Huawei Release Notes F Tanjim Qmobile Call Centre Singer Y200 U8655 1. 51053288 U8655N(MTC965) Maintenance Manual V1.0

2014-08-11

User Manual: Huawei

Open the PDF directly: View PDF .
Page Count: 72

Download
Open PDF In Browser	View PDF

U8655N

Maintenance Manual

Issue

1.0

Date

2012-09-27

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2012. All rights reserved.
No part of this document may be reproduced or transmitted in any form or by any means without prior
written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions
and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd.
All other trademarks and trade names mentioned in this document are the property of their respective
holders.

Notice
The purchased products, services and features are stipulated by the contract made between Huawei and
the customer. All or part of the products, services and features described in this document may not be
within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements,
information, and recommendations in this document are provided "AS IS" without warranties, guarantees or
representations of any kind, either express or implied.
The information in this document is subject to change without notice. Every effort has been made in the
preparation of this document to ensure accuracy of the contents, but all statements, information, and
recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd.
Address:

Huawei Industrial Base
Bantian, Longgang
Shenzhen 518129
People's Republic of China

Website:

http://www.huawei.com

Email:

support@huawei.com

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

About This Document

About This Document
Purpose
Prepared by

R&D

Date

Reviewed by

Maintenance support team

Date

Approved by

Service representative

Date

Change History
Date

Version

Change Reason

2012-02-20

V1.0

Released the first issue.

Issue 1.0 (2012-02-23)

Revised Section

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

Description

Author
R&D

U8655
Maintenance Manual

Contents

Contents
About This Document .................................................................................................................... ii
1 Product Introduction .................................................................................................................... 1
1.1 Appearance ....................................................................................................................................................... 1
1.2 Specifications ................................................................................................................................................... 1

2 Applicable Scope and Precautions ............................................................................................ 3
2.1 Applicable Scope .............................................................................................................................................. 3
2.2 Precautions ....................................................................................................................................................... 3
2.3 How to Obtain Product and Repair Information .............................................................................................. 3

3 Exploded View............................................................................................................................... 4
4 Components on the PCBA ........................................................................................................... 6
5 Software Upgrade ......................................................................................................................... 8
5.1 Upgrade Preparation......................................................................................................................................... 8
5.2 Upgrade Procedure ........................................................................................................................................... 8

6 Maintenance Tools ...................................................................................................................... 10
7 Disassembly Procedure .............................................................................................................. 12
8 Assembly Procedure ................................................................................................................... 17
9 Principles and Failure Analysis ............................................................................................... 21
9.1 Block Diagram ............................................................................................................................................... 21
9.1.1 Function Description of the PCBA ....................................................................................................... 22
9.2 Baseband Unit ................................................................................................................................................ 25
9.2.1 Power-on Management Circuits ............................................................................................................ 25
9.2.2 Charging Management Circuits ............................................................................................................ 29
9.3 RF Unit ........................................................................................................................................................... 30
9.3.1 RF Failure ............................................................................................................................................. 30
9.3.2 GPS ....................................................................................................................................................... 33
9.3.3 Wi-Fi/Bluetooth/FM Module ................................................................................................................ 33
9.4 Peripheral Circuits .......................................................................................................................................... 34
9.4.1 Display .................................................................................................................................................. 34
9.4.2 Camera .................................................................................................................................................. 37

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

iii

U8655
Maintenance Manual

Contents

9.4.3 USB....................................................................................................................................................... 39
9.4.4 Headset Jack.......................................................................................................................................... 40
9.4.5 Keys ...................................................................................................................................................... 42
9.4.6 Status Indicator and Touch Key Backlight Circuits .............................................................................. 43
9.4.7 Battery Connector ................................................................................................................................. 44
9.4.8 Accelerometer ....................................................................................................................................... 45
9.4.9 Proximity and Illuminance Sensor ........................................................................................................ 45
9.4.10 Vibration Motor................................................................................................................................... 47
9.4.11 Receiver .............................................................................................................................................. 48
9.4.12 Microphone ......................................................................................................................................... 50
9.4.13 Touchscreen Panel ............................................................................................................................... 51
9.4.14 SIM Card............................................................................................................................................. 52
9.4.15 microSD Card ..................................................................................................................................... 53
9.4.16 NFC ..................................................................................................................................................... 54

10 Solder Points on the PCB and BGA Chip............................................................................. 59
11 Functional Tests......................................................................................................................... 64
11.1 MMI Test ...................................................................................................................................................... 64
11.2 Voice Call Test .............................................................................................................................................. 67

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

1 Product Introduction

Product Introduction

1.1 Appearance

1.2 Specifications
Category

Description

Dimensions (H x W x D)

116.9 mm x 61.4 mm x 12.2 mm

Technical standard

U8655N: W2100/W900, GSM850/900/1800/1900

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

1 Product Introduction

Category

Description

Frequency bands

U8655N:


WCDMA 900MHz: 880–915 MHz (UL), 925–960 MHz (DL))



WCDMA 2100 MHz: 1920–1980 MHz (UL), 2110–2170 MHz (DL)



GSM 850 MHz: 824–849 MHz (UL), 869–894 MHz (DL)



GSM 900 MHz: 880–915 MHz (UL), 925–960 MHz (DL)



GSM 1800 MHz: 1710–1785 MHz (UL), 1805–1880 MHz (DL)



GSM 1900 MHz: 1850–1910 MHz (UL), 1930–1990 MHz (DL)

Weight

< 125 g with battery

Form factor

Bar

Antenna

Built-in

UIM

SIM, USIM

Charger

5 V, 1000 mA

Battery

Type: Li-ion
Capacity: 1250 mAh
Standby time: 220–250 hours (network dependent)
Talk time: 210 minutes (network dependent)

Display

Connectors

Resolution

320 x 480 pixels

Type

TFT LCD

Color

262K

Size

3.5 inches

Charging port

micro-USB connector

USB port

micro-USB connector

microSD card
interface

microSD card interface

Headset jack

3.5 mm (LRGM)

Maximum
transmission
power

23–33 dBm

Static
sensitivity

≤ 104 dBm

Temperature

Operating temperature: 0°C to +40°C
Storage temperature: –20°C to +50°C

Humidity

Operating humidity: 5% to 95% RH

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

2 Applicable Scope and Precautions

Applicable Scope and Precautions

2.1 Applicable Scope
This document provides repair instructions for technicians at service centers authorized by
Huawei. This maintenance manual is confidential and accessible to authorized service centers
(ASCs) and authorized service providers (ASPs) only. While every effort has been made to
ensure the accuracy of this document, errors may still exist. If you find any errors or have any
suggestions, please contact Huawei’s customer service.

2.2 Precautions


Only qualified technicians are allowed to perform repair and calibration.



