SoundCraft CPS275 Power Supply User Manual
Contents
1.2. 2 43 angvsia aw I 1 TIVA iLOH e zx 249 w3 N aans d 0 iz Se 463 D icu COA 162 9245 ABr A vuo 2 95 sid dde ac AH3 DIA Lu lt NHS 1 N a va Ax c din a Ba 88 a puu gt d D p Dp 2 Adi nna nna NHS g d 5 a il An NMOCLNHS 2 pn le 1 i o D 8 N z 39 7 AF Sn E2 lt zx E 2 2 E y 8 1 UR d i t 5 32 zwy IHY Technical Description 20 Output Pinouts Wire List SRC Voltage Wire Colour PIN 1 17 VDC BROWN PIN 2 45V DC WHITE PIN 3 17 V DC BLUE PIN 4 Chassis Earth YEL PIN 5 OV 17V amp 48V GREE PIN 7 OV 5V GREY PIN 10 4 48 V DC ORANGE REAR VIEW OF SRC VIEWED FROM INSIDE PSU V PART No RV3670 Technical Description 21 22 Technical Description
3. 1 5 lt 1 E SN non Sena H3WNHOJSNVHL SNIVN i 91 3SN ASI 35 ABEZ anqva asnd LE xd LE xd LE 2 46 i2 soua aa 31vad anssi 8 ON Sua Technical Description Circuit Description The CPS250 and CPS275 power supplies provide 17V at 4 Amps and 5 25 Amps respectively Both give 5V at 1 Amp and 48V at 0 3 Amp is SC3803 THE 17V RAILS This consists of two identical 17V supplies connected together to give 17V Each 17V supply is a linear regulator with conventional fullwave rectification and 20 000uF reservoir capacitors This is combined with a second power supply that sits on top to power the driver transistors and the control IC this reduces the minimum voltage drop across the series pass device and so improves efficiency The main series pass element is a 250W discrete bipolar transistor mounted on a fan cooled heatsink The voltage reference and servo control amplifier are provided by a 723 regulator IC The circuitry of the 17V regulator is described in detail below The 17V Supply The transformer secondary is fused by F1 Secondary fuses will normally only blow in the event of serious failure such as a major short in the AC wiring or a failed bridge rectifier The fullwave bridge rectifier is mounted on the heatsink at the hottest end as it is t
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5. 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 CPS250 CPS275 unit Forced convection by means of a fan tray may be desirable in this situation The CPS250 CPS275 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 The air intake and outflow holes 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 Finally some consideration should be given to the earthing arrangement of the system at the centre of which are the console and the CPS250 CPS275 and any other Soundcraft power supply units The console chassis is earthed through the mains earth viathe power supply When rack mounting the CPS250 CPS275 and any other Soundcraft power supply units care should be taken to avoid any possible
6. This unit is capable of operating over a range of mains voltages by means of a 4 position mains input fuse carrier It is important to ensure that the correct voltage setting is selected for the level of local mains voltage supply for safe uninterrupted operation of the unit Voltage selection is achieved by positioning the fuse carrier so that the required voltage appears next to the arrow which is moulded in the connector In this way the unit is set up for operation at one of the following ranges of mains supply NOMINAL VOLTAGE OPERATING VOLTAGE RANGE 10 15 Vrms AC Vrms AC 230 196 253 115 98 126 100 85 110 85 73 93 To remove the fuse use a small screwdriver to prise the fuse carrier from its location in the connector To avoid risk of fire use the correct value fuse as indicated on the unit REPLACING MAINS FUSE Switch the ON OFF switch to the OFF position Remove the mains lead from the connector Use a small screwdriver to prise the fuse carrier from its location in the connector 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 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 1 Soundcraft is a tr
7. 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 Installation Installation 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 WARNING THIS APPARATUS MUST BE EARTHED Under no circumstances should the mains earth be disconnected from the CPS250 CPS275 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 CPS250 CPS275 in a flight case to provide mechanical protection Refer to your Soundcraft dealer for a suitable case Where the CPS250 CPS275 is enclosed in a touring case provision must be made for adequate ventilation t
8. SOUNDCRAFT CPS250 CPS275 Console Power Supply User and Technical Manual For your own safety and to avoid invalidation of the warranty all text marked with these Warning Symbols should be read carefully Pr IMPORTANT please read this manual carefully before connecting your Soundcraft console power supply to the mains for the first time Soundcraft This equipment complies with the EMC Directive 89 336 EEC and LVD 73 23 EEC and 93 68 EEC For further details contact Harman International Industries Ltd Cranborne House Cranborne Road Potters Bar Hertfordshire EN 3JN Tel 44 0 1707 665000 Fox 44 0 1707 660482 Harman International Industries Ltd 1997 All rights reserved Parts of the design of this product may be protected by worldwide patents Part No ZM0195 Issue 3 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 photocopyi
