Soundcraft Cps2000 Users Manual Corel Ventura COVERPG.CHP

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2015-02-02

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SOUNDCRAFT CPS2000

Console Power Supply

User and Technical Manual

IMPORTANT: please read this manual carefully before

connecting your Soundcraft console power supply to

the mains for the first time.

For your own safety and to avoid invalidation of the

warranty all text marked with these Warning Symbols

should be read carefully.

Parts of the design of this product may be protected by world-wide patents.

Part No. ZM0198-05

Soundcraft is a trading division of Harman International Industries Ltd.

Information in this manual is subject to change without notice and does not

represent a commitment on the part of the vendor. Soundcraft shall not be liable for

any loss or damage whatsoever arising from the use of information or any error

contained in this manual, or through any mis-operation or fault in hardware

contained in the product.

No part of this manual may be reproduced, stored in a retrieval system, or

transmitted, in any form or by any means, electronic, electrical, mechanical, optical,

chemical, including photocopying and recording, for any purpose without the

express written permission of Soundcraft.

It is recommended that all maintenance and service on the product should be

carried out by Soundcraft or its authorised agents. Soundcraft cannot accept any

liability whatsoever for any loss or damage caused by service, maintenance or

repair by unauthorised personnel.

Harman International Industries Ltd.

Cranborne House

Cranborne Road

Potters Bar

Herts.

EN6 3JN

England

Tel: 01707 665000

Fax: 01707 660482

www.soundcraft.com

Contents

Introduction 1

Mains Voltage Selection 2

Operating Voltage Range 4

Replacing Mains Fuse 4

Warranty 5

Recommendations for Installation 7

PSU Linking 10

Dimensions 11

Technical Specification 13

Circuit Description 15

Parts List 25

Fan Control 35

Technical Drawings 39

Introduction

Introduction 1

IMPORTANT SAFETY INSTRUCTIONS

·Read these instructions.

·Keep these instructions.

·Heed all warnings.

·Follow all instructions.

·Do not use this apparatus near water.

·Clean only with a dry cloth.

·Do not block any ventilation openings. Ventilation should not be impeded by covering the ventilation

openings with items such as newspapers, table cloths, curtains etc. Install in accordance with the

manufacturer’s instructions.

·Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including

amplifiers) that produce heat.

·Do not defeat the safety purpose of a polarised or grounding type plug. A polarised plug has two blades with

one wider than the other. A grounding type plug has two blades and a third grounding prong. The wide

blade or the third prong are provided for your safety. If the provided plug does not fit into your outlet, consult

an electrician for replacement of the obsolete outlet

·Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles and

the point where they exit from the apparatus.

·Only use attachments/accessories specified by the manufacturer.

·Use only with the cart, stand, tripod, bracket or table specified by the manufacturer, or sold with the apparatus.

When a cart is used, use caution when moving the cart/apparatus combination to avoid injury from tip-over.

·Unplug this apparatus during lightning storms or when unused for long periods of time.

·Refer all servicing to qualified service personnel. It is recommended that all maintenance and service on the

product should be carried out by Soundcraft or its authorised agents. Soundcraft cannot accept any liability

whatsoever for any loss or damage caused by service, maintenance or repair by unauthorised personnel.

Servicing is required when the apparatus has been damaged in any way, such as power-supply cord or plug

is damaged, liquid has been spilled or objects fallen into the apparatus, the apparatus has been exposed to

rain or moisture, does not operate normally, or has been dropped.

·No naked flame sources, such as lighted candles, should be placed on the apparatus.

·WARNING: To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture.

Do not expose the apparatus to dripping or splashing and do not place objects filled with liquids, such as

vases, on the apparatus.

·Terminals marked with the lightning symbol are hazardous live and the external wiring connected to these

terminals requires installation by an "instructed person" or the use of ready made leads or cords.

·THIS APPARATUS MUST BE EARTHED. Under no circumstances should the safety earth be

disconnected from the mains lead.

·The mains supply disconnect device is the mains plug. It must remain accessible so as to be readily operable

when the apparatus is in use.

·If any part of the mains cord set is damaged, the complete cord set should be replaced. The following

information is for reference only.

·The wires in the mains lead are coloured in accordance with the following code:

·Earth (Ground):Green and Yellow (US - Green/Yellow)

·Neutral:Blue (US - White)

·Live (Hot):Brown (US - Black)

·As the colours of the wires in the mains lead may not correspond with the coloured markings identifying the

terminals in your plug, proceed as follows:

·The wire which is coloured Green and Yellow must be connected to the terminal in the plug which is marked

with the letter E or by the earth symbol

·The wire which is coloured Blue must be connected to the terminal in the plug which is marked with the

letter N

·The wire which is coloured Brown must be connected to the terminal in the plug which is marked with the

letter L

·Ensure that these colour codes are followed carefully in the event of the plug being changed

·This unit is capable of operating over a range of mains voltages as marked on the rear panel. It is important

to ensure that the correct mains fuse is fitted before switching on the unit.

2Introduction

Introduction

WARNING: THIS APPARATUS MUST BE EARTHED

The CPS2000 is a linear power supply which, like other linear supplies, produces DC

voltages by rectifying, smoothing and regulating AC voltages from the secondary

windings of a mains transformer. Soundcraft mixing consoles employ a number of

dc voltage supply levels in their operation and these are all provided at the output of

each supply unit.

In regulating these voltages there is considerable heat generated, the dissipation of

which is achieved through a substantial heat sink on each side of the unit. Two fans

are incorporated which draw air over the heatsinks to provide adequate heat dissipation

for the regulators and reduce the outer case temperature.

The CPS2000 is designed for installation in a 19" rack unit, occupying 4U of rack

height. Refer to the section "RECOMMENDATIONS FOR INSTALLATION" on

Page 7.