Perform all operations in electrostatic discharge (ESD) rooms and wear ESD wrist straps
throughout the operations.



Ensure that all components, screws and insulators are properly installed after repair and
calibration, and that all cables and wires are installed and connected correctly.



Ensure that the soldering is lead-free and compliant with eco-friendly requirements.
ESD is the main cause of damage to electrostatic-sensitive components. Each
ASC must exercise caution to avoid ESD damage and comply with the ESD
protection requirements in this manual.

2.3 How to Obtain Product and Repair Information
To obtain description and repair information about Huawei's products, please visit
http://www.huaweidevice.com/worldwide/technicaIndex.do.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

3 Exploded View

Exploded View

The components listed in the following table are structural parts of the phone, and cannot be
used as reference when requesting spare parts.

1
5

Table 3-1 List of components in the exploded view drawing
No.

Item

Quantity

U8655N_Cover A assembly

Touchscreen panel

U8655N_Cover B assembly

U8655N_Battery cover assembly

U8655N_Volume key

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

3 Exploded View

No.

Item

Quantity

U8655N_Speaker shielding cover

U8655N_CPU shielding cover

U8655N_RTR shielding cover

U8655N_PA shielding cover

U8655N_Proximity and illuminance sensor sealing sheath

U8655N_MIC_sheath

U8655N_LCD_conductive fabric

U8655N_Headset insulation film

U8655N_USB_adhesive film

Screw M1.4*3.5

Diversity antenna and Wi-Fi antenna

Bluetooth antenna

Main antenna

LCD

Power key flexible flat cable (FFC)

Receiver

PCBA

Volume key FFC

Camera

Speaker

Battery

NFC antenna

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

4 Components on the PCBA

4
J1001camera connector
Failure of this component
can cause:
Camera shooting failure.

Components on the PCBA

J1101 headset jack
Failure of this component
can cause:
Headset failure.

J1601 BTB connector
Failure of this component
can cause:
Touchscreen panel failure.

J11302 BTB connector
Failure of this component
can cause:
Display failure.

U4101 GPS LNA
Failure of this component
can cause:
GPS failure.

U1402 SD card filter
Failure of this component
can cause:
SD card failure.

J1401 SIM card holder
Failure of this component
can cause:
SIM card failure.

U1303 voltage regulator
Failure of this component
can cause:
LCD backlight failure.

J1402 SD card holder
Failure of this component
can cause:
SD card failure.

U6000 Wi-Fi/Bluetooth/FM
3-in-1 chip
Failure of this component
can cause:
WiFi, Bluetooth and FM
failure.

U601 Flash memory chip
Failure of this component
can cause:
Power-on failure, software
are malfunction.

U201 power management
chip, PM8029
Failure of this component
can cause:
Power-on failure.

U401 CPU, MSM7225A
Failure of this component
can cause:
Power-on failure, phone
system crash, RF failure.

X301 crystal oscillator
32.768KHz
Failure of this component
can cause:
Power-on failure.

U4401 NFC module
Failure of this component
can cause:
NFC function failure.

J1605 ZIF connector
Failure of this component
can cause:
Volume key failure.

U3302 power module, PA
Failure of this component
can cause:
W2100MHz transmission
failure.

U1204 accelerator
Failure of this component
can cause:
Accelerator failure.

U902 motor
Failure of this component
can cause:
Vibration failure.
U3304 duplexer
Failure of this component
can cause:
W2100MHz transmission
and reception failure.

Issue 1.0 (2012-02-23)

J902 battery connector
Failure of this component
can cause:
Power-on failure.
U3202 RF switch
Failure of this component
can cause:
RF failure.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U3201 RF connector
Failure of this component
can cause:
RF failure.

U8655
Maintenance Manual

4 Components on the PCBA

U1207 proximity and
illuminance sensor
Failure of this component
can cause:
Proximity and illuminance
detection failure.

D1200 tricolor indicator
Failure of this component
can cause:
Tricolor indicator failure.

U3401 power module, PA
Failure of this component
can cause:
W900MHz transmission
failure.
U3404 duplexer
Failure of this component
can cause:
W900MHz transmission
and reception failure.

U3501 power module, PA
Failure of this component
can cause:
GSM transmission failure.

Issue 1.0 (2012-02-23)

U901 DCDC control chip
Failure of this component
can cause:
Charging failure.

F901 fuse
Failure of this component
can cause:
Charging failure.

J901 IO connector
Failure of this component
can cause:
Charging failure.
data communication failure.

U3801 WCDMA/GSM
transmission and
reception chip
Failure of this component
can cause:
RF failure.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

5 Software Upgrade

Software Upgrade

5.1 Upgrade Preparation
Category

Item

Description

Upgrade
environment

Computer

To copy upgrade software

microSD card

With more than 512 MB free space

Battery

With at least 30% power remaining

Main upgrade pack

dload/UPDATE.APP

Vendor upgrade pack

vendor_XXX_XXX/UPDATE.APP

Using the microSD card

Normal upgrade

Upgrade file

Upgrade
method

Forcible upgrade

5.2 Upgrade Procedure
1.

Format the microSD card.

Create a folder named dload in the root directory of the microSD card.

Copy the upgrade file to the dload folder.

Install the microSD card on the phone. Power the phone on, and enter *#*#2846579#*#*
on the idle screen.

Select SD Upgrade then Yes to start the upgrade.

Before the upgrade, NV items backup is performed (if the phone's NV items has not
been backed up before). Then the phone restarts and the upgrade starts.

The upgrade progress is displayed on the LCD.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

5 Software Upgrade

After the upgrade is completed, the phone restarts and the NV items are restored.

After the main upgrade pack is upgraded, upgrade the vendor upgrade pack using the
same upgrade method.

If the phone cannot be properly powered on, use one of the following two methods to forcibly
upgrade the phone:


Install the battery on the phone (if the screen is jittering, remove the battery and wait for
five seconds before installing the battery again). Press and hold the Volume+ and
Volume– keys, and press the Power key. The phone enters the SD forcible upgrade mode
in which the upgrade process is similar to the normal upgrade.



