides are labelled guide 1 to guide 4 in Figure 6.3.

2. Press straight down on the control-head board until the three clips

on the space-frame snap into position against the board. The clips

are labelled clip 1 to clip 3 in Figure 6.3. It is important not to

press down on the circuit board at an angle. To do so might distor t

the elastomeric strips, causing failure in the operation of the LCD.

3. Screw in by hand the three screws that secure the control-head

board. The screws are labelled screw 1 to screw 3 in Figure 6.3.

Ensure that the screws start easily and are not cross-threaded.

Then, beginning with screw 1, use a Torx T10 torque-driver to

tighten the screws to 0.6 N·m (5 lbf·in).

4. If an optional microphone board is included, attach the board to

the control-head board. Two sockets on the former connect to

corresponding plugs on the latter.

5. If a concealed microphone is fitted, solder the leads from the

microphone to the relevant pads on the control-head board. The

pads are shown in Figure 6.3.

6. If the speaker leads were originally connected to the control-head

board, as noted in Subsection 6.2 (on page 131), then reconnect

the leads. Orient the plug on the leads so that the ridge on one

side of the plug is uppermost.

7. Push the knob onto the shaft of the volume-control

potentiometer. Ensure that the knob turns freely.

150 Disassembly and Re-assembly of Radio TM8100 Mobile Radio Service Manual

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Re-attach Control Head Re-attach the control head to the radio body as follows. The procedure

applies both to the blank control head and to control heads with UI.

1. Orient the control head with respect to the radio body as noted in

Subsection 6.1 (on page 127).

2. Reconnect the control-head loom to the connector on the radio

body. Refer to Figure 6.2.

3. Align the control head with the inner face of the radio body.

Ensure that the control-head loom folds properly into the space

between the control head and the radio body.

4. Press the control head against the radio body until it clips into

position. Ensure that the seal is not damaged in the process.

5. Continue with the servicing procedure detailed in Subsection 5.2

(on page 109).

TM8100 Mobile Radio Service Manual Servicing of Control Head 151

May 2004 © Tait Electronics Limited

7 Servicing of Control Head

Scope of Section This section covers servicing of the control head following the initial

investigation described in Subsection 5.2 (on page 109). The

investigation will have revealed either of the following:

■user interface is faulty

■control-head board needs to be replaced

The former includes faults with the two-digit display, LEDs, keys,

speaker, and volume control. Subsection 7.1 to Subsection 7.3 describe

repairs of the user interface. Subsection 7.4 describes the replacement of

the control-head board. Throughout this section data in square brackets

are grid references giving the locations of the components concerned on

the circuit diagram.

Repair of User Interface Faults in the user interface can be divided into two categories:

■faults not involving control-head board

■faults involving control-head board

Subsection 7.1 below and Subsection 7.2 (on page 157) cover the repair

procedures for these two cases respectively. Repair of the control-head

board, however, is a level-2 repair. Level-1 service centres should instead

replace the board as described in Subsection 7.4 (on page 163). For

level-2 service centres, Subsection 7.3 (on page 160) describes how to

find the correct replacement for a faulty component on the board. For

a discussion of SMT repair techniques, refer to Subsection 4.4

(on page 91).

7.1 Faults not Involving Control-head Board

Types of Faults This subsection gives the procedures for rectifying the following faults in

the user interface:

■display is faulty but not LEDs

■some but not all keys are faulty

■speaker is faulty

■volume control is faulty

The repair procedures are given in Tasks 1 to 5 below. A faulty display

might or might not be caused by a faulty control-head board — Tasks 1

and 2 deal with the case where the board is not the cause. The remaining

three faults also do not involve the board, and these are dealt with in

Tasks 3 to 5 respectively.