9. Carefully lift the cover to avoid the earth connecting lead to the cover from snagging Place the cover face down behind the unit WARNING At the front of the unit just behind the front panel is the MAINS SWITCH which carries HIGH VOLTAGES directly from the mains input Similarly on the rear panel is the MAINS INPUT SOCKET MAINS VOLTAGE SELECTOR Care MUST be taken when carrying out any servicing operation with the top cover removed Technical Description 17 FAULTFINDING NOTES 17V RAILS 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 linking pins 4 and 5 on BOTH opto isolators IT IS ESSENTIAL THAT THIS IS REMOVED AFTER SERVICING IS COMPLETED FAILURE TO DO THIS MAY CAUSE SEVERE CONSOLE DAMAGE IF ONLY ONE 17V RAIL SHUTS DOWN If there is no power to the 723 IC eg if R1 or R2 is open circuit the output will remain low but no damage occurs 8V SUPPLY This is a completely standard IC regulator circuit The regulator REG3 is the only part that 15 likely to fail REPLACING COMPONENTS Replacement of any components should be undertaken only after switching the power supply unit OFF and disconnecting the mains supply lead from the power supply unit Replacement of any of the fuses in the power supply units is pos
10. 17V supplies are working normally DZ1 DZ2 are conducting LEDI is on and opto couplers 1 2 have their photo transistors conducting Therefore 5 does not conduct and the supply works normally If the 17V rail collapses there is no longer enough voltage to keep DZ1 DZ2 on and OPI switches off TR5 is turned on by R16 with R28 30 and C40 providing a time delay to prevent spurious operation on transients or brief overloads which are dealt with by the constant current protection system TR5 now pulls down an internal node of ICI via pin 13 and the 17V supply is shut down In the same way if the 17V supply fails OP2 switches off TR6 is turned on by R17 and the 17V supply is shut down The 17V Supply This is identical in operation to the 17V section described above The 48V Supply Max current rating is 0 3 Amps The 48V phantom supply is based on the special high voltage regulator TL783C REGI The AC input is fused by F3 and fullwave rectified by D15 18 C31 is the reservoir capacitor C32 ensures HF stability of REGI The TL783C maintains a fixed 1 27 V between its ADJ and OUT pins so the adjustable voltage divider R22 PR3 R23 gives an output of approx 48V This can be finely adjusted by PR3 C33 minimises output ripple Rail indicator LED2 is powered through DZ3 4 which total 30V so even a partial fall in rail voltage will extinguish 1t Two protection diodes are included D13 protects the regulator from rever
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13. ading 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 Ifwithin the period of twelve months 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 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 replaceme
14. he most heat tolerant of the semiconductors For safety reasons the reservoir capacitor is discharged by bleeder resistors R39 40 at switchoff this takes about 10 seconds The unregulated DC voltage is approx 26 to 29 The 723 IC contains a 7 15V nominal Zener diode defining the voltage that appears at Pin 6 R5 is in series with the positive input of the servo opamp Pin 5 and is made roughly equal in resistance to the feedback divider R7 11 etc to minimise bias current offsets The feedback divider R7 8 11 amp 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 The output of the servo opamp controls the output through TR1 an emitter follower driving the series pass device The power supply to TR1 is taken from the 12V supply developed across C23 This has its OV 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 via This subrail markedly reduces the minimum drop across the pass elements and therefore increases the efficiency 10 Amp Schottky diode D25 on the output allows supplies to be paralleled for redundancy This is only fitted for the CPS275 option Overcurren
15. he danger lies not in the voltage but in the large 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 by bleeder resistors at switchoff this takes about 10 seconds The unregulated supply to the 48V regulator can reach 90V on high mains and should be treated with some respect Initial operational tests on the power supply can be carried out by switching the unit ON and checking the voltages present on the output connectors on the back of the unit While the unit remains disconnected from the mixing console some of the DC voltage rails are floating with respect to each other that is they do not all have a common reference within the unit When connection is made to the mixing console various output pins become earthed to a common star point which has a mains earth return in the power supply cable itself An indication of obvious fault condition is the failure of one or more of the front panel LED s to light Any fault condition with the exception of simple mains fuse failure due to underrating or an unusual mains input condition will require removal of the top cover to enable fault correction This is achieved using a cross head screwdriver to remove the six retaining screws and washers