While the phone has no battery installed, press and hold the Volume+ and Volume– keys,
and connect the charger to the phone.
The phone enters the SD forcible upgrade. This method is recommended. If the forcible
upgrade still fails, use another microSD card and try forcible upgrade again.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

6 Maintenance Tools

Maintenance Tools

Name: constant-temperature hot air blower gun
Usage: to heat components

Name: constant-temperature heat gun
Usage: to heat components

Name: soldering iron
Usage: to solder components

Name: DC regulated power supply
Usage: to supply DC power

Name: soldering table
Usage: to secure the main PCBA

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

6 Maintenance Tools

Name: lead-free solder wire
Usage: soldering

Name: digital multimeter
Usage: to measure during repair

Name: toolkit
Usage: to assemble and disassemble components

Name: electric screwdriver
Usage: to fasten and remove screws

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

7 Disassembly Procedure

Disassembly Procedure

U8655N before disassembly

1. Wear an ESD wrist strap, and ensure that the strap is
grounded properly.

2. Remove the battery cover: Press the upper part of
the battery cover and push it towards the bottom.

Issue 1.0 (2012-02-23)

3. Remove the battery.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

7 Disassembly Procedure

4. Remove the six screws from cover B.

5. Use the disassembly tab to release the latch in the
upper right corner.

6. Use the disassembly tab to release the latch in the
upper left corner.

7. Use a cover opener to release the latches between
cover A and cover B.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

7 Disassembly Procedure

8. Remove the volume key.

9. Release the volume key FPC.

10. Disconnect the BTB connector cable between the
touchscreen panel and the LCD.

11. Release the two latches in the PCBA.

12. Remove the PCBA.

13. Remove the proximity and illuminance sensor
sheath and the microphone sheath.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

7 Disassembly Procedure

14. Release the BTB connector, and remove the
camera. Release the ZIF connector, and remove the
volume key FPC.

16. Apply a protective film on the LCD.

Issue 1.0 (2012-02-23)

15. Release the LCD latches, and remove the LCD.

17. Apply a protective film on the inner side of the
touchscreen panel.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

7 Disassembly Procedure

18. Remove the Power key FPC.

19. Remove the receiver.

20. Remove the speaker.

21. The phone is now disassembled.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

8 Assembly Procedure

U8655N before assembly

Assembly Procedure

1. Wear an ESD wrist strap, and ensure that the strap is
grounded properly.

2. Install the camera on the PCBA, and snap the BTB
connector in place. Install the volume key FPC into the 3. Install the receiver.
ZIF connector, and attach the adhesive film.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

8 Assembly Procedure

4. Install the Power key FPC.

5. Remove the protective film from the touchscreen
panel.

6. Remove the protective film from the LCD.

7. Install the LCD. Ensure that the two latches are
snapped in place and that the LCD is even.

8. Install the PCBA: Insert the USB port into cover A,
and then snap the PCBA downward in place.

9. Gently press the PCBA to close the latches to secure
the PCBA.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

8 Assembly Procedure

10. Snap the LCD's BTB connector and then the
touchscreen panel's BTB connector in place.

11. Install the volume key: Attach the volume key FPC
to the metal piece on cover A, and then install the
volume key.

12. Install the speaker.

13. Install cover B: Snap cover B's bottom, and press
its top.

14. Install the six screws into cover B.

15. Install the battery: Insert it into the battery
compartment bottom first.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

8 Assembly Procedure

17. The phone is now assembled.
16. Install the battery cover.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Principles and Failure Analysis

9.1 Block Diagram

The MSM7X2XA (the U8655N uses the MSM7225A) is the baseband signal processing chip,
mainly responsible for processing the input and output of IMGE, VIDEO, AUDIO, MEMEO
SUPPORT, RF INTERFACES, and CONECTIVITY signals. The baseband chip provides
keypad, LCD, SD card, Wi-Fi, Bluetooth, camera, and microphone interfaces.
The PM8029 is mainly responsible for:
Detecting the connection and disconnection of the external power supply.
Supplying power to the phone.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Providing analog multi-channel switch, real-time clock circuit, TCXO clock circuit, motor
driver circuit, and speaker driver circuit.
The RTR6285A is the RF signal processing chip, responsible for converting UMTS/GSM
uplink/downlink RF signals and using I/Q signals to exchange data with the baseband chip.

9.1.1 Function Description of the PCBA
The PCBA can be divided into four sub-systems: baseband, RF, power supply, and user
interfaces. The following table describes the subsystems' modules and units, as well as their
functions.
Table 9-1 PCBA subsystems' modules, units, and functions
Subsystem

Module

Unit

Function

Baseband
subsystem

MSM7225A

Modem subsystem

The modem subsystem includes the ARM11
processor, modem DSP, modem AHB bus,
interruption controller, and sleep controller.
The ARM9 is a 400 MHz modem processor,
responsible for modulation and demodulation of
WCDMA, GPS, and GSM signals.

Application
subsystem

The subsystem includes ARM A5 processor,
application DSP, and dedicated data mover.
The A5 processor has a clock rate of 800 MHz,
supporting function modules such as the microSD
card, EBI2, UART/USIM, I2C, GPIO, and clock
modules.

User interface
processing unit

Provides camera, PCM, broadband codec, vocoder,
RF, HKADC, LCD, SD card, USB, UART, USIM
card, SBI, GPIO, JTAG/ETM, and keypad
interfaces.

Multimedia and
game engine

The multimedia and game engine is an MPEG/JPEG
hardware engine providing Java acceleration and
MP3/MMS/MIDI/VR processing functions.

Power supply voltage
monitoring

Lists objects being monitored, such as the external
power supply input, Li-ion battery, and charger.

Temperature
monitoring

Monitors the battery temperature.

NAND flash
memory

File system support

Stores applications and NV items. Capacity: 4 GB.

DDR1 RAM

Random access
memory

Provide storage space for running applications.
Capacity: 2 GB.

WCDMA, and
GSM/DCS
signal
transmission and
reception

AFC circuit, APC
circuit, AGC circuit

Performs the RF function of WCDMA signal
reception and transmission.

PM8029

RF
subsystem

Issue 1.0 (2012-02-23)

Mainly includes the RTR6285A RF chip and the
peripheral circuit.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

Subsystem

9 Principles and Failure Analysis

Module

Unit

Function

GPS

GPS reception

Receives and processes GPS signals.
Mainly includes the RTR6285A chip and the
peripheral circuit.

Bluetooth
interface

Bluetooth/Wi-Fi/FM
3-in-1 module

Performs baseband functions for Bluetooth, Wi-Fi
and FM signals.
Transmits and receives Bluetooth, Wi-Fi and FM
signals.
Mainly includes the Bluetooth/Wi-Fi/FM module
and its peripheral circuit.

Wi-Fi interface

Same as the
Bluetooth interface

Same as the Bluetooth interface

Oscillator and
frequency
synthesizer

Crystal oscillators

Generates highly accurate VCTCXO frequency for
the 19.2 MHz local reference clock. The RTR6285A
has a built-in local oscillator (LO) providing clock
frequency for transmitting and receiving WCDMA
and GPS signals.

Antenna

External antenna,
internal interface
component, antenna
protection

The phone uses internal antennas for wireless
communication, supporting WCDMA high and low
frequency bands.

Power coupler

Couples part of the power output from the WCDMA
power amplifier to the RTR6285A for power
monitoring.

Coupler

User
interface
subsystem

MSM7225A subsystem's UART1 interface for
Bluetooth.