LEDs are provided on the front panel to show the operation of the regulating circuits,

and a digital voltmeter monitors the mains supply voltage.

The CPS2000 may be linked to a second CPS2000 to provide automatic power backup

in the event of one of the units failing.

MAINS VOLTAGE SELECTION.

Special attention should be paid to the following information:

Do not change the voltage setting without first turning

the unit off and unplugging the mains lead. Ensure that

the cover plate over the mains voltage selection

switches is replaced after correct voltage selection

has been made and that the cover plate is positioned

to show the correct mains voltage.

This unit is capable of operating over a wide range of mains voltages by means of a

comprehensive set of selectable voltage settings. It is important to ensure that the

correct voltage setting has been selected for the level of local mains voltage supply,

for safe, uninterrupted operation of the unit.

There are two mains voltage selection switches behind a cover plate on the front of

the unit. Voltage selection is achieved by moving the switches using a screwdriver

blade, into the correct positions, as shown by the symbols marked on the front panel.

In this way the unit is set up for operation at one of the following ranges of mains

supply:

NOMINAL VOLTAGE OPERATING VOLTAGE RANGE

Vrms AC Vrms AC

230 195-253

200 170-220

115 98-126

100 85-110

Introduction 3

200V

230V

100V

115V

Mains Voltage Selector Positions

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

RISK OF ELECTRIC SHOCK

DO NOT OPEN

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

NO USER SERVICEABLE PARTS INSIDE

PIN 1, 2, 3, 4 +17V 16A

9, 10, 11, 12 -17V 16A

13 +48V

18 +8V

NOT USED

1.25A

5, 6, 7, 8 +0V

16, 17 0V

0.5A

14, 15 CHASSIS GROUND

( BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

(BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

DC POWER OUT

TO CONSOLE

DC POWER OUT

TO CONSOLE

DC POWER IN

FROM STANDBY SUPPLY

DC POWER IN

FROM STANDBY SUPPLY

TO REDUCE THE RISK

OF FIRE OR ELECTRIC SHOCK

DO NOT EXPOSE THIS UNIT

TO RAIN OR MOISTURE

DO NOT COVER ANY VENTILATION

SLOTS AS THIS MAY CAUSE THE

EQUIPMENT TO OVERHEAT

WARNING:

MAINS VOLTAGE SELECTION

200V

100V

115V

230V

200V

230V

100V

115V

48V

HIGH TEMP

17V

CLEAN FAN FILTERS REGULARLY

DO NOT COVER

ANY VENTILATION SLOTS, AS

THIS MAY CAUSE THE EQUIPMENT

TO OVERHEAT

WARNING:

17V

ACCESS TO MAINS VOLTAGE SELECTION SWITCHES

WARNING: DISPLAY MAINS VOLTAGE SETTING IN

SIDE WINDOW WHEN REFITTING COVER PLATE.

UNDER COVER PLATE.

ENSURE CORRECT MAINS VOLTAGE

SETTING AND CORRECT FUSE BEFORE

CONNECTING MAINS SUPPLY.

DO NOT SWITCH MAINS VOLTAGE SETTINGS

WHILE MAINS SUPPLY IS CONNECTED.

DOTS LIGHT WHEN MAINS LOW

POWER

OFF

MAINS VOLTAGE

CONSOLE POWER SUPPLY

CPS

000

MAINS FUSE:

CAUTION:

ATTENTION:

100V/230V USE T10.0A/250V

TO REDUCE THE RISK OF

AFIN DE REDUIRE LE

RISQUE DE FEU, REMPLACER SEULEMENT

AVEC FUSIBLE DE MEME TYPE.

FIRE, REPLACE WITH SAME

TYPE FUSE ONLY.

Front and Rear Panel Views

4Introduction

OPERATING VOLTAGE RANGE

It is very important to use the correct mains voltage selection. A wide operating range

of mains voltages is provided to enable the unit to function down to only 85Vrms on

the mains supply. This facility is incorporated to overcome the problems that some

power supplies have with internal regulation when operating from a poorly regulated

mains supply.

Do not operate the PSU with a consistently high (above

nominal) reading on the mains meter. Operation with

the mains higher than +10% may cause serious

damage

The mains meter is essentially a peak-reading device, as it is the peak value of the

mains waveform which is the most important factor in providing the correct mains

voltage to the power supply. For this reason, and because with long power cables it

is common for the mains waveform to become distorted, the indication of the meter

may not agree with readings taken with the usual types of quasi-RMS reading

testmeter.

Note that the meter measures the voltage actually available at the PSU, and therefore

will indicate any voltage drop on mains supply wiring.

REPLACING MAINS FUSE.

In the event of incorrect switching of the mains voltage selectors, a mains power surge

or underrated fuse value, the mains fuse in the front panel will blow and the CPS2000

will not function. Switch the ON/OFF switch to the OFF position. Check the fuse

and replace if necessary; also check that the voltage selection is correct for the mains

supply level before switching the unit ON again.

To avoid risk of fire replace only with the correct value

fuse, as indicated on the unit.

In the event of repeated failure of the mains fuse consult the Soundcraft dealer from

where the unit was purchased.

This unit contains no user serviceable parts. Refer all

servicing to a qualified service engineer, through the

appropriate Soundcraft dealer.

Introduction 5

1Soundcraft is a trading division of Harman International Industries Ltd.

End User means the person who first puts the equipment into regular operation.

Dealer means the person other than Soundcraft (if any) from whom the End User

purchased the Equipment, provided such a person is authorised for this purpose by

Soundcraft or its accredited Distributor.

Equipment means the equipment supplied with this manual.

