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1、PRO-SVR_LEGACY Page 1 of 13 Date: August 20, 2007 Model Number: CAV-75 Class Audio Inc. Subject: Service manual Class Audio, Inc. 5070 Franois Cusson Lachine, Qubec Canada H8T1B3, RadioFans.CN PRO-SVR_LEGACY Page 2 of 13 Table of Contents Introduction 3 Important Notes on Servicing 3 Ordering Replac
2、ement Parts 3 Block Diagrams 4 Start up Procedure 5 Protection Modes and Indicators 6 Troubleshooting Guide 7 Output Transistors Testing and Replacement 8 Calibrations and Adjustments 9 Parts List 10 Updates 11 Fuses 12 Voltage Change 12 Remote Interface Information 13 Schematics 14 The contents of
3、this document as well as the files associated with it contain 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 whatsoev
4、er without prior written permission from Class Audio Incorporated. RadioFans.CN PRO-SVR_LEGACY Page 3 of 13 Introduction Please read this manual carefully before commencing servicing! Only qualified and authorized personnel should attempt to service this product. The lightning flash with arrowhead s
5、ymbol, within an equilateral triangle, is intended to 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
6、to alert the user to the presence of important operating 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: (
7、978) 664-2870 E-mail: Europe Phone: 44 (0) 1903 221 700 E-mail: Asia Phone: (852) 2790 8903 E-mail: classebwgroup.hk Rest 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
8、 different revision number, unless authorized by Class. 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. Re
9、member to quote the serial number of the unit on all replacement part orders and the Class order number when returning defective parts for credit. RadioFans.CN PRO-SVR_LEGACY Page 4 of 13 Block diagrams RadioFans.CN PRO-SVR_LEGACY Page 5 of 13 Start Up Procedure When receiving a unit, an assiduous v
10、isual inspection must be performed. Do not connect the unit without analysing the symptoms 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 proced
11、ure, to ensure that everything in the unit is in working condition. 1. Proceed with 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. Tur
12、n the bias trimpots, counter clockwise for channels 2, 4, 6 and clockwise for channels 1, 3, 5, until a click is heard. 3. Since there is no soft-start sequence of the CAV-75, it is impossible to us a bypass to perform a slow start up. 4. Connect Main supply, and turn on the unit. 5. If one or more
13、supply are not within specifications, return to the troubleshooting guide. 6. If every supply is within specifications, report to calibration and adjusments to adjust bias and DC offset. Note that bias can be adjusted to 14mV, and the following tests can be performed before the unit is send to the b
14、urn-in bench for a 24 hours warm-up. 7. Connect the unit to a load, and to a source using single ended inputs. 8. Perform a test with a 200Hz, a 2kHz and a 20kHz tone, both sinus wave and square wave. Check the output with a oscilloscope, on 4 ohms and 8 ohms loads. Take special cares about oscillat
15、ion and phase correlation between channels. 9. Connect the unit to a small speaker, and short the input. Check for any noise. 10. 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. 11. Redo steps 7 to 11 before s
16、hipping to the customer. RadioFans.CN PRO-SVR_LEGACY Page 6 of 13 Protection Modes and Indicators The front LED shows the status of the amplifier (ON or OFF). Unlike other Class amplifiers, when starting up a CAV75, the front LED will not show a flashing pattern, since there is no soft start sequenc
17、e. The only protection available on a CAV75 consists of rail and mosfet fuses. If there is a fault, one or more fuses will blow, showing a faulty component. The technician will first need to identify and cure the cause of failure (please report to troubleshooting guide). When the cause has been iden
18、tified, disconnect the unit from the system including the AC power. Remove the top cover and look for damaged or burned components. If no other components than the fuses appear to be damaged, the technician can then replace the broken fuses with the same value and rating (please report to fuses sect
19、ion). The fuses are located on the capacitor board. When replacing fuses, please make sure that the fuse holder are holding the fuses very tightly. A loose fuse holder can translate into distortion on top of the signal. RadioFans.CN PRO-SVR_LEGACY Page 7 of 13 Troubleshooting Guide Symptom Possible
20、cause Unit won t turn on Check connections; Check fuses; Check relays; Check power supply circuits (positive rail, negative rail, Mosfet supply). Smoked and/or burned components Check for short between components and ground; Check output transistors; Check output relays; Check power supply circuits
21、(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 output relays; Check power supply circuits (positive rail, negative rail, Mosfet supply); C