UART interface
USB interface

The antennas are the main antenna, GPS antenna,
diversity antenna, Wi-Fi/Bluetooth antenna, FM
antenna (headset) and NFC antenna.

Driver, protection
circuit, output
interface component

The peripheral circuit, protection circuit and
interface connectors of the USB interface in the
MSM7225A subsystem.
It is the major data service channel for the
engineering sample, and can be used to debug and
test devices during R&D.

USIM card
interface

Power supply,
protection circuit,
USIM card holder

Mainly includes the USIM card holder and related
connection circuits.

Keypad and
backlight

Keypad driver
circuit, external
keypad, backlight
LED control circuit

Supports GPIO for keypad scanning.

Color LCD and
backlight

LCD driver, interface
mode, and backlight
control

The phone's LCD with 256K colors. The brightness
of the LCD backlight can be adjusted by users.

Issue 1.0 (2012-02-23)

Provides backlight LED. When a key is pressed, the
backlight is on.
Works in conjunction with PM8029 to provide the
keypad backlight brightness adjustment function.

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

Subsystem

Power
supply
subsystem

9 Principles and Failure Analysis

Module

Unit

Function

Speaker

Driver mode,
connection mode,
speaker component

Plays polyphonic ringtones for incoming calls.

Receiver

Driver mode,
connection mode,
receiver component

Emits sound during a call.

Microphone

Interface circuit,
connection mode,
microphone
component

The phone has two built-in microphones to
eliminate the environmental noise.

Earphone

Earphone, headset
interface circuit,
microphone interface
circuit

The phone provides a headset jack to output music
playback audio or voice during a call. The
microphone on the headset cable can pick sound and
input it into the phone. TheU8655N supports only
the LRGM headsets.

Vibration motor
interface

Driver mode,
connection mode,
motor

When there is an incoming call, the motor can
vibrate notify the user of the call.

NFC

I2C interface control

Performs proximity sensing function.

Proximity and
illuminance
sensor

I2C interface control

Senses the intensity of environmental light for
adjusting the LCD and keypad backlight brightness.

Accelerometer

I2C interface control

Senses acceleration to help implement game
functions.

Battery

Li-ion battery

3.7 V/1250 mAh (the battery must be certified and
comply with relevant safety regulations).

External power
supply (travel
charger)

Adapter, and
interface component

The charger meets the requirements of China,
Europe, the USA, and Australia.

The maximum power of the speaker is 500 mW.
It has good frequency response for playing
20–20000 Hz ringtones. It can also play
monophonic MP3 audio files.

Detects the distance between the phone and the
user's skin and turns the LCD and touchscreen panel
off when the distance is smaller than the specified
value.

Charger specifications: 90–240 V, 45–55 Hz, AC
input. The model differs with different markets.
The output voltage of the charger is 5±0.25 V.The
charger must be CE and CCC certified.
The charger's output current must be able to charge
the battery and supply power to the phone for
normal operation at the same time.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

Subsystem

9 Principles and Failure Analysis

Module

Unit

Function

Power
distribution
network and
power
management
function

Power distribution
network

Includes filter networks and PCB traces for the
power supply.

PM8029
enhanced
function

Battery management,
charging circuit,
charging mode, and
charging protection

Manages battery charging and discharging, provides
overcharging and over-discharging protection, and
charges the capacitor that supplies power to
maintain the real-time clock (RTC).

Board circuit power
management
(power-on/off
analysis)

Mainly controls the low-dropout (LDO) regulator
power supply to flexibly manage power supply.

RTC

The built-in RTC circuit uses a sleep clock of
32.768 kHz to provide precise time.

HKADC

Contains 8 MPP interfaces. Analog-to-digital
conversion can be implemented inside the PM8029.

TCXO driver

The PM8029 has a built-in TCXO driver providing
two analog signal output channels and two digital
signal output channels.

UVLO

Provides the Undervoltage-Lockout (UVLO)
function. When the input voltage is lower than the
threshold for a specific period of time, the phone
powers off.

Over temperature
protection

When the on-chip junction temperature exceeds
150°C, the phone powers off.

Internal driver circuit

Provides one vibration motor driver and one speaker
driver.

Interrupt
management

The built-in interrupt manager handles related
interrupt signals.

USB driver

Supports USB 2.0; does not support USB OTG.

Based on the service status and the requirements of
the interface power supply specifications and
power-saving analysis, the board software manages
the power supplies to the units on the board to
reduce power consumption.

9.2 Baseband Unit
9.2.1 Power-on Management Circuits
On the U8655N, most power supplies are provided by the power management chip PM8029.
Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

The PM8029 provides two types (switched-mode power supply and LDO regulators) of
programmable voltage regulators with a total of 24 output channels.
The follow table lists the voltage regulator parameters.
Table 9-2 Voltage regulator specifications

Troubleshooting Process
To troubleshoot the power-on failure, firstly check whether the I/O connector (battery
connector) is damaged. If the I/O connector (battery connector) is not damaged, use a DC
regulated power supply to supply power to the phone, and test the phone's current.
The power-on failure may be caused by any of the following conditions:


Issue 1.0 (2012-02-23)

No current

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Power-on failure:
no current

Is the battery
connector J902
normal?

Replace J902

Is Q201 normal?

Replace Q201

Y
Re-solder or replace
U201



Issue 1.0 (2012-02-23)

Weak current

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis
Powe-on failure:
weak current

Reinstall the phone's
firmware. Is the problem
solved

End

Is U201'output
Voltage normal

Replace U201

Does X301 have
32.768 kHz output?

Replace X301

Replace U601 and reinstall
The phone's firmware. Is the
Problem solved?

End

Replace U401



Excessive current

Excessive current is caused by short circuits. When excessive current occurs, to prevent
damage to components, do not connect the charger to the phone. Power-on failure due to
excessive current is usually the result of short-circuited VBAT circuit.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis
Powe-on failure:
excessive current

Test the VBAT circuit.Is it
a short circuit

Check whether
VPH_PWR and
PM output are
short-circuited

Is J902 normal?

Re-solder or
replace J902

Is Q201 normal?

Replacec Q201

Replace U201

Remove U201.Do short
circuits still exist?

Replace U401

9.2.2 Charging Management Circuits

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting Charging Failure
Charging failure

Is the charger working
properly?

Replace the
charger

Re-solder J901

Is J901 poorly
soldered?

Is the battery's in good
contact with the battery
connector?

Repair or replace
J902

Does VPH_PWR have
voltage?

Replace U901

Y
Is there voltage difference
between Q201's pin 2 and
pin 3?

Replace Q201

Replace the
battery

Is the battery damaged?