2 If within the period of three years from the date of delivery of the Equipment to the

End User it shall prove defective by reason only of faulty materials and/or

workmanship to such an extent that the effectiveness and/or usability thereof is

materially affected the Equipment or the defective component should be returned to

the Dealer or to Soundcraft and subject to the following conditions the Dealer or

Soundcraft will repair or replace the defective components. Any components

replaced will become the property of Soundcraft.

3 Any Equipment or component returned will be at the risk of the End User whilst in

transit (both to and from the Dealer or Soundcraft) and postage must be prepaid.

4 This warranty shall only be available if:

a) the Equipment has been properly installed in accordance with instructions

contained in Soundcraft’s manual; and

b) the End User has notified Soundcraft or the Dealer within 14 days of the defect

appearing; and

c) no persons other than authorised representatives of Soundcraft or the Dealer have

effected any replacement of parts maintenance adjustments or repairs to the

Equipment; and

d) the End User has used the Equipment only for such purposes as Soundcraft

recommends, with only such operating supplies as meet Soundcraft’s specifications

and otherwise in all respects in accordance Soundcraft’s recommendations.

5 Defects arising as a result of the following are not covered by this Warranty: faulty

or negligent handling, chemical or electro-chemical or electrical influences,

accidental damage, Acts of God, neglect, deficiency in electrical power,

air-conditioning or humidity control.

6. The benefit of this Warranty may not be assigned by the End User.

7. End Users who are consumers should note their rights under this Warranty are in

addition to and do not affect any other rights to which they may be entitled against

the seller of the Equipment.

Warranty

6Introduction

Recommendations for

Installation of the CPS 2000

Installation 7

Recommendations for Installation

The CPS2000 power supply is provided with front panel fixing holes for 19"

rack-mounting and will occupy 4U of rack space. Rear support should be provided

when fitted in a 19" rack.

The CPS2000 is a heavy unit (30kg,) and should be

regarded as a two-man lift. Take suitable precautions

when lifting

As with any power supply that contains a large mains-voltage transformer, it is

preferable to provide a degree of physical isolation of the unit from other electronic

equipment, particularly that which carries low level audio signals, to avoid any

possible hum pick-up. For this reason the unit is used with a long (6.5 metres) output

cable to enable it to be positioned away from the mixing console.

For the same reason, when rack-mounting it is preferable to avoid locating the unit

adjacent to signal processing equipment.

It should be noted that if a complete rack containing a CPS2000 unit is to be operated

from a different mains supply level, then the unit should be withdrawn from the rack

in order to reselect the mains voltage setting, at the same time as resetting any other

equipment.

The other important consideration when rack-mounting the unit is the need for natural

convection of air over the case and an unrestricted air flow through the unit. Note that

air is drawn in at the front of the unit and expelled through the rear panel.

Good ventilation BELOW the unit, in the floor or back of the rack, and similarly

ABOVE the unit, at the top of the rack, will ensure a path for continuous air flow.

Other equipment in the rack which is known NOT to produce a significant amount of

heat should be mounted BELOW the unit. Equipment that also relies on good air flow

within the rack (ie. most power amplifiers and other power supplies) should be given

due consideration and some space should be provided between such units and between

these and the CPS2000 unit. Forced convection, by means of a fan-tray, may be

desirable in this situation.

The CPS2000 will operate as a free-standing unit

without requiring any special cooling arrangement,

but should not be allowed to be accidentally or

deliberately covered over in any way.

Do not operate the unit with the top cover removed as

this exposes hazardous voltages.

The filters on the cooling fans must be inspected

regularly and cleaned if necessary to maintain good

airflow through the unit. This will be particularly

important if the unit is used in a dusty environment.

8Installation

Finally, some consideration should be given to the earthing arrangement of the system

at the centre of which are the console and the CPS2000 (and any other Soundcraft

power supply units). The console chassis is earthed, through the mains earth, via the

power supply. When rack-mounting the CPS2000(and any other Soundcraft power

supply units) care should be taken to avoid any possible ‘ground loops’ in the system

which would introduce audible hum to otherwise clean audio signals. Ground loops

may occur where signal processing equipment, patched to the console, has its signal

earth commoned to the equipment chassis. The ground loop is formed if this chassis

and the power supply chassis are in electrical contact through the fixing rails they

share in the rack. To avoid this situation, standard isolating washers may be employed

when fixing the power supply (or supplies) or any other unit into the rack.

W A R N I N G : THIS APPARATUS MUST BE

EARTHED. Under no circumstances should the mains

earth be disconnected from the CPS2000 power supply

unit.

GENERAL

As with all electrical/electronic equipment care should be taken when handling this

unit. Avoid general mishandling and do not drop. Avoid storage and operation in

dusty locations and do not expose to corrosive atmospheres.

To avoid risk of fire do not expose this unit to rain or

moisture.

Retain all packaging for transportation in the event of the unit requiring servicing.

Retain this manual safely, along with all other relevant documents.

For touring/mobile transportation it is advisable to install the CPS2000 in a flight case

to provide mechanical protection. Refer to your Soundcraft dealer for a suitable case.

Where the CPS2000 is enclosed in a touring case, provision must be made for adequate

ventilation to the rear of the unit to ensure unrestricted supply of air for the cooling

fan.

Use only the 16 Amp mains lead supplied, no other

type is to be used.

Use only the DC output lead supplied, no other type is

to be used.

Installation 9

PSU Linking

Link the second PSU to the first as shown in the following diagram.

Note that the linking cable is included when a spare CPS2000 is ordered.