152 Servicing of Control Head TM8100 Mobile Radio Service Manual

May 2004 © Tait Electronics Limited

Figure 7.1 Primary side of the control-head board

PADS FOR LCDPADS FOR LCD

PADS FOR LCD

PAD FOR KEY

TM8100 Mobile Radio Service Manual Servicing of Control Head 153

May 2004 © Tait Electronics Limited

Tas k 1 —

Display Faulty but not

LEDs — Check

Elastomeric Strips

If all the LEDs function correctly but the display functions only partially

or not at all, first check the elastomeric strips as follows:

1. Disconnect the control-head loom from the control head.

Remove the control-head board as described in Subsection 6.2

(on page 131).

2. Remove the elastomeric strips and check the conductors in the

strips for continuity. Replace the strips if they are faulty. (Obtain

spare strips by disassembling the spare control head of Spares kit 1

or 10 as described in Subsection 6.2.)

3. Ensure that the conductors along the edges of the strips are clean.

Use isopropyl alcohol and a soft lens-cleaning cloth to clean the

edges.

4. Use isopropyl alcohol and a soft lens-cleaning cloth to clean the

pads for the LCD on the control-head board. See Figure 7.1.

5. Insert the elastomeric strips in their slots in the space-frame.

6. Install the control-head board as described in Subsection 6.5

(on page 148).

7. Reconnect the control-head loom to the control head and test the

user interface. If the fault has been removed, return to

Subsection 5.2 (on page 109). If it has not, go to Task 2.

Tas k 2 —

Display Faulty but not

LEDs — Replace LCD

If the elastomeric strips are not the cause of the fault, replace the LCD

as follows:

1. Disconnect the control-head loom. Remove the control-head

board and disassemble the control head as described in

Subsection 6.2.

2. Remove the LCD. Obtain a spare LCD by disassembling the spare

control head of Spares kit 1 or 10 as described in Subsection 6.2.

3. Use isopropyl alcohol and a soft lens-cleaning cloth to clean the

electrical contact points on the spare LCD. Take care not to

scratch the soft polariser material on both sides of the LCD.

4. Re-assemble the control head as described in Subsection 6.5.

5. Reconnect the control-head loom and test the user interface. If

the fault has been removed, return to Subsection 5.2. If it has not,

go to Step 6.

6. The control-head board is suspect. Level-1 service centres should

replace the board as described in Subsection 7.4 (on page 163).

Level-2 service centres should attempt to repair the board as

described in Subsection 7.2 (on page 157).

154 Servicing of Control Head TM8100 Mobile Radio Service Manual

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Figure 7.2 Secondary side of the control-head board with the LCD driver circuitry and other

components indicated

PINS OF RV1

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Tas k 3 —

Some but not All Keys

Faulty

If one or more (but not all) of the keys are faulty, repair the control head

as follows:

1. Disconnect the control-head loom and remove the control-head

board as described in Subsection 6.2 (on page 131).

2. Use isopropyl alcohol and a soft lens-cleaning cloth to clean the

pads on the control-head board for those keys that are faulty.

Figure 7.1.

3. Re-install the control-head board as described in Subsection 6.5

(on page 148).

4. Reconnect the control-head loom and test the keys. If the fault

has been removed, return to Subsection 5.2 (on page 109). If it

has not, go to Step 5.

5. Disassemble the control head completely as described in

Subsection 6.2. Replace the keypad with a spare. Obtain the

spare keypad by disassembling the spare control head of Spares kit

1 or 10 as described in Subsection 6.2.

6. Re-assemble the control head as described in Subsection 6.5.

Reconnect the control-head loom, test the keys to confirm the

removal of the fault, and return to Subsection 5.2.

Tas k 4 —

Speaker Faulty If the speaker functions only intermittently or the audio level is low,

repair the control head as follows:

1. Disconnect the control-head loom and disassemble the control

head completely as described in Subsection 6.2.

2. Replace the speaker with a spare. Obtain a spare speaker by

disassembling the spare control head of Spares kit 1 or 10 as

described in Subsection 6.2.

3. Re-assemble the control head as described in Subsection 6.5.

4. Check the continuity from the speaker connector SK2 to pin 17

(SPK–) and pin 18 (SPK+) [at 1E1] of the control-head connector

SK1 (see Figure 7.2). If there is no fault, go to Step 5. If there is

still a fault, go to Task 5.

