Classe-Model70-pwr-sm维修电路原理图.pdf

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1、PRO-SVR_LEGACY Page 1 of 10 Date:August 27, 2007 Model Number: MODEL 70 Class Audio Inc.Subject:Service manual Class Audio, Inc. 5070 Franois Cusson Lachine, Qubec Canada H8T1B3, RadioFans.CN 收音机爱 好者资料库PRO-SVR_LEGACY Page 2 of 10 Table of ContentsIntroduction 3Important Notes on Servicing 3Ordering

2、Replacement Parts 3Block Diagrams 4Start up Procedure 5Protection Modes and Indicators 6Troubleshooting Guide 7Output Transistors Testing and Replacement 8Calibrations and Adjustments 9Fuses 10Voltage Change 10Schematics 11The contents of this document as well as the files associated with it contain

3、 confidential information that is proprietary to Class Audio Incorporated and are intended solely for the purpose of servicing product. No part of its contents may be used, copied, disclosed, or conveyed to any party in any manner whatsoever without prior written permission from Class Audio Incorpor

4、ated. RadioFans.CN 收音机爱 好者资料库PRO-SVR_LEGACY Page 3 of 10 IntroductionPlease read this manual carefully before commencing servicing! Only qualified and authorized personnel should attempt to service this product. The lightning flash with arrowhead symbol, within an equilateral triangle, is intended t

5、o alert the user to the presence of uninsulated dangerous voltage within the products enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons. The exclamation point within an equilateral triangle is intended to alert the user to the presence of important opera

6、ting and maintenance (servicing) instructions. Class has a global product support network. For product assistance or to order replacement parts please contact your nearest service center always quoting the unit serial number. North America Phone: (978) 664-2870 E-mail: EuropePhone: 44 (0) 1903 221 7

7、00 E-mail: AsiaPhone: (852) 2790 8903 E-mail: classebwgroup.hkRest of the World Phone: (514) 636-6384 E-mail: Important Notes on Servicing 1.ALWAYS observe ESD precautions when handling electronic modules or PCBAs. 2.NEVER exchange boards with a different revision number, unless authorized by Class.

8、 3.ALWAYS use Class original replacement parts. The use of generic parts may void the warranty of the unit. Ordering Replacement Parts There may be a delay in processing incomplete requests. Please be sure to include all required information. Remember to quote the serial number of the unit on all re

9、placement part orders and the Class order number when returning defective parts for credit. PRO-SVR_LEGACY Page 4 of 10 Block diagramsPRO-SVR_LEGACY Page 5 of 10 Start Up ProcedureWhen receiving a unit, an assiduous visual inspection must be performed. Do not connect the unit without analysing the s

10、ymptoms reported by the customer and the results of the inspection. Using the troubleshooting guide, find the problem and proceed to the repair. Once this step is done, follow these steps, known as the start-up procedure, to ensure that everything in the unit is in working condition. 1. Proceed with

11、 a post repair visual inspection. Take the time to check if every wire is reconnected properly, every screw is bolted on, no soldering and/or metal residues lying in the unit, every fuse has been replaced, etc. 2. Connect the unit to a variable transformer, setted to 0Vac. 3. Turn the bias trimpot (

12、R13) counter clockwise until a click is heard. 4. Slowly raise the voltage to 10Vac, and check positive and negative rails and pre-driver supply. Check fuses.5. If one or more supply are not within specifications, return to the troubleshooting guide. 6. Slowly raise voltage until you hear relays cli

13、ck, this point is around 55Vac. Recheck every supply. 7. If one or more supply are not within specifications, return to the troubleshooting guide. 8. Raise voltage to 120Vac. Recheck every supply 9. Report to Calibration and adjusments to adjust bias and DC offset. Note that bias can be adjusted to

14、14mV, and the following tests can be performed before the unit is send to the burn-in bench for a 24 hours warm-up. 10. Connect the unit to a load, and to a source using balanced inputs and single ended inputs, independently. 11. Perform a test with a 200Hz, a 2kHz and a 20kHz tone, both sinus wave

15、and square wave. Check the output with a oscilloscope, on 4 ohms and 8 ohms loads. Take special cares about oscillation and phase correlation between channels. 12. Connect the unit to a small speaker, and short the input. Check for any noise. Perform this step with single ended inputs and balanced i

16、nputs, independently. 13. Put the unit on a burn-in bench, and let it sit for 24 hours, then readjust bias. Let the unit on the burn-in bench for another 72 hours. 14. Redo steps 10 to 13 before shipping to the customer. PRO-SVR_LEGACY Page 6 of 10 Protection Modes and IndicatorsThe protection circu

17、it on the MODEL 70 is triggered by a high DC offset condition. This is the only protection available on this unit. Therefore, extra precautions should be taken to make sure the unit is OFF before manipulating the connections. When a high DC offset is present at the output, the protection circuit ope

18、ns both output relays, even if the condition is only present on one channel. If the relays are intermittently clicking, DC offset should be monitored for a long period of time, to make sure DC offset caused that condition, and not the protection circuit itself that is running out of specifications.