N
End

9.3 RF Unit
9.3.1 RF Failure
Troubleshooting Transmission Failure


GSM/DCS transmission failure

Before starting the following process, make sure that the USIM card and the antenna are well
connected.
Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

GSM/DCS transmission
f ailure

N
When the RF cable is not
inserted, are U3201's pin
1 and pin 2 connected?

Check U3201

N
Are U3202's control signals
normal?

Check U3202 and
U401

Y
N
Are U3501's GSM output
and DCS output
approximately 33 dBm and
30 dBm respectively?
Y

Check U3501

Do U3801's
pin A10 and pin
Y
A9 have output?

Check U3801

Y
Check U401

NOTE


The following tables describe the working status of the GSM/DCS power amplifier U3501.

GSM_PA_EN

OFF

GSM_PA_BAND

MODE

GSM850/900

DCS1800/1900



H: voltage higher than 1.3 V. L: voltage lower than 0.5 V.



WCDMA transmission failure (use W2100 as an example)

Before starting the following process, make sure that the USIM card and the antenna are well
connected.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

W2100 transmission
failure

N
When the RF cable is not
inserted, are U3201's pin 1
and pin 2 connected?

Check U3201

N
Are U3202's control signals
normal?

Check U3202 and
U401

Y
N
Is the insertion loss
between U3304's pin 1 and
pin 3 approximately 1.1–1.4
dB?

Check U3304

Is the insertion loss
Y U3302's pin 2 and
between

Check U3302

pin 9 approximately 0.6 dB?

N
Check U3301

Is U3301's output 24 dB?
Y
Y

N
Does U3801's pin A7 have
output?

Check U3801

Check U401

NOTE


The following tables describe the working status of the WCDMA power amplifier.

PA_ON

OFF

PA_R

PA_R1

MODE

HI Power

MI Power

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis



LO Power

H: 1.3–1.8 V. L: < 0.5 V.

9.3.2 GPS
The GPS channel consists of filter U4102, filter U4103 and LNA U4101. GPS signals are sent
to the RTR6285A's input interface after going through the filters and LNA. The following
figure shows the circuit.

9.3.3 Wi-Fi/Bluetooth/FM Module
The U8655N uses a Wi-Fi/Bluetooth/FM 3-in-1 module (Broadcom's BCM4330).
The Bluetooth and Wi-Fi functions share one antenna and one SP3T RF switch.
The MSM7225A provides PCM and UART interfaces that are directly connected with the
Bluetooth module's PCM and UART signal output. The following table describes the signals'
definitions.
MSM7225A

Signal

Definition

GPIO_44

UART1_CTS_N

The "ready to receive" signal from the
host (the MSM7225A) to the slave (the
BCM4330).

GPIO_43

UART1_RFR_N

The "clear to send" signal sent from the
slave to the host.

GPIO_46

UART1_TX

Transmission signal

GPIO_45

UART1_RX

Reception signal

GPIO_69

AUX_PCM_DIN

PCM input

GPIO_68

AUX_PCM_DOUT

PCM output

GPIO_70

AUX_PCM_SYNC

PCM synchronization

GPIO_71

AUX_PCM_CLK

PCM clock

GPIO_107

MSM_WAKES_BT

Waking up the host

GPIO_83

BT_WAKES_MSM

Waking up the Bluetooth

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

The MSM7225A provides SDIO3 interfaces that are directly connected with the Wi-Fi
module's SDIO signal output. The following table describes the signals' definitions.
MSM7225A

Signal

Function

GPIO_64

SDC2_DATA3

Data

GPIO_65

SDC2_DATA2

GPIO_66

SDC2_DATA1

GPIO_67

SDC2_DATA0

GPIO_62

SDC2_CLK

Clock

GPIO_63

SDC2_CMD

Control signal

The PM8029 provides audio input interfaces that are directly connected with the FM module's
left and right channels. The following table describes the signals' definitions.
BCM4330

Network

MSM7225A

Description

FM_RXP

FM_ANT

FM_RXN

FM_VDD2P5

SR_AVDD2P5

FM_AOUT1

FM_OUT_L

PM8029
LINE_IN_LP

FM OUTPUT

FM_AOUT2

FM_OUT_R

PM8029
LINE_IN_RM

FM OUTPUT

FM antenna (headset)
-

9.4 Peripheral Circuits
9.4.1 Display
The MSM7225A uses MIPI interfaces to send instructions and data to the LCD. The
U8655N's LCD uses MIPI interfaces, supporting a 60 Hz refresh rate, and requiring only one
pair of differential clock signals and one pair of differential signals. The LCD also supports
frame synchronization, using the MDP_VSYNC signals (GPIO_097) as data transmission
synchronization signals to avoid screen tearing.


Resolution: HVGA (480 x 320 pixels)



Color: 256K colors

The following figure shows the connections between the MSM7225A and the LCD.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

The following table describes the signal definitions.
Category

Description

Name in the Circuit
Network

MSM7225A GPIO/PM8029
MPP

Power supply

Digital power supply
input

VREG_S3

VREG_S3 (PM8029)

Analog power input

VREG_L12_2P85

VREG_L12_2P85 (PM8029)

MIPI data

MIPI_DSI_LANE1_P

MIPI data

MIPI_DSI_LANE1_N

Synchronization
signal

Frame synchronization
clock

MDP_VSYNC_P

GPIO97

Clock signal

MIPI clock

MIPI_DSI_CLK_P

MIPI clock

MIPI_DSI_CLK_N

Control signal

Reset signal

LCD_RESET_N

GPIO129

Identification
signal

LCD model identification

LCD_ID0

GPIO9 (PM8029)

LCD model identification

LCD_ID1

GPIO10 (PM8029)

Data

U8655N's LCD backlight control:
The U8655N uses a 3.5-inch LCD whose backlight is provided by six LEDs connected in
series. The backlight LEDs are controlled by the backlight driver chip TPS61160A. The
ground resistance of the driver chip pin FB is set to 10 Ω, providing up to 20 mA current to
the LEDs (duty:100%). The backlight brightness (driver output current) is controlled by the
PWM signal.
Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Backlight
signals

Issue 1.0 (2012-02-23)

The anode of the
backlight LED

LED_A

The anode of the backlight
LED

The cathode of the
backlight LED

LED_K

The cathode of the backlight
LED

Brightness control
signals from the LCD

PWM_OUT

Reserved

Brightness control
signals from the
phone's main chip

LCD_BL_PWM

GPIO1 (PM8029)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubling Display Failure

LCD fails to display

Reinstall the phone's
firmware. Is the problem
solved?

End

Check whether J1302 is
snapped in place. If it is not
in place, snap it again. Is the
problem solved?

Y
End

N
Replace the LCD. Is the
problem solved?

End

N
Return the phone
to the factory

9.4.2 Camera
The U8655N uses a 3.2-megapixel full-frame camera.
The 3.2-megapixel full-frame camera uses a 24-pin BTB connector and is controlled by the
I2C bus. The data is transmitted in MIPI mode.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Signal Name

Voltage

Description

CAM_VIO

VREG_S3

1.8

Controlled by the power
supply switch.