16. l voltage and current measurements are to be taken at the console end of the power supply cable OPERATING TEMPERATURE RANGE Ambient 10 TO 40 HUMIDITY Similar unit tested at 0 90 RH non condensing 5 Relative Humidity at 40 for 16 hours Load switched between 20 and 100 at regular 30 minute intervals OVERALL DIMENSIONS HEIGHT exc feet 88 10mm 2U WIDTH Chassis 427 56mm Front panel 482 60mm DEPTH excl connectors 350 50mm WEIGHT Excl packing 11Kg 10 Technical Specification Technical Description Servicing should only be carried out by a competent service engineer SEE THE WARNINGS STARTING ON PAGE 17 Technical Description 11 Technical Description Zo ues E BE v EZG 629 6v Sv Ov GE GCH ON SLIOA ayol NO 4 01 0 H108
17. ng 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 Soundcraft Harman International Industries Ltd Cranborne House Cranborne Industrial Estate Cranborne Road Potters Bar Herts EN6 3JN England Tel 01707 665000 Fax 01707 660482 Table of Contents Introduction Introduction Short circuit Protection Mains Voltage Selection Replacing Mains Fuse A IN Warranty Recommendations For Installation Recommendations For Installation General Dimensions PSU Linking CPS275 Only 0 IN O Technical Specification 9 Technical Description 11 Circuit Diagram 1 12 Circuit Diagram 2 13 Circuit Description 14 Servicing 17 PCB Layout 20 Output Pinouts 21 Parts List 23 Introduction Introduction Introduction WARNING THIS APPARATUS MUST BE EARTHED The CPS250 CPS275 are linear power supplies which like other linear supplies produce 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 le
18. nt 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 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 Introduction Recommendations For Installation FOR UK USERS ONLY IMPORTANT WARNING THIS APPLIANCE MUST BE EARTHED The wires in the mains lead are coloured in accordance with the following code Green and Yellow Earth Blue Neutral Brown Live 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 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 wire which is coloured Blue m
19. o the rear of the unit to ensure unrestricted supply of air for the cooling fan Use only the high current mains lead supplied not the more common 5A type supplied with other equipment PSU Linking CPS275 Only The output voltages from the CPS275 are fed via diodes as shown in the adjacent diagram This allows a standby CPS275 to automatically takeover in the event of a power rail failing Link When a spare CPS275 is ordered it comes with a 1 metre linking cable This should be connected between the link Console connectors as shown in the diagram Only one rail shown Standby CPS275 Link e Console Only one rail shown Main CPS275 To Console EN e 350 50mm 9 Y P 482 60mm gt P 427 56mm m 595mm 88 10mm 5 95mm M L ud 9 52mm 8 Installation Technical Specification Technical Specification Technical Specification MAINS INPUT VOLTAGE RANGE 85 100 115 230 10 15 50 60Hz RATED INPUT POWER Max CPS250 350 WATTS CPS275 450 WATTS MAINS FUSE RATING Use T3 15A 250V slow blow for 230V Use T6 3A 250V slow blow for 85 100 115V OUTPUTS DC VOLTAGE RAIL MAX OUTPUT CURRENT CPS250 CPS275 17 5V 4 00 AMPS 5 25 AMPS 17 5V 4 00 AMPS 5 25 AMPS 5V 1 00 AMPS 1 00 AMPS 48V 0 30 AMPS 0 30 AMPS D Al
20. rocedure above Particular care should be taken when fixing the regulators ensuring that the pins are not bent or the circuit board pads strained when the fixing screws are tightened The regulator screws are tapped into a relatively soft aluminium heatsink DO NOT OVER TIGHTEN or you will strip the thread in the heatsink High performance mounting pads must be fitted between the regulators and the heatsink The regulators must be checked for isolation from the heatsink using a multimeter Re dress cable forms in their original positions and secure where applicable with cable ties OUTPUT VOLTAGE ADJUSTMENTS The 17V and 48V rails are adjustable via trimpots on the pcb After any repair these should be checked on load and adjusted if necessary Set the 17V rails to 17 5 V 0 1V and the 48V rail to 48 3 0 1V The 5V rail is not adjustable GENERAL Before replacing the top cover on the unit carefully remove any dust from surfaces within the unit Carefully check all wiring connections and ensure that there are no loose parts lying around inside the unit Technical Description 19 Y gt 1 co lt x M li 1 95 ids XI4 15425 2 AWS Fic 4k eaan nh 2437 k ea d e23 dE oF 18H i LO a 445 o Q r am c 2 a 2 4h 4b za