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

RISK OF ELECTRIC SHOCK

DO NOT OPEN

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

NO USER SERVICEABLE PARTS INSIDE

PIN 1, 2, 3, 4 +17V 16A

PIN 1, 2, 3, 4+17V 16A

9, 10, 11, 12 -17V 16A

13 +48V

18 +8V

19 NOT USED

NOT USED

1.25A

5, 6, 7, 8 +0V

5, 6, 7, 8+0V

16, 17 0V

0.5A

14, 15 CHASSIS GROUND

( BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

(BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

DC POWER OUT

TO CONSOLE

DC POWER OUT

TO CONSOLE

DC POWER IN

FROM STANDBY SUPPLY

DC POWER IN

FROM STANDBY SUPPLY

TO REDUCE THE RISK

OF FIRE OR ELECTRIC SHOCK

DO NOT EXPOSE THIS UNIT

TO RAIN OR MOISTURE

DO NOT COVER ANY VENTILATION

SLOTS AS THIS MAY CAUSE THE

EQUIPMENT TO OVERHEAT

WARNING:

CAUTION

RISK OF ELECTRIC SHOCK

DO NOT OPEN

RISK OF ELECTRIC SHOCK

DO NOT OPEN

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

AVIS: RISQUE DE CHOC ELECTRIQUE

- NE PAS OUVRIR

NO USER SERVICEABLE PARTS INSIDE

PIN 1, 2, 3, 4 +17V 16A

PIN 1, 2, 3, 4+17V 16A

9, 10, 11, 12 -17V 16A

13 +48V

18 +8V

19 NOT USED

NOT USED

1.25A

5, 6, 7, 8 +0V

5, 6, 7, 8+0V

16, 17 0V

0.5A

14, 15 CHASSIS GROUND

( BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

(BOTH DC CONNECTORS HAVE

IDENTICAL PINOUT )

DC POWER OUT

TO CONSOLE

DC POWER OUT

TO CONSOLE

DC POWER IN

FROM STANDBY SUPPLY

DC POWER IN

FROM STANDBY SUPPLY

TO REDUCE THE RISK

OF FIRE OR ELECTRIC SHOCK

DO NOT EXPOSE THIS UNIT

TO RAIN OR MOISTURE

DO NOT COVER ANY VENTILATION

SLOTS AS THIS MAY CAUSE THE

EQUIPMENT TO OVERHEAT

WARNING:

To Console

10 Installation

Dimensions

All dimensions in millimeters

Installation 11

12 Installation

Technical Specification

Technical Specification 13

Technical Specification

MAINS INPUT VOLTAGE RANGE:

230/200/115/100 V AC +10% / -15% @ 50/60Hz

RATED INPUT POWER (Max):

980 WATTS

MAINS FUSE RATING:

Use T10AL/250V (slow-blow).

OUTPUTS

DC. VOLTAGE RAIL MAX. OUTPUT CURRENT

+17V 16.00 AMPS

-17V 16.00 AMPS

+48V 0.30 AMPS

+8V 1.25 AMPS

All voltage and current measurements are to be taken

at the console-end of the power supply cable.

OPERATING TEMPERATURE RANGE (Ambient):

-10 TO +40°C.

HUMIDITY:

Similar unit tested at 0-90% RH non-condensing +/-5% Relative Humidity

at 40 °C for 16 hours. Load switched between 20% and 100% at regular

30 minute intervals.

OVERALL DIMENSIONS:

HEIGHT: 177.00mm. (4U)

WIDTH: Chassis 440.00mm.

Front panel 482.60mm.

DEPTH: (excl. handles) 436.00mm.

WEIGHT:

(Excl. packing): 30Kg

14 Technical Specification

Circuit Description

CAUTION:THE FOLLOWING SECTIONS ARE FOR USE

BY QUALIFIED SERVICE PERSONNEL ONLY. TO

REDUCE THE RISK OF ELECTRIC SHOCK, DO NOT

PERFORM ANY SERVICING, OTHER THAN THAT

CONTAINED IN PREVIOUS SECTIONS, UNLESS YOU

ARE QUALIFIED TO DO SO.

Circuit Description 15

Circuit Description

INTRODUCTION.

The CPS2000 power supply provides +/-17V at 16 Amps, +8V at 1.25 Amp, and +48V

at 0.3 Amp. The main PCB (SC3804) is in LH and RH halves. The LH PCB carries

the +17V and +48V supplies. The RH PCB carries the -17V and +8V supplies. A

separate PCB (SC3817) carries the mains voltage selector switches at the front of the

unit.

THE +/- 17V RAILS. SC3804

This consists of two identical +17V supplies connected together to give +/-17V.

Each 17V supply is a linear regulator with conventional fullwave rectification and a

large (100,000uF) reservoir capacitor. This is combined with a second power supply

that powers the driver transistors, the cooling fan, and the digital mains meter. The

main series pass elements are 250W discrete bipolar transistors connected in parallel

with suitable current-sharing precautions and mounted on a fan-cooled heatsink. The

voltage reference and servo control amplifier is provided by a 723 regulator IC. The

circuitry of the +17V regulator is described in detail below:

The +17V Supply. (LH PCB)

The transformer secondary is fused by means of 32 Amp Safeclip (BS88) fuses

mounted in holders on the floor of the chassis. They are NOT intended for customer

replacement. A spare fuse will be provided, but it is stressed that these fuses will only

blow in the event of catastrophic failure, such as a major short in the wiring or a failed

bridge rectifier.

The fullwave bridge rectifier is mounted on the heatsink, at the hottest end as it is the

most heat-tolerant of the semiconductors. The reservoir capacitors are mounted by

clips on the floor of the chassis. For safety reasons, the reservoir capacitor is

discharged by bleeder resistor R9 at switchoff; this takes about 30 seconds. A red

warning LED on the PCB is on whenever the capacitor is charged. The unregulated

DC is approx +26 to +29V.