19、PRO-SVR_LEGACY Page 7 of 10 Troubleshooting GuideSymptom Possible cause Unit won t turn on Check connections; Check fuses; Check soft-start circuit; Check relays; Check power supply circuits (positive rail, negative rail, Mosfet supply). Smoked and/or burned components Check for short between compon

20、ents and ground; Check output transistors; Check output relays; Check power supply circuits (positive rail, negative rail, Mosfet supply). Blown fuses Check for short between fuse and ground; Check power supply circuits (positive rail, negative rail, Mosfet supply). No output Check connexions; Check

21、 output relays; Check power supply circuits (positive rail, negative rail, Mosfet supply);Check output transistors. Unit turn into protection Check for smoked and/or burned components; Check power supply circuits (positive rail, negative rail, Mosfet supply);Check source and load; Check protection c

22、ircuit; Check sensor wires between sensor PCB and control PCB; Check outputs transistors and Mosfet drivers. Excessive buzz and/or hum Check electrical lines; Check for a ground loop in the system. Oscillation Check source; Check capacitors on main board; Check 4.7? resistor. Intermittent signal Che

23、ck connections; Replace shield wires. Intermittent / fast output relay clickCheck DC offset before relays; Check relays; Check capacitors on protection circuit. PRO-SVR_LEGACY Page 8 of 10 Output Transistors Testing and ReplacementPLEASE NOTE THAT THESE TESTS ARE ONLY EFFECTIVE ON BIPOLAR TRANSISTOR

24、S. DO NOT PERFORM THESE TESTS ON MOSFET DEVICES, AS THEY ARE LIKELY TO BECOME SHORT DURING THE TEST.You should check all pin combinaisons, as there is a chance that only one side of the transistor is short. When replacing outputs transistors, the technician should first disconnect both outputs and m

25、ain board to check if the blown outputs were caused by a faulty component on the amplifier s base. Blown output transistors should be replaced by kits, not individually. These kits contains matched transistors for both rails of one channel. When replacing blown output transistors, you must also repl

26、ace positive and negative Mosfet drivers and bias transistor. Carefully inspect 4.7? resistor and 10? soft start resistor, and replace if necessary. Replace any burnt component or board. Pins : 1 Base 2 Collector 3 Emitter You should have these results, if the transistor is good. 2SC3281 / 2SC4029 /

27、 2SC3263 / MJL21194 (NPN) Positive lead Negative lead Result B C Conductive B E Conductive C B Infinite C E Infinite E B Infinite E C Infinite 2SA1302 / 2SA1553 / 2SA1294 / MJL21193 (PNP) Positive lead Negative lead Result B C Infinite B E Infinite C B Conductive C E Infinite E B Conductive E C Infi

28、nite PRO-SVR_LEGACY Page 9 of 10 Calibrations and AdjustmentsBias adjustment: Note: Bias adjustment should be made without any load connected to the amplifier s output, and no signal connected to the amplifier s input. 1. Connect a multimeter to one of the emitter resistor leads and set the multimet

29、er to mV scale. 2. Turn trimpot R13 counterclockwise until it reaches 0?. A click should be heard. 3. Turn on amplifier, and let it warm up for 15 minutes on idle. 4. Adjust trimpot R13 to get a 14mV reading. 5. Let the amplifier warm up for a 24 hours period with signal and load. 6. Remove signal a

30、nd load, and reconnect the multimeter, setted to mV scale, to one of the emitter resistor leads. 7. Readjust R13 to 21mV DC offset: Note: DC offset adjustment should be made without any load connected to the amplifier s output, and no signal connected to the amplifier s input. 1. Connect a multimete

31、r to the output binding posts and set the multimeter to mV scale. 2. Adjust trimpot R5 in order to reach 0mV. It is easier to turn the trimpot turn at a time, and let DC offset stabilize in order to get an accurate reading. 3. A tolerance of 1mV is acceptable. PRO-SVR_LEGACY Page 10 of 10 FusesEXTRA

32、 PRECAUTIONS SHOULD BE TAKEN WHEN REPAIRING, MODIFYING,ORTROUBLESHOOTING IN THE POWER SUPPLY AREA. UNIT MUST BE DISCONNECTFROM MAIN SOURCE AND CAPACITORS MUST BE DISCHARGED USING A 100W INCANDESCENT BULB. WHEN REPLACING FUSES, PLEASE MAKE SURE THAT THE FUSE HOLDERS ARE HOLDING THE FUSES VERY TIGHTLY

33、. A LOOSE FUSE HOLDER CAN TRANSLATE INTO DISTORTION ON TOP OF THE SIGNAL. Main fuses: For 100 120v units: 5A slo-blo, Classe part number MDL-5A For 220 240v units: 4A slo-blo, Classe part number MDL-4A The main fuse is located at the back of the unit, on the rear panel. Voltage ChangeEXTRA PRECAUTIO

34、NS SHOULD BE TAKEN WHEN REPAIRING, MODIFYING,ORTROUBLESHOOTING IN THE POWER SUPPLY AREA. UNIT MUST BE DISCONNECTFROM MAIN SOURCE AND CAPACITORS MUST BE DISCHARGED USING A 100W INCANDESCENT BULB. 1. Set the jumper position according to the table below. 2. Replace the varistor, according to new line voltage, following Classe s recommendations. If varistor is not available, remove old varistor and leave it empty. Jumper positions, main transformer Mains Jumper 1 Jumper 2 Jumper 3 Varistor 100VAC A E F 221 120VAC C D F 221 220VAC B E - 391 / 441 240VAC B D - 391 / 441