CAM_VIO

VREG_S3

1.8

Controlled by the power
supply switch.

VREG_CAM_2P85

VREG_L17(PM8029)

2.85

Power supply to the
camera autofocus motor

CAM_AVDD

VREG_L17(PM8029)

2.85

CAMIF_MCLK

GPIO_015(MSM7225A)

1.8

Camera reference clock

MCAMIF_SHDN

GPIO_119(MSM7225A)

1.8

Camera shutdown signal

CAM_VCM_PD_N

GPIO_07(MSM7225A)

1.8

Camera autofocus motor
control signal

I2C0_SCL

GPIO_060(MSM7225A)

1.8

I2C control signal

I2C0_SDA

GPIO_061(MSM7225A)

1.8

MCAMIF_RESET

GPIO_049(MSM7225A)

1.8

Reset signal

MCAMIF_ID

GPIO_9(MSM7225A)

1.8

Module supplier
identification

MIPI_CSI2_CLK_P

MIPI clock

MIPI_CSI2_CLK_N

MIPI clock

MIPI_CSI2_LANE1_P

Data communication
signal

MIPI_CSI2_LANE1_N

Data communication
signal

MIPI_CSI2_LANE0_P

Data communication
signal

MIPI_CSI2_LANE0_N

Data communication
signal

NOTE

The camera interface circuit is designed for compatibility with multiple types of cameras. The U8655N
uses a 3.2-megapixel full-frame camera, so the CAM_VCM_PD_N and VREG_CAM_2P85 lines are
not used.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting Camera Failure
Failure to take photos or
record video using the
camera
Y

Reinstall the phone's
firmware. Is the
problem solved?

End

N
Y
Is J1001 poorly soldered or
are its contacts defective?

Re-solder or replace
J1001

N
Y
Replace the
camera. Is the
problem solved?

End

Return the phone
to the factory

9.4.3 USB

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting USB Connection Failure

USB connection failure

Y
Use a normal USB
cable. Is the problem
solved?

End

N
Y
Is the 5-pin mini USB
connector poorly soldered?

Re-solder the USB
connector

N
Reinstall the
phone's firmware.
Is the problem
solved?

End

N
Return the phone
to the factory

9.4.4 Headset Jack
The headset jack is a 3.5-mm headset jack. When the headset jack has no headset inserted, the
headset jack's pin 3 and pin 4 are open, and the headset detection voltage is at high level.
After a headset is inserted, pin 3 and pin 4 are closed, and the headset detection voltage is at
low level, indicating the insertion of a headset. The HS_DETECT (GPIO86) pin is used to
detect the headset insertion.
The HSED_MICBIAS (PM8029/HSED_BIAS1) supplies power to the headset microphone.
The HSED_HSKEY_ADC (PM8029 MPP5) is used to detect the headset button press.
NOTE

The U8655N supports only LRGM headsets, and does not support LRMG headsets.

Issue 1.0 (2012-02-23)

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis



No sound comes from the headset during a call
Af ter a call is established, no
sound can be heard from the
headset
N
Is the in-call volume
set to a normal level?

End

Y
Y
Replace the headset. Is the
problem solved?

End

N
Is a headset icon
displayed on the
screen?

Replace the
headset jack

Y
Return the phone
to the f actory



Issue 1.0 (2012-02-23)

The headset button cannot be used to answer a call

Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.

U8655
Maintenance Manual

9 Principles and Failure Analysis
The headset button cannot be
used to answer a call

Y
Replace the headset.
Is the problem solv ed?

End

N
Is the voltage on J1101's
pin 4 at low level after the
headset is inserted?

N
Check that J1101 is
properly soldered.

Y
Return the phone
to the factory

9.4.5 Keys
The U8655N has six keys, three of which are the Menu, Home and Back keys on the
touchscreen panel.
The MSM7225A's GPIO_42 and GPIO_41 pins are connected to the volume up and down
keys. The side key FPC is connected to the PCBA via the ZIF connector J1605.
The Power key press is detected by the PM8029's KPD_PWR_ON pin. The Power key FPC is
connected to the PCBA using press-fit contacts.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting Key Failure

Key failure
N

Is the keypad on the
FPC in good contact
with the dome sheet?

Clean the
keypad and the
dome sheet

N
Are the FPC and ZIF
connector connected
properly?

Re-connect them

Y
Return the phone
to the factory

9.4.6 Status Indicator and Touch Key Backlight Circuits
The U8655N's status indicator (tricolor indicator) provides red, green and blue light sources
that are driven by the PM8029's three LED drivers.
Light
Source

Driver Pin (PM8029)

Description

Red

LED_RED_DRV_N (MPP3)

Adjusted using electric current

Green

LED_GREEN_DRV_N (MPP5)

Adjusted using electric current

Blue

LED_BLUE_DRV_N (MPP8)

Adjusted using electric current

The KYPD_DRV_N (PM8029) is used to adjust the brightness of the keypad's backlight, and
VPH_PWR is used to supply power to the backlight LEDs. The keypad backlight is provided
by two white LEDs. The light from the LEDs are transmitted to the key area using a light
guide film.
Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Keypad Backlight Driver
VPH_PWR

Power supply

Backlight power supply

KPD_DRV_N

Backlight driver pin

When this pin's voltage is at low
level, the two backlight LEDs
turns on.

9.4.7 Battery Connector

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.8 Accelerometer

Component
Pin
SCL

Network

MSM7225A Pin

Description

I2C1_SCL

GPIO_131

I2C bus

SDA

I2C1_SDA

GPIO_132

INT1

MEMS_INT1

GPIO_28

INT2

MEMS_INT2

GPIO_111

Accelerometer interrupt
signal
Accelerometer interrupt
signal (sleep)

9.4.9 Proximity and Illuminance Sensor
The U8655N has a proximity and illuminance sensor. The following figure shows the sensor
circuit.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Component Pin

Network

MSM7225A-0 Pin

Description

SCL

I2C1_SCL

GPIO_131

I2C bus

SDA

I2C1_SDA

GPIO_132

INT

PRO_INT

GPIO_17

3-in-1 interrupt signal

Functions


Detect the intensity of environmental light.



Detect the proximity of objects.

The phone's display does not
turn of f when near the user's
ear during a call
Y
Is the touchscreen panel's
illuminance sensor hole dirty
or blocked?

Clean the hole

N
Y

Reinstall the phone's
f irmware. Is the problem
solved?

End

N
Y
Is U1207 poorly soldered
or dirty?

Re-solder, clean
or replace U1207

Return the phone
to the f actory

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.10 Vibration Motor

The motor driver current is controlled by PM VIB_DRV_N.