The 723 IC contains a 7.15V nominal Zener diode, defining the voltage that appears

at Pin 6. Zener references generate appreciable noise, and this, plus any ripple, is

filtered out by R10,C10. R10 is in series with the positive input of the servo opamp

(Pin 5) and is made roughly equal in resistance to the feedback divider R16,17 etc to

minimise bias-current offsets.

The feedback divider R16,17,18 & PR1 derives a fraction of the output voltage and

delivers it to the negative input of the servo opamp. (Pin 4) The negative feedback

keeps this point also at 17.15V, so the actual output voltage is determined by the

feedback divider ratio, which is trimmed over a narrow range by PR3.

The output of the servo opamp controls the output through TR8, which is an emitter

follower driving the parallel pass devices TR4,5,6. R41 is included for diagnostic

purposes, so that the current being supplied by the 723 (only a few mA) can be

measured. The power supply to TR8 is taken from the +12V supply. This has its 0V

side connected to the positive unregulated DC supply of 26 - 29V, (at nominal mains)

giving a total voltage of approx 38 - 41V for the driver; this also powers the 723 IC.

This subrail markedly reduces the minimum drop across the pass elements and

therefore increases the efficiency.

16 Circuit Description

The 723 IC is powered through R11, which allows ripple filtering by C9, and voltage

protection by DZ1,2. These Zeners are not required to reduce ripple; their function is

purely protective, preventing the 40V Vmax spec of the 723 being exceeded should

the mains voltage rise above nominal.

The current through the pass devices TR4-7 is shared equally due to the

current-sharing resistors R35-45. The drop across these at full load is approx 200mV

which is more than enough to swamp Vbe differences in the main transistors.

50 Amp Schottky diode D7 on the output allows supplies to be paralleled for

redundancy.

The Mains Voltage Meter.

The incoming mains voltage is continuously indicated on the front panel by a 3.5 Digit

Panel Meter. (DPM) This is powered from a +5V supply derived from the +12V subrail

by 7805 regulator REG2.

The +5V supply is reduced to +2.5V by R30,31, and buffered by IC2-A to generate a

half-rail for the DPM input.

The incoming mains is monitored by differential amplifier IC1-A, which looks at the

voltage between Live and Neutral; this avoids problems with having one side of the

meter connected to Earth, which is often not at quite the same potential as Neutral.

The Voltage is picked off via two special BSI safety-approved 680K resistors on the

voltage select PCB (SC3817) which connect to CN3. The circuitry around IC1-A

(R21-24) gives unity gain, but the presence of the 680K resistors on the input gives

suitable scaling of the 50Hz signal.

The signal is applied to precision full-wave rectifier IC1-B, IC2-B via DC-blocking

cap C5; this circuit is biased by the +2.5V halfrail. The rectified output is smoothed

by C6 and scaled by R39 and PR1 before applying it to the DPM input on CN1 Pin

8. (IN HI)

Note the DPM has a differential input, so the cold side (IN LO, Pin 7) is connected to

the +2.5V halfrail.

The Mutual Shutdown System.

Equipment containing some kinds of op-amp is vulnerable to damage when only one

of the +/-17V rails fails, as in this case excessive supply currents can be drawn,

damaging fuse resistors on the modules.

When both 17V supplies are working normally, current flows through DZ8, OPTO1,

and across to the RH PCB. OPTO1 is on so the base drive to TR22 is shunted away

and the 723 works normally. Likewise, TR24 is kept on via R100, and ensures TR28

stays off.

If either supply fails there is insufficent voltage to keep DZ8 conducting, and current

flow ceases in the mutual shutdown line. TR22 is turned via the special supply

generated by D13, C26, and the internal node of the 723 IC3 is pulled down to ground,

turning it off. Likewise, in the -17V supply, TR28 is turned via the special supply

generated by D14, C25, and the internal node of IC4 is pulled down to ground, turning

it off.

C27,30 delay the action of mutual shutdown sufficiently to allow the supplies to start,

as they may not rise to working voltage at exactly the same rate.

Circuit Description 17

When shutdown has ocurred, the supply is reset by turning the mains briefly off and

on. R100 discharges C25 so that the circuit is ready for use at the next switch-on. The

special supplies generated by D13, C26, and D14, C25, are designed to discharge very

quickly at power-off, and it should not be necessary to turn the PSU off for more than

a second to reset it.

Overcurrent Protection.

The simplest form of overcurrent protection is the constant-current system; when an

attempt is made to draw excessive current, the output voltage is reduced so that no

more than a fixed maximum can be drawn. The high current capability of this PSU

means that constant current protection alone is not practical as the dissipation in the

pass devices is too high for the cooling system to deal with, and in the long term they

will overheat.

The standard answer to this problem is foldback current-limiting. Once again the

output voltage is reduced to prevent excessive current flow, but it is more severely

reduced so that the current flowing is not limited to a fixed maximum, but to a value

lower than that which triggered the protection originally. This greatly reduces the

dissipation in the supply in protection mode.

This system accomplishes its task, but can give trouble as the supply may work

perfectly into a resistive test load but not start into a real console load. The problem

is that a mixing console is essentially a constant-current load; as the supply voltage is

increased, almost the full current is drawn when only 2 or 3 volts are applied. There

are thus two stable states, with rails normal and the full current drawn, or with the

supply shut down to the few volts that will cause the foldback current to flow. When

the supply is switched on, it tends to stick in the second of these two states.

The CPS2000 avoids this problem by implementing constant-current protection that

causes complete shutdown (rather than foldback) after a fixed time delay. This is

described for the +17V supply; the -17V supply operates identically.

The first part of the problem is to measure the output current without dropping 0.6V

across a resistor to turn on a protection transistor. At 16 Amps the losses in this drop

would be unacceptable. Therefore supply current is measured by the voltage drop

across 0.05R resistors (R35,36 in parallel) which carry a quarter of the output current

and so drop 200 mV at full load. This is compared with a 200mV reference voltage

across R86, derived from bands-gap reference IC8 which sits on the output rail, by

differential amplifier TR18,19. When the input to TR19 exceeds the 200mV applied

to TR18, TR19 conducts and pulls down the internal 723 node at pin 13, reducing the

output voltage.