5. Reconnect the control-head loom, test the speaker to confirm the

removal of the fault, and return to Subsection 5.2.

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Figure 7.3 Secondary side of the control-head board with IC3, IC5, IC7 and the switching

transistors for the LEDs indicated

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Tas k 5 —

Volume Control Faulty If the volume control works only intermittently, works only at full

volume, or does not work at all, repair the control head as follows:

1. Disconnect the control-head loom.

2. Check that the resistance between pins 1 and 2 of the volume-

control potentiometer RV1 [at 1D3] varies linearly between about

0Ω and 10 kΩ. (see Figure 7.2). If it does, go to Step 3. If it does

not, go to Step 6.

3. Disassemble the control head completely as described in

Subsection 6.2 (on page 131).

4. Replace the speaker with a spare. Obtain a spare speaker by

disassembling the spare control head of Spares kit 1 or 10 as

described in Subsection 6.2.

5. Re-assemble the control head as described in Subsection 6.5

(on page 148). Reconnect the control-head loom. Confirm the

removal of the fault, and return to Subsection 5.2 (on page 109).

6. Remove the control-head board as described in Subsection 6.2.

7. Replace the potentiometer RV1. See Figure 7.1.

8. Re-install the control-head board as described in Subsection 6.5.

Reconnect the control-head loom. Confirm the removal of the

fault, and return to Subsection 5.2.

7.2 Faults Involving Control-head Board

Types of Faults This subsection gives the procedure for repairing a faulty control-head

board. (Level-1 service centres should replace the board as described in

Subsection 7.4 (on page 163), rather than attempt to repair it.) A faulty

board can have the following effects:

■display faulty but not LEDs

■some LEDs faulty

■all LEDs faulty

■display and all LEDs faulty

■all keys faulty

In the case of a faulty display, the cause will have been narrowed to the

board following the checks in Subsection 7.1 (on page 151). The repair

procedures are given below in Tasks 1 to 5 respectively. For obtaining

replacement components, refer to Subsection 7.3 (on page 160).

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Task 1 —

Display Faulty but not

LEDs

If the checks in Subsection 7.1 (on page 151) show that neither the LCD

nor the elastomeric strips are faulty, check the relevant components on

the control-head board as follows:

1. Use an oscilloscope to display the signal at pin 5 [at 1H10] of IC5

(see Figure 7.3). The signal should be a square wave with a

frequency of about 60 Hz and an amplitude that alternates

between 0.0 and 3.3 V. If the signal is correct, go to Step 3. If it

is not, go to Step 2.

2. Replace IC2 [at 1G12] (see Figure 7.3). Test the user interface.

If the fault has been removed, return to Subsection 5.2

(on page 109). If it has not, go to Step 3.

3. Use the oscilloscope to display the signal at pin 12 [at 1H9] of IC7

(see Figure 7.3). The signal should be a square wave with a

frequency of about 120 Hz and an amplitude that alternates

between 0.0 and 3.3 V. If the signal is correct, replace IC5 and go

to Step 4. If it is not, replace IC7 and go to Step 4.

4. Test the user interface. If the fault has been removed, return to

Subsection 5.2. If it has not, the repair failed; replace the control-

head board as described in Subsection 7.4 (on page 163).

Task 2 —

Some LEDs Faulty If the display functions correctly but one or more (but not all) of the

LEDs D1 to D18 are faulty, check the control-head board as follows:

1. Disconnect the control-head loom. Remove the control-head

board as described in Subsection 6.2 (on page 131). Reconnect

the loom to the board.

2. Use a multimeter to measure the forward voltage across each faulty

LED. See Figure 7.1. The voltage should be 2.0 ± 0.4 V DC. If

it is, go to Step 3. If it is not, replace the LED and go to Step 4.

3. If the forward voltage is correct, the LED is functional but the

associated switching transistor is suspect. Replace the transistor

corresponding to the LED in question. The switching transistors

associated with the LEDs D1 to D18 are Q1 to Q4. See

Figure 7.3. Continue with Step 4.