22、heck 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 circuit; Check sensor wires between sensor PCB and control PCB; Check outputs transistors a
23、nd 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 Check connections; Replace shield wires. RadioFans.CN PRO-SVR_LEGACY Page 8 of 13 Output Tran
24、sistors Testing and Replacement PLEASE NOTE THAT THESE TESTS ARE ONLY EFFECTIVE ON BIPOLAR TRANSISTORS. 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 i
25、s short. When replacing outputs transistors, the technician should first disconnect both outputs and main 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
26、transistors for both rails of one channel. When replacing blown output transistors, you must also replace positive and negative Mosfet drivers and bias transistor. Carefully inspect 4.7? resistor and replace if necessary. Replace any burnt component or board. Pins : 1 Base 2 Collector 3 Emitter You
27、should have these results, if the transistor is good. 2SC3263 (NPN) Positive lead Negative lead Result B C Conductive B E Conductive C B Infinite C E Infinite E B Infinite E C Infinite 2SA1294 (PNP) Positive lead Negative lead Result B C Infinite B E Infinite C B Conductive C E Infinite E B Conducti
28、ve E C Infinite RadioFans.CN PRO-SVR_LEGACY Page 9 of 13 Calibrations and Adjustments Bias 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. Since it is impossible to connect a multimeter to bot
29、h emitter s resistors in order to measure and adjust bias without disassembling the heatsink from the chassis, we provided a test point to ease the bias procedure. It is located near the bias trimpot. 2. Connect the positive probe of a millivoltmeter to the test point and the negative probe to the p
30、ositive speaker post of the channel to be adjusted. 3. Turn channel 2, 4, 6 trimpots counterclockwise and channel 1, 3, 5 trimpots clockwise until it reaches 0?. A click should be heard. 4. Turn on amplifier, and let it warm up for 15 minutes on idle. 5. Adjust trimpot to get a 14mV reading. 6. Let
31、the amplifier warm up for a 24 hours period with signal and load. 7. Remove signal and load, and reconnect the multimeter. 8. Readjust to 20mV. 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.
32、 On these units, DC offset can t be adjusted. Measure DC offset using a voltmeter connected to the output posts, scale setted to mV. DC offset should be less than 10mV. RadioFans.CN PRO-SVR_LEGACY Page 10 of 13 Parts List This is not a detailed part list. It is a list of major chassis parts and PCBs
33、. If you need to order a specific part, please contact Classe Audio with the part location, PCB number, and model and serial number of the unit. If you need a complete PCB, please replace the (x) in the Classe part number with the revision number printed on the board. Parts Description Classe part n
34、umber B01CX Complete PCB, power switch B01CXR(x) B01GX Complete PCB, filter B01GXR(x) B0D3X Complete PCB, capacitor B0D3XR(x) B0D1X Complete PCB, heatsink B0D1XR(x) B0D4X Complete PCB, supply B0D4XR(x) B0D2X Complete PCB, amplifier B0D2XR(x) B01DX Complete PCB, remote B01DXR(x) RadioFans.CN PRO-SVR_
35、LEGACY Page 11 of 13 Updates 1. On board B0D1X (3 PCBs), replace R110 and R210 with Classe part number A211-1308. RadioFans.CN PRO-SVR_LEGACY Page 12 of 13 Fuses EXTRA PRECAUTIONS SHOULD BE TAKEN WHEN REPAIRING, MODIFYING, OR TROUBLESHOOTING IN THE POWER SUPPLY AREA. UNIT MUST BE DISCONNECT FROM MAI
36、N 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. A LOOSE FUSE HOLDER CAN TRANSLATE INTO DISTORTION ON TOP OF THE SIGNAL. Main fuses: For 100 120v units: 6A slo-blo, Classe part
37、number MDL-6A 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. Control board fuse: 0.50A, Classe part number 225.500 The control board fuse is located on top of the supply board (B0D4X) Mosfet fuses: 0.75A, Classe part num
38、ber 225.750 The Mosfet fuses are located on top of the capacitors board (B0D3X) Rail fuses: 3.15A, Classe part number GDB-3.15A The rail fuses are located on top of the capacitors board (B0D3X) Voltage Change EXTRA PRECAUTIONS SHOULD BE TAKEN WHEN REPAIRING, MODIFYING,OR TROUBLESHOOTING IN THE POWER
39、 SUPPLY AREA. UNIT MUST BE DISCONNECT FROM 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,
40、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 A C D 221 220VAC B E - 391 / 441 240VAC B D - 391 / 441 Jumpers, auxiliary transformer Mains Position 1 Position 2 Position 3 Position 4 Position 5 100/120VAC
41、In Out Out Out In 220/240VAC Out Out In Out Out RadioFans.CN PRO-SVR_LEGACY Page 13 of 13 Remote Interface Information The CAV75 can be turned on or off using an simple interface connected to the Remote jack, located at the back of the unit. RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN RadioFans.CN
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