This causes current to cease in the mutual shutdown line, as described above, and after

a brief delay caused by C27,30, both 17V supplies are shut down.

ISSUE 8 operates exactly as above. The only difference is that the differential

amplifier TR18,19 has its tail fed from a negative subrail at approx -26V. This subrail

is generated from the AC input to the PCB by charge-pump C41,42,D22,23. The

resulting negative voltage is stabilised by 8V2 Zener DZ10, and applied to R73. This

keeps the tail current of TR18,19 more constant, and so maintains the

transconductance (current out for voltage in) at a higher level, giving closer feedback

control of current-limiting under extreme conditions. The RH PCB operates

identically.

18 Circuit Description

Undervoltage warning.

The supply gives a warning indication when the mains voltage has fallen so low that

regulation is about to be lost. The Headroom Indicator subsystem illuminates all the

decimal points on the DPM, giving a clear signal that something is amiss.

The voltage across the pass transistors is monitored by TR3; when this voltage falls

too low, TR3 turns off, turning off TR1. TR1 collector is then pulled up to +40V by

R26, charging C7 through D5, and so turning on TR2. This connects the DPM decimal

point connections to the local 0V (actually +26 TO +29V above supply 0V) via

current-limiting resistors R32-34. The peak-hold action of D5/C7 is required as the

voltage across the pass transistors includes a large ripple content that would leave the

decimal points rather dim if they were being strobed at 100 Hz.

An identical circuit (TR9, TR10) monitors headroom in the -17V supply. The voltage

across the pass transistors is monitored by TR10. When this voltage falls too low,

TR10 turns off, turning off TR9. TR9 collector is connected to the LH PCB via

connectors CN8-CN7, and the cessation of current drawn indicates low headroom. On

the LH PCB, when this current ceases D12 anode is pulled high by R78, and TR2

turns on, illuminating the decimal points on the meter.

The -17V Supply. (RH PCB)

The actual 17V section of this is identical to that in the +17V section.

The +12V subrail circuitry is much simpler as it only provides power for the driver

TR11, the 723, and the fan. There is no mains meter circuitry here.

The Temperature Protection System.

This is designed to protect the +/-17V rails only. The +48V and +8V regulators

incorporate internal thermal protection, and in any case, their heat dissipation is very

small compared with the heatsink size. The +/-17V rails, however are vulnerable to

blocked cooling vents or fan failure, so protection is provided that shuts down the 17V

rails if the TO3 device cans exceed 100 degC.

The thermal sensor on the RH heatsink is LM35DZ TR31. It outputs 10mV per

degreeC above freezing point (0 degC) and applies it to IC5-B non-inverting input.

IC5-B is used as a comparator, with R114,106 giving a small amount of hysteresis to

prevent dither or oscillation.

IC reference TR29 produces a stable 1.237V which is reduced to 1.00V by R104,112.

This is applied to the inverting inputs of IC5-A,B as the shutdown temperature

reference, and represents 90 degC at the TO3 can top*. TR27 senses the temperature

of the LH heatsink.

* Temperature shutdown takes place at 100 degC on some earlier issue PCB’s.

If either heat sensor exceeds 100 degC the output of the associated op-amp goes high,

applying voltage to the top of R109, and enabling the relaxation LED-flashing

oscillator IC6-B. LED7 flashes at approx 2 Hz.

If JMP2 is fitted in the "ON" position, shutdown of the +/-17V rails is also

implemented. TR30 is turned on via R117, which turns on TR28, and shuts down the

-17V supply. The mutual shutdown system then also shuts down +17V. If JMP2 is in

the "OFF" position, only the LED flashing occurs.

Circuit Description 19

The +48V Supply.

Max current rating is 0.3 Amps. The +48V phantom supply is based on the

high-voltage regulator TL783C. (REG1) The AC input is fused by F4 and fullwave

rectified by BR4; C1,24 are the reservoir capacitors. The unregulated DC may rise as

high as +85V on high mains.

The TL783C maintains a fixed 1.27 V between its ADJ and OUT pins, so the

adjustable voltage-divider R1-PR2-R2 gives an output of approx 48V. This can be

finely adjusted by PR2. The divider current is also used to power the rail indicator

LED3, minimising the current wasted inside the regulator circuit.

An output current of 0.5A and a wide (+10/-20%) mains range means that a TL783C

alone is only marginally capable of handling the power dissipation. Therefore

preregulator TR16,17, working as an emitter-follower biased from the +48V output

by zener DZ5, absorbs some of the voltage drop, so that only approx 62V appears on

the TL783C input. C28 ensures HF stability of REG1.

Two protection diodes are included. D1 protects the regulator from reverse voltage if

there is a charged capacitor across the output but the voltage on C1,24 has collapsed.

D2 prevents the ADJ pin from rising above the OUT pin (due to the charge on C2) if

the output is shorted.

Conventional diode D6 on the output allows supplies to be paralleled for redundancy.

The +8V Supply.

Max current rating 1.25 Amps. This supply is primarily intended for powering console

internal computers; it will be regulated down to +5V inside the console.

The AC input is fused by F4 and fullwave rectified by BR4. The unregulated DC is

about +15V on nominal mains. The LM317T regulator maintains a fixed 1.25V

between its ADJ and OUT pins, so fixed voltage-divider R68,69 gives an output of

approx 8.4 V. C23 reduces output ripple from 1 mV to approx 180 uV at full load.