4. Test the user interface. If the fault has been removed, re-install the

control-head board as described in Subsection 6.5 (on page 148),

and return to Subsection 5.2. If it has not, the repair failed;

replace the control-head board as described in Subsection 7.4.

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Tas k 3 —

All LEDs Faulty If the display functions correctly but all the LEDs are faulty, repair the

control head as follows:

1. Disconnect the control-head loom.

2. Replace IC3 [at 1D5] which drives the switching transistors for

the LEDs. See Figure 7.3.

3. Reconnect the loom and test the user interface. If the fault has

been removed, return to Subsection 5.2 (on page 109). If it has

not, the repair failed; replace the control-head board as described

in Subsection 7.4 (on page 163).

Tas k 4 —

Display and All LEDs

Faulty

If the display is faulty as well as all the LEDs, repair the control head as

follows:

1. Use a multimeter to measure the 3.3 V DC supply voltage across

C1 [at 1D2] (see Figure 7.2). If it is correct, go to Step 3. If it is

not, go to Step 2.

2. Check for shorts to ground of the 3.3 V supply. Repair any fault

and go to Step 8.

3. Use the multimeter to check that the RST line at pin 6 [at 1E10] of

IC7 is high. The level should be 3.3 V. If it is, go to Step 5. If it

is not, go to Step 4.

4. Check for continuity in the LCD driver circuitry (D22, C12,

R27) [at 1E9 and 1E10] (see Figure 7.2). Repair any fault and go

to Step 8. If there is no continuity fault, replace IC7 and go to

Step 8.

5. Use the multimeter to check that the OE line at pin 8 [at 1F10] of

IC5 is low. The level should be less than 0.6 V. If it is, replace IC7

and go to Step 8. If it is not, go to Step 6.

6. Check that the voltage at pins 4, 10 and 14 of IC5 is 3.3 V DC.

Also check that pin 7 [at 1J8] of IC5 is at ground. If the voltages

are correct, replace IC7 and go to Step 8. If they are not, go to

Step 7.

7. Check for continuity between IC5 and the control-head

connector SK1. Also check for shorts to ground between IC5 and

SK1. Repair any fault and go to Step 8.

8. Confirm the removal of the fault, and return to Subsection 5.2. If

the repair failed or no fault could be found, replace the control-

head board as described in Subsection 7.4.

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Task 5 —

All Keys Faulty If all the keys, with the exception of the ON/OFF key, are faulty, repair the

control head as follows:

1. Disconnect the control-head loom. Replace IC4 [at 1C2], which

reads the status of the keys. See Figure 7.2.

2. Reconnect the control-head loom and test the keys to confirm the

removal of the fault. If the fault has been removed, return to

Subsection 5.2 (on page 109). If it has not, replace the control-

head board as described in Subsection 7.4 (on page 163).

7.3 Replacement of Faulty Component

Introduction This subsection gives the procedure for obtaining the correct

replacement for any faulty component on the control-head board. There

are four steps:

■identify version of PCB information pack applicable to board

■identify replacement component in BOM of PCB information pack

■consult technical notes

■obtain replacement component

The technical notes will indicate whether there have been any changes

affecting the component in question.

Identify PCB

Information Pack First identify which version of PCB information pack applies to the

control-head board under repair:

1. Note the IPN of the PCB. The IPN is printed at one corner of

the board as shown in Figure 7.1 to Figure 7.3. The last two digits

in the IPN comprise the issue number of the PCB.

2. Compare the issue number in the IPN with that in the PCB

information pack supplied with the service documentation.

3. If the issue numbers match, consult the BOM as described in the

paragraph following the next. If the issue number indicates that

the board is either an earlier or a later version, continue with

Step 4.

4. Obtain the PCB information pack for the board under repair. If

a copy is not available, refer to the Technical Support website as

described in the next paragraph.

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Access Website To locate the correct version of PCB information pack, follow the

procedure given below. It is advisable to print and store a copy of every

PCB information pack published on the Technical Support website.