Troubleshooting Vibration Failure
Vibration failure
Y
Reinstall the phone's
f irmware. Is the
problem solved?

End

N
Y
Replace the motor. Is the
problem solved?

End

N
Y
Is the voltage on
VIB_DRV_N equal to
the battery voltage?

Replace D902

N
Return the phone
to the f actory

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.11 Receiver
The receiver receives differential earphone output from the MSM chip. The following figure
shows the circuit.

The MSM chip's EARI output signal is connected to the receiver. Bypass capacitors are added
to the signal traces. The circuit shown in the previous figure is designed for compatibility.
L1508, L1510 and U1501 are reserved for the HAC function and are not soldered on the
U8655N. D1503 and D1504 are the ESD protection components on the receiver.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting the Failure that No Sound Can Be Heard During a Call
No sound is heard
during a call
N
Is the in-call volume
set to a normal level?

End

Does the phone mistakenly
detect the insertion of a
headset?

Replace the
headset connector

N
Y
Replace the
receiver. Is the
problem solved?

End

N
Return the phone
to the f actory

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.12 Microphone

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting the Failure that No Sound Can Be Heard by the Other Party
During a Call
No sound can be heard by
the other party during a call

Y
Reinstall the phone's
f irmware. Is the
problem solved?

End

N
N
Is the MIC_BIAS voltage
equal to 1.8 V?

Check U201

Y
Y
Replace the
microphone. Is the
problem solved?

End

N
Return the phone
to the f actory

9.4.13 Touchscreen Panel

The U8655N's 3.5-inch capacitive touchscreen panel has a touch key area containing three
touch keys. The backlight LEDs for the three touch keys are located on the PCBA. A light
guide film is used to guide light from the LEDs to the touch key area.
The following table describes the interfaces between the touchscreen panel, MSM7225A and
PM8029.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Touchscreen Panel
Interface

Description

VDD_2V8_TP

VREG_L12_2P85 (PM8029)

Touchscreen panel analog power supply,
2.85 V

VREG_S3

VREG_S3 (PM8029)

Touchscreen panel digital power supply and
I/O connector power supply, 1.8 V

TOUCH_INT

GPIO_82 (MSM7225A)

Touchscreen panel interrupt signal

I2C1_SCL

GPIO_131 (MSM7225A)

Touchscreen panel's I2C clock

I2C1_SDA

GPIO_132 (MSM7225A)

Touchscreen panel's I2C data

TOUCH_RST_N

GPIO_96 (MSM7225A)

Touchscreen panel reset signal

9.4.14 SIM Card
The MSM7225A is not compatible with the SIM card interface. The PM8029's MPP pins are
used to convert voltage levels of the signals for communication between the MSM7225A and
the SIM card.
The voltage of VREG_L16_UIM1 can be set to 1.5–3.05 V. The USIM interface's operating
voltage is usually 1.8 V or 3.0 V. The following table describes the voltage level conversion
interface of the PM8029.
Signal for Interfacing
with the MSM

Voltage Level

Signal for Interfacing
with the USIM Card

Voltage Level

UIM1_RESET
VREG_S3

UIM1_MSM_CLK
UIM1_MSM_DATA

UIM1_CLK

VREG_L16_UIM1

UIM1_DATA

(configured by the
phone's firmware)

NOTE

Considering that SIM card operations are frequent, transient-voltage-suppression (TVS) diodes are
added to the circuit to provide ESD and surge protection.

USIM card circuit

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.15 microSD Card
The microSD card connector's SD_DETECT pin is used to detect the insertion of a microSD
card. When a microSD card is inserted, the pin is grounded and its voltage is at low level.
When no microSD is inserted, its voltage is at high level. The U1402 is an EMI and ESD
protection component for the microSD card.
The following figure shows the circuit.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

9.4.16 NFC
U8655N supports NFC module function, and uses NFC control chip of NXP to receive and
process signal. when use NFC function normally, the battery cover must be covered because
of built-in antenna. the signal NFC_VEN_MOS which is the reset signal of NFC module is
controlled by NFC_VEN signal, this module uses a clock of 19.2MHz to ensure module work
properly.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

Issue 1.0 (2012-02-23)

9 Principles and Failure Analysis

U8655
Maintenance Manual

Issue 1.0 (2012-02-23)

9 Principles and Failure Analysis

U8655
Maintenance Manual

9 Principles and Failure Analysis

Troubleshooting the Failure of NFC swiping

Swiping card
failure

Update the phone's software,
Is the problem solved?

End

Is the antenna in
good contact with
metal dome?

Replace battery
covere with antenna

Is power output
Voltage normal?

Re-solder U4401

Y
Return to factory

Signal name

Description

Voltage or Waveform

NFC_VEN_MOS

NFC chip reset signal

The same voltage of battery

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

9 Principles and Failure Analysis

Signal name

Description

Voltage or Waveform

NFC_VEN

The reset signal from CPU

1.8V

NFC_TX1

Contactless Transmitter output1

NFC_TX2

Contactless Transmitter output2

VBAT

Battery power

Battery voltage 3.6V-4.2V

VREG_S3

power

1.8V

TCXO_OUT_NFC

Clock signal

19.2MHz

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

10 Solder Points on the PCB and BGA Chip

Solder Points on the PCB and BGA
Chip

Red (R: 255, G: 0, B: 0)

: Vacant point

Green (R: 0, G: 255, B: 0)
Blue (R: 0, G: 0, B: 255)

: Ground point
: Solder point

Magnified views of sections:
PM section

MSM7225A+NAND MCP section

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

10 Solder Points on the PCB and BGA Chip

Wi-Fi/Bluetooth/FM section

RTR8285A section

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

10 Solder Points on the PCB and BGA Chip

Complete PCB view:

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

Issue 1.0 (2012-02-23)

10 Solder Points on the PCB and BGA Chip

U8655
Maintenance Manual

Issue 1.0 (2012-02-23)

10 Solder Points on the PCB and BGA Chip

U8655
Maintenance Manual

11 Functional Tests

Functional Tests

11.1 MMI Test
On the Home, enter *#*#2846579#*#* to enter the MMI test mode. Press the Volume– key to
start a test. Touch the Menu key on the touchscreen panel to skip the current test and go to the
next step. Touch the Back key to return to the previous test.
NOTE


When no battery is installed or the battery voltage is low, the phone will indicate that the battery is
low and the MMI test cannot be started.



During a test, if you touch the Menu key on the touchscreen panel, the test will be skipped and
marked as a failed test.

No.

Category

Item

Test Method

SD card test

microSD card test

Automatically test the microSD card functions. If a
microSD card is found and is available, the test passes.
Otherwise, the test fails.
If this test passes, the next test automatically starts.