Two protection diodes are included. D9 protects the regulator from reverse voltage if

there is a charged capacitor across the output but the voltage on C20,21 has collapsed.

D10 prevents the ADJ pin from rising above the OUT pin (due to the charge on C23)

if the output is shorted.

Conventional diode D11 on the output allows supplies to be paralleled for redundancy.

Mains Voltage Select PCB. SC3817

This PCB (SC3817) carries the inrush suppressor and two DPCO switches that select

the transformer primary connections to suit the incoming mains voltage.

The first switch A selects between EUROPE and USA/JAPAN settings. The second

switch B selects high and low variations on this:

Mains Mains Nominal Dropout Dropout

Switch A Switch B Mains Voltage Voltage

20 Circuit Description

Setting Setting Voltage Spec’d Measured

EUROPE 230/115 230 195 186

EUROPE 200/100 200 170 164

USA/JAPN 230/115 115 98 95

USA/JAPN 200/100 100 85 85

Note that the dropout voltages in the rightmost column were measured on a CPS2000,

and are significantly lower than the guaranteed dropout specification of -15%.

Fan Control PCB. SC4032.

Thermostatic fan control was fitted to the CPS2000 from February 1999. The

controller is a separate PCB (SC4032) mounted on the front heatsink bracket, with a

thermal sensor pressed against the top surface of the heatsink.

The CPS2000 fan control system adapts the fan speed to the power drawn. This gives

a substantial reduction in fan noise under almost all circumstances; the exception being

10% high mains and maximum current drawn, which naturally sets the fan to full

speed. The PCB (with associated mounting bracket) may be retrofitted to existing

CPS2000 units.

The servo circuit consists of opamp IC1-A, temperature sensor IC5, shunt regulator

IC4, and fan control devices TR7,TR10.

IC4 maintains 2.50V between its "anode" and "cathode"; this is the precise voltage

that drives the reference chain R53,55. TR8 also uses this voltage to set its emitter at

4.4V above ground; this keeps IC1’s inputs within their common-mode range. Thus

both ends of the voltage divider R53-R55 are fixed at defined voltages.

LM35DZ temperature sensor IC5 outputs 10mV per degreeC above freezing point (0

degC) and applies it to IC1-A non-inverting input. The desired heatsink temperature

is set at the junction of R53,55, which sits at +5.0V approx. This is 600mV above the

+4.4V rail, and so represents 60 degC.

R52,57 set the servo loop gain. This is designed to be safely below the level at which

slow thermal oscillations would occur. R56,D19 increase the loop gain when IC1-A

output is below 4V. This prevents the fan sitting for long periods in a not-quite-running

state where it consumes current but does not rotate. The voltage range 1-4V where

this occurs is thus skipped over quickly.

The fan is driven through feedback amplifier TR7,10, which has a voltage gain of 1.3

times. This allows the fan to be driven over its full operating voltage range despite the

output saturation limits of IC1-A. This gives improved cooling at high temperatures

and mains voltages.

The CPS2000 thermal shutdown system is quite separate and has no connection with

this PCB.

Circuit Description 21

FAULTFINDING NOTES.

SAFETY: These safety notes are directed to those

testing and repairing this power supply. Legal

requirements mean that we must not encourage

untrained personnel to take the lid off.

+/- 17V RAILS.

1) A convenient position for attaching a test meter to 0V is the top leg of bleeder

resistor R9 (top leg of R47 on RH PCB) Remember these resistors run hot.

2) If one side of the +/-17V supply is not working, the mutual shutdown system will

close down both sides of the supply. This makes faultfinding difficult as it is often not

obvious which side has failed. The mutual shutdown can be disabled by putting on

jumpers JMP1 & JMP3 on PCBs at Issue 6 and above.

IT IS ESSENTIAL THAT THESE JUMPERS ARE

REMOVED AFTER SERVICING IS COMPLETED!

FAILURE TO DO THIS MAY CAUSE SEVERE CONSOLE

DAMAGE IF ONLY ONE 17V RAIL SHUTS DOWN.

3) If the wireform connecting the two PCBs is disconnected, the mutual shutdown

will close down both sides of the supply. The Headroom Alarm dots will also show

on the DPM as an active low from the RH PCB is required to suppress them, and this

is now missing.

4) If there is no power to the 723 IC (eg if R11 or R48 is open-circuit) the output will

remain low, but no damage occurs.

5) It is possible to swop over the two 2-pin connections on the LH PCB in error. The

fan will not run, but no circuit damage occurs.

+48V SUPPLY.

1) If TR17 fails short-circuit, the regulator will appear to work, but since all voltage

is dropped across the TL783 regulator, this will overheat and shut down at high

currents. The TL783 should not be damaged if this is the only fault present.

2) If zener DZ5 fails short-circuit, the regulator will not turn on, and there will be

only 300 mV approx at the output.

3) As usual, the unregulated supply to the +48V regulator can reach +90V, and should

be treated with some respect.

+8V SUPPLY.

1) This is a completely standard IC regulator circuit. The regulator REG3 is the only

part that is likely to fail.

2) This supply contains mains voltages on the voltage select PCB, the mains switch,

etc, and the usual precautions must be taken.

3) The main reservoir capacitors have a capacity of one tenth of a Farad, and are

charged to +26V.

22 Circuit Description

THIS IS DANGEROUS.

The danger lies not in the voltage, but in the enormous currents that will flow if the

capacitor terminals are shorted. A small screwdriver will simply disappear in a violent

explosion. The main bodily danger is from metal watchstraps, etc. Serious burns are

very likely if these contact the capacitor.

For safety reasons, the reservoir capacitors are discharged at switchoff by bleeder

resistors R9 and R47; this takes about 30 seconds. Red warning LEDs on the PCB are

ON when the capacitors are charged.