1. Access the Technical Support website at support.taitworld.com.

2. Click the “Login” button. The Log-in dialogue box appears.

3. Enter the required log-in information in the “Username” and

“Password” fields. (Tait-only access is required.) Click the “Login”

button.

4. Click the “Mobile Radios — TM8000” option. A list of facilities for

this product family appears.

5. Click the “PCB Information” facility. A list of all PCB information

packs for TM8100 radios appears.

6. Navigate to the required PCB information pack and click the

adjacent “view/download” command. The document is displayed.

View the document, print a copy, or save a copy in the test PC.

Alternatively, right-click the “view/download” command and select

the save or print option from the menu that appears.

Identify Replacement

Component After locating the correct PCB information pack for the board, consult

the BOM for the board. Identify the component in question in the

BOM. Note, however, that a new PCB information pack is published

only whenever there is a major change in the design of the board. A

major change normally involves a change in the layout of the PCB,

which requires that the issue number in the IPN be incremented. Any

minor changes following a major change (and preceding the next major

change) normally involve only changes in the components on the board.

Such minor changes might affect the component in question. To

determine if this is the case, consult any technical notes that might apply

to the board; the procedure is given in the next paragraph.

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Consult Technical Notes A technical note about each major change is published on the Technical

Support website. Technical notes giving details of any intervening minor

but important changes are also published. To access these technical

notes, follow the procedure below. It is advisable to print and store a

copy of every technical note published.

1. If not already logged on to the Technical Support website, do so

as described above. (Associate access is sufficient.)

2. Click the “Mobile Radios — TM8000” option. A list of facilities for

this product family appears.

3. Click the “Technical Notes” facility. A list of all technical notes

appears.

4. From the publication dates of the technical notes identify those

that follow publication of the PCB information pack in question.

5. Identify any of the above technical notes that apply to the control-

head board.

6. For each technical note identified in Step 5, click the adjacent

“view/download” command. The technical note is displayed. View

the document, print a copy, or save a copy in the test PC.

Alternatively, right-click the “view/download” command and select

the save or print option from the menu that appears.

7. Determine from the technical notes if any changes apply to the

required replacement component.

Obtain Replacement

Component Determine if the required replacement component is included in Spares

kit 4; a contents list is supplied with the kit. (Check with TEL regarding

the availability of the kit.) If the required component is not included in

the kit, order the component from a CSO or, in the case of a CSO, from

TEL. Always ensure that the replacement component has the identical

specification to that given in the BOM. It is particularly important for

the tolerances to be the same.

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7.4 Replacement of Faulty Control-head Board

Replace Board A faulty control-head board requires replacement in any of these

situations:

■only level-1 repairs permitted

■fault on board not located

■repair of fault failed

If not already done, remove the faulty board as described in

Subsection 6.2 (on page 131). Obtain a spare board from Spares kit 3 or

Spares kit 11. These kits contain replacement control-head boards for

two- and one-digit-display control heads respectively. (Check with TEL

regarding the availability of the kits.)

Re-assemble and

Test Control Head Re-assemble the control head with the replacement control-head board

as described in Subsection 6.5 (on page 148). Reconnect the control-

head loom to the radio body, and test the user interface as described in

Task 5 o f Subsection 5.2 (on page 109). If there is no fault, return to

Subsection 5.2 and continue with the servicing of the radio. If there is

still a fault, the repair failed; remove the spare board, re-assemble the

control head with the original board, and return to Subsection 5.2.

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8 Servicing of Main Board

Scope of Section This section covers servicing of the main board following the initial

investigation described in Subsection 5.2 (on page 109). There are three

aspects:

■fault diagnosis and repair of main board

■replacement of faulty component

■replacement of faulty main-board assembly

These aspects are described in Subsection 8.1 to Subsection 8.3

respectively. The initial investigation will have determined that the main

board is faulty. Subsection 8.1 below gives the subsequent repair

procedure. Repair of the main board, however, is a level-2 repair. Level-

1 service centres should instead replace the complete main-board

assembly as described in Subsection 8.3 (on page 169). For level-2

service centres, Subsection 8.2 (on page 166) describes how to find the

correct replacement for a faulty component on the board.