SIM card test

Automatically test whether the SIM card can be
recognized. If the SIM card cannot be recognized, a
message will be displayed, indicating that this test fails.
If this test passes, the next test automatically starts.

Battery test

Automatically test whether the battery is in place and
whether its power is sufficient. If this test fails, a message
will be displayed.
If this test passes, the next test automatically starts.

Keypad test

Keys

Press or touch all the keys.
When a key is pressed or touched, the color of the
corresponding key displayed on the screen will change
(from white to blue, or from blue to white). After all keys
are tested, press the Volume– key to start the next test.

LCD test

White screen

The LCD displays a white screen.
Press the Volume– key to start the next test.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

No.

Category

11 Functional Tests

Item

Test Method

Black screen

The LCD displays a black screen.
Press the Volume– key to start the next test.

Red and blue bars

The LCD displays red and blue bars.
Press the Volume– key to start the next test.

LCD backlight
and status
indicator test

LCD backlight and
status indicator

If the LCD backlight repeatedly turns on and off, the
LCD backlight is normal. The status indicator is normal if
its color repeatedly changes in the sequence of red, green
and blue.
Press the Volume– key to start the next test.

Keypad LED
test

Keypad backlight LEDs

If the keypad backlight repeatedly turns on and off, the
backlight LEDs are normal.
Press the Volume– key to start the next test.

Camera test

Automatically test the camera. The phone's camera is
turned on, and the LCD displays the preview. Check the
image quality visually and test the camera's response
speed to determine the camera's performance.
Press the Volume– key to start the next test.

Touch screen
test

Touch screen panel

There are three vertical gridlines which are composed of
a group of squares, one is in middle, the other are on
edge, Place your figure on the touch screen panel, and
slide your figure sweep each square along the gridline.
The areas near the route that your figure passes should
turn red. it will fail if the finger sweeps outside of these
squares.
Press the Volume– key to start the next test.

Approach test

Environmental
light test

The proximity and
illuminance sensor's
proximity detection
function

Place the light shielding plate approximately 4 mm above
the light hole. If a phone icon is displayed nearby the
portrait, the function is normal.

The proximity and
illuminance sensor's
function to sense
environmental light

Check whether the environmental light sensing data is
detected: Use your hand to block the light hole, the light
sensing number will decrease approximately 10 if the
illuminance sensor functions properly.

If this test passes, the next test automatically starts.

If this test passes, the next test automatically starts.
12

Vibration test

Vibration motor

The motor will vibrate intermittently.
Check whether the vibration (including the vibration
sound) is normal.
Press the Volume– key to start the next test.

Speaker test

Automatically test the speaker. (Do not insert the
headset.) If the speaker emits sound during the test, it is
normal.
Press the Volume– key to start the next test.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

11 Functional Tests

No.

Category

Item

Test Method

Mobile phone
mic loopback
test

Main microphone
(located near the USB
port)

Do not insert the headset. Touch the Record button.
Speak to the main microphone, and then touch the Play
button. If the main microphone is normal, you can hear
the voice recording from the receiver.
Press the Volume– key to start the next test.

Mobile phone
loopback test

Secondary microphone
(located above the
camera at the phone's
rear)

Do not insert the headset. Touch the Record button.
Speak to the secondary microphone, and then touch the
Play button. If the secondary microphone is normal, you
can hear the voice recording from the receiver.
Press the Volume– key to start the next test.

Dual MIC test

Main and secondary
microphones

Do not insert the headset. Touch the Record button.
Speak to the phone as you do during a call, and then
touch the Play button. If the main and secondary
microphones are normal, you can hear the voice
recording from the receiver.
Press the Volume– key to start the next test.

Mobile phone
Headset
loopback test

Insert the headset. Touch the Record button. Speak to the
headset microphone, and then touch the Play button. If
the headset is normal, you can hear the voice recording
from the headset's earphones.

Headset

Keep the headset inserted. Press the Volume– key to start
the next test.
18

FM test

The testing software will detect whether a headset is
inserted. If no headset is inserted, a message requesting a
headset to be inserted will be displayed. After a headset is
inserted, the phone will search for and play an FM
channel. Three frequencies (88 MHz, 98 MHz and 107
MHz) will be tested. The 88 MHZ frequency will be
tested first. To test the next frequency, touch Next
Channel.

FM test

Remove the headset. Press the Volume– key to start the
next test.
19

Headset Wire
control test

Headset button test

Insert the headset. The IN icon will turn green.
Press the headset button, and the round dot will become
smaller. Remove the headset, and the OUT icon will turn
green.
Press the Volume– key to start the next test.

Bluetooth test

Automatically test the Bluetooth functions.
During the test, the phone will search for Bluetooth
devices, and display the MAC addresses of the Bluetooth
devices that have been found. (Note: This test requires
another device with Bluetooth enabled.)
Press the Volume– key to start the next test.

Issue 1.0 (2012-02-23)

U8655
Maintenance Manual

11 Functional Tests

No.

Category

Item

Test Method

Gravity sensor
test

Accelerometer

The LCD displays the current acceleration in the X, Y
and Z axes. Place the phone in a position where the
angles between the X, Y and Z axes are 45°. If the
acceleration in the X, Y and Z axes is equal to each other,
the phone passes this test.
If this test passes, the next test automatically starts.

WiFi test

Wi-Fi test

Automatically test the Wi-Fi functions.
During the test, the phone will search for nearby hotspots,
and display the MAC addresses of the hotspots that have
been found. (Note: This test requires an active hotspot in
the testing environment.)
Press the Volume– key to start the next test.

Display test

Displaying test results

Display the MMI test results.
Failed test items will be listed.

11.2 Voice Call Test
1.

Install a UIM card and a battery on the phone.

Press the Power key to power the phone on.

Check whether the signal strength displayed on the LCD is normal (given that the
network is normal).

Make a call to a fixed-line phone, and check the voice quality during the call.

If no problems are found during the test, finish the voice call test. If any problems are
found, troubleshoot the phone or send it to an advanced service site for repair.

Issue 1.0 (2012-02-23)

Source Exif Data:

File Type                       : PDF
File Type Extension             : pdf
MIME Type                       : application/pdf
PDF Version                     : 1.5
Linearized                      : No
Page Count                      : 72
Language                        : zh-CN
Title                           : Release Notes
Author                          : Wuguoyan KF25758
Creator                         : Microsoft® Office Word 2007
Create Date                     : 2012:10:29 14:05:19
Modify Date                     : 2012:10:29 14:05:19
Producer                        : Microsoft® Office Word 2007

EXIF Metadata provided by EXIF.tools

Huawei Release Notes F Tanjim Qmobile Call Centre Singer Y200 U8655 1. 51053288 U8655N(MTC965) Maintenance Manual V1.0

Navigation menu

Versions of this User Manual:

Views

Navigation