Fuse Replacement

The 32A fuses mounted on either side of the transformer must be replaced with

identical parts only. Soundcraft part number ZD8900.

F1, located on the voltage selector PCB, must be replaced with an identical part.

Soundcraft part number ZD8112.

Circuit Description 23

24 Circuit Description

Parts List

Parts List 25

Spare Parts

Notes:

1) The ‘Module/PCB Assemblies’ section is indented to show those items which are part of another, higher level, item.

2) Some of the descriptions are preceded by one of the following 3 symbols:

# - STATIC SENSITIVE. Anti-static precautions must be taken whilst handling this part.

! - SAFETY CRITICAL PART. A part of a different type may not be substituted.

@ - A part from a specific Manufacturer. Using an equivalent from another manufacturer may lead to loss of performance.

Top-Level Structures

CPS2000 POWER SUPPLY RW8009

Description . . . . . . . . . . . . . . . . . . . . . Part Number

!CPS2000 WIRED TESTED PSU CHAS . . . . . . . . RY8009

!5X20MM T2A/250V AS FUSE . . . . . . . . . . . ZD8102

!5X20MM T10A/250V AS FUSE . . . . . . . . . . ZD8110

!5X20MM T12.5A/250V AS FUSE . . . . . . . . . . ZD8112

!CPS2000 FUSE 32A BS88 . . . . . . . . . . . . ZD8900

CPS2000 USER&TECH GUIDE . . . . . . . . . . ZM0198

26 Parts List

MAIN ASSEMBLIES

! CPS2000 WIRED TESTED PSU CHAS RY8009

Ident . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . Part Number

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80MM FAN FILTER ASSY . . . . . . . . HZ2211

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 PSU CVR PLATE . . . . . . . PB0720-02

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 LID . . . . . . . . . . . PH1402-03

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 FRONT PNL . . . . . . . . PJ1508-04

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 WIRED CHASSIS ASSY . . . . . RS5978

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 TEMP SENSOR WFM. . . . . . . . RV3952

CPS2000 WIRED CHASSIS ASSY RS5978

Ident . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . Part Number

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 PSU TRANS CLAMP PLATE . . . . PF0646-01

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 TX GUARD PLATE . . . . . . PK2563-01

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 LH MODULE ASSY . . . . . . RS5974

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 RH MODULE ASSY . . . . . . RS5975

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 FRONT SUB PNL ASSY . . . . . RS5976

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 CHASSIS ASSY . . . . . . . RS5977

pcb . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 STAR POINT PCB . . . . . . . SC4066-01

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 TX WFM ASSY . . . . . . . . RV3656

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 MNS INLT TO MNS SWT WM. . . . RV3657

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 MNS TO VOL SEL PCB WFM . . . RV3659

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 MAINS METER WFM . . . . . . RV3660

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 LH/RH PCB LINKING WFM . . . . RV3661

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 DC OUTPUT WFM . . . . . . RV3662

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 OV LINK WFM . . . . . . . . RV3663

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 RESERVR CAP TO PCB WFM . . . RV3664

W/Form . . . . . . . . . . . . . . . . . . . . . . . . CHASSIS EARTH WFM 600MM . . . . . RV3695-600

CPS2000 LH MODULE ASSY RS5974

Ident . . . . . . . . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . Part Number

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2WY MTHD .1" FML . . . . . . . . . FF0585

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . PAPST 12V 2.4W 80MM FAN . . . . . . . HD0005

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 EXTRUDED HEATSINK . . . . . PN1260-03

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 PSU PCB ASSY . . . . . . . RI3804 or RJ3804

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30CMX30CM THERMALLY CNDCTV SHT . . ZC0223

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . TO-220 SIL PAD SELF ADHESIVE . . . . . ZC0250

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . SIL PAD 900 .009"THK ADH BACKE . . . . . ZC0251

—- . . . . . . . . . . . . . . . . . . . . . . . . . . . . TO3 INSULATING WASHER . . . . . . . ZC10029

D7 (on SC3804-09) . . . . . . . . . . . . . . . . . DIODE MBR5025L 50A 25V SCK . . . . . . BA0023

D7 (on SC3804-10) . . . . . . . . . . . . . . . . . . . DIODE MBR6045WT. . . . . . . . . . . . . . BA10018

REG1 . . . . . . . . . . . . . . . . . . . . . . . . . VOLTAGE REG TL783CKC . . . . . . . BE0455

REG2 . . . . . . . . . . . . . . . . . . . . . . . . . V.REG LM7805 +5V 1A . . . . . . . . . BE0424

TR4 . . . . . . . . . . . . . . . . . . . . . . . . . . MJ15024 NPN POWER TRANS TO3 . . . . . BD0373

TR5 . . . . . . . . . . . . . . . . . . . . . . . . . . MJ15024 NPN POWER TRANS TO3 . . . . . BD0373

TR6 . . . . . . . . . . . . . . . . . . . . . . . . . . MJ15024 NPN POWER TRANS TO3 . . . . . BD0373

TR7 . . . . . . . . . . . . . . . . . . . . . . . . . . MJ15024 NPN POWER TRANS TO3 . . . . . BD0373

TR8 . . . . . . . . . . . . . . . . . . . . . . . . . . MJL3281A DRIVER TRANSISTOR . . . . . BD0399

TR17 . . . . . . . . . . . . . . . . . . . . . . . . . MJL3281A DRIVER TRANSISTOR . . . . . BD0399

W/Form . . . . . . . . . . . . . . . . . . . . . . . . LINK WFM(FREE ENDS)100MM . . . . . RV4084-100

pcb ass . . . . . . . . . . . . . . . . . . . . . . . . . CPS2000 FAN CONTROL PCB ASSY . . . . RA4032

Parts List 27

CPS2000 RH MODULE ASSY RS5975