8.1 Fault Diagnosis and Repair

Identify Suspect

Circuit Module With the information gained from the initial investigation, identify

which module of the circuitry on the main board is faulty:

■power-supply circuitry

■interface circuitry

■frequency synthesizer

■frequency control loop

■receiver

■transmitter

■CODEC and audio circuitry

Depending on which module is suspect, refer to Subsection 9.1 to

Subsection 9.7 respectively for the further fault diagnosis and repair of

the circuit.

Recalibration and

Reprogramming During the above fault-diagnosis procedure, if the calibration is found to

be faulty at any time, recalibrate the radio before continuing. (Certain

restrictions might apply.) Similarly, if there is a problem with the radio

firmware, reprogram the radio before continuing. (Use a default

programming file if necessary.)

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Action Following

Fault Diagnosis There are several outcomes following the fault-diagnosis and repair

procedures given in Section 9 (on page 171). If the main board was

successfully repaired, conclude the servicing task as described below. If

the repair failed, if the fault could not be found, or if the repair required

is a level-3 repair, replace the complete main-board assembly as described

in Subsection 8.3 (on page 169).

Test M ai n-boa rd

Assembly After repairing the main board, confirm the removal of the fault by

carrying out the basic tests given in Subsection 5.2 (on page 109).

Recalibration or reprogramming of the radio, as mentioned above, might

also be necessary. If the tests confirm the removal of the fault, continue

as described in the next paragraph. If they do not, replace the complete

main-board assembly as described in Subsection 8.3.

Re-install Cans

and Retest Finally, re-install all cans on the main board that have been removed; refer

to Subsection 4.4 (on page 91) for information on can replacement.

Repeat the above basic tests following the re-installation of the cans. The

tests should again confirm the removal of the fault. Re-assemble the

radio body as described in Subsection 6.4 (on page 144). Return to

Subsection 5.2 to continue with the servicing of the radio. If the tests

do not confirm the repair, replace the complete main-board assembly as

described in Subsection 8.3.

8.2 Replacement of Faulty Component

Introduction This subsection gives the procedure for obtaining the correct

replacement for any faulty component on the main board. There are

four steps:

■identify version of PCB information pack applicable to board

■identify replacement component in BOM of PCB information pack

■consult technical notes

■obtain replacement component

The technical notes will indicate whether there have been any changes

affecting the component in question.

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Identify PCB

Information Pack First identify which version of PCB information pack applies to the main

board under repair:

1. Note the IPN of the PCB. The IPN is the ten-digit number

printed at one corner of the board. The last two digits in the IPN

comprise the issue number of the PCB.

2. Compare the issue number in the IPN with that in the PCB

information pack supplied with the service documentation.

3. If the issue numbers match, consult the BOM as described in the

paragraph following the next. If the issue number indicates that

the board is either an earlier or a later version, continue with

Step 4.

4. Obtain the PCB information pack for the board under repair. If

a copy is not available, refer to the Technical Support website as

described in the next paragraph.

Access Website To locate the correct version of PCB information pack, follow the

procedure given below. It is advisable to print and store a copy of every

PCB information pack published on the Technical Support website.

1. Access the Technical Support website at support.taitworld.com.

2. Click the “Login” button. The Log-in dialogue box appears.

3. Enter the required log-in information in the “Username” and

“Password” fields. (Tait-only access is required.) Click the “Login”

button.

4. Click the “Mobile Radios — TM8000” option. A list of facilities for

this product family appears.

5. Click the “PCB Information” facility. A list of all PCB information

packs for TM8100 radios appears.

6. Navigate to the required PCB information pack and click the

adjacent “view/download” command. The document is displayed.

View the document, print a copy, or save a copy in the test PC.

Alternatively, right-click the “view/download” command and select

the save or print option from the menu that appears.

168 Servicing of Main Board TM8100 Mobile Radio Service Manual