21. se voltage if there is a charged capacitor across the output but the voltage on C31 has collapsed D20 prevents the ADJ pin from rising above the OUT pin due to the charge on C33 if the output is shorted Diode D22 on the output CPS275 only allows supplies to be paralleled for redundancy Technical Description 15 The 5V Supply Max current rating 1 0 Amps This supply is primarily intended for powering console internal computers it also powers the cooling fan The AC input is fused by and fullwave rectified by D9 12 with C36 as the reservoir capacitor The LM340 regulator has a fixed 5 0V output C35 ensures regulator stability A protection diode is included D14 protects the regulator from reverse voltage if there is a charged capacitor across the output but the voltage on C36 has collapsed Diode D23 on the output CPS275 only allows supplies to be paralleled for redundancy 16 Technical Description 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 Servicing should only be carried out by a competent service engineer This supply contains mains voltages on the voltage select PCB the mains switch etc and the usual precautions must be taken The main reservoir capacitors have a capacity of 20 000 uF and are charged to 26V THIS CAN BE DANGEROUS T
22. sible without the removal of the circuit board The fuses are held in open fuseholders on the top of the board These can be carefully removed by hand Ensure that the insulating fuse covers are replaced with the new fuses Various components are mounted along the heatsink extrusion The extrusion pcb assembly must be removed from the case to gain access to the underside of the pcb in order to unsolder and or undo the appropriate component They can be removed by desoldering the pins where appropriate and unscrewing the fixing nuts or the fixing Screws taking care to retain the small insulating bush es Retain carefully the mounting pads and plastic insulating bushes where fitted THESE MUST BE CORRECTLY REFITTED TO AVOID DAMAGE TO THE UNIT The correct high efficiency mounting pad must be used and this should be replaced if it appears to be damaged see the Parts Lists for the relevant Soundcraft Part Numbers When refixing or replacing the device it is important to screw the device down before resoldering the pins to avoid stressing the pads on the circuit board NOTE The heatsink bracket is earthed through its mechanical contact with the rest of the chassis and so a faulty mounting pad may cause the output of its regulator to be connected to earth Take care not to bend the pins on the regulators or to strain the corresponding pads on the circuit board 18 Technical Description Reassembly is simply a reverse of the p
23. t Protection The power supply is protected against short circuits and overload by a dual mode protection system brief overloads are dealt with by constant current protection while prolonged overload causes both 17V rails to shutdown Reset is by turning the mains power off for not less than 6 seconds 14 Technical Description The constant current protection system works in the standard way 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 However the high current capability of this PSU means that long term 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 time they will overheat The constant current system measures the output current by sensing the voltage drop across resistors R18 19 in parallel When it reaches approx 0 60 V the internal protection transistor in is turned via R41 and the output voltage on pin 10 pulled down to limit the current supplied If this condition persists for longer than one second then both rails of the 17V supply are shut down by the Mutual Shutdown System described below 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
24. ust be connected to the terminal in the plug which is marked with the letter N or coloured Black e wire which is coloured Brown must be connected to the terminal in the plug which is marked with the letter L or coloured Red Installation Recommendations for Installation The CPS250 CPS275 power supply is provided with front panel fixing holes for 19 rack mounting and will occupy 2U of rack space 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 7 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 CPS250 CPS275 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 rear of the unit and expelled through the front panel
25. vels in their operation and these are all provided at the output of each supply unit The CPS275 provides higher currents than the CPS250 The CPS275 also has the capability of being linked to a second CPS275 to provide automatic power backup in the event of one of the units failing In regulating these voltages there is considerable heat generated the dissipation of which is achieved through a substantial internal heat sink A fan is incorporated which draws air over the heatsinks to provide adequate heat dissipation for the regulators and reduce the outer case temperature The CPS250 CPS275 is designed for installation in a 19 rack unit occupying 2U of rack height Refer to the section RECOMMENDATIONS FOR INSTALLATION on Page 5 LED indication is provided on the front panel to show operation of the regulating circuits SHORT CIRCUIT PROTECTION The 17V rails can withstand a short to ground or each other for up to one second if the short circuit remains for longer than one second then both of the 17V rails will be shut down To reset them the supply must be switched off for 6 seconds and then switched on again The 5V and 48V are current limited and will self recover when any short circuit is removed Introduction Introduction 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
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