background image

PRO-SVR_LEGACY    

 

 

Page 6 of 11 

Protection Modes and Indicators

The protection circuit on the DR-8 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 opens 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. 

Summary of Contents for DR-8

Page 1: ...PRO SVR_LEGACY Page 1 of 11 Date August 27 2007 Model Number DR 8 Class Audio Inc Subject Service manual Class Audio Inc 5070 Fran ois Cusson Lachine Qu bec Canada H8T1B3 www classeaudio com...

Page 2: ...ent 8 Calibrations and Adjustments 9 Fuses 10 Voltage Change 10 Schematics 12 The contents of this document as well as the files associated with it contain confidential information that is proprietary...

Page 3: ...t parts please contact your nearest service center always quoting the unit serial number North America Phone 978 664 2870 E mail classe bwgroupusa com Europe Phone 44 0 1903 221 700 E mail classe bwgr...

Page 4: ...PRO SVR_LEGACY Page 4 of 11 Block diagrams...

Page 5: ...o the troubleshooting guide 6 Slowly raise voltage until you hear relays click this point is around 55Vac Recheck every supply 7 If one or more supply are not within specifications return to the troub...

Page 6: ...to make sure the unit is OFF before manipulating the connections When a high DC offset is present at the output the protection circuit opens both output relays even if the condition is only present o...

Page 7: ...Check connexions Check 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...

Page 8: ...e 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 repla...

Page 9: ...ot R16 to get a 14mV reading 5 Let the amplifier warm up for a 24 hours period with signal and load 6 Remove signal and load and reconnect the multimeter setted to mV scale to one of the emitter resis...

Page 10: ...power switch see fig 1 for details 2 Cut group 2 and separate all the wires at the junction where they joined the single wire going to the AC receptacle at the rear of the amplifier 3 With an ohmmete...

Page 11: ...PRO SVR_LEGACY Page 11 of 11 Voltage Change Fig 1 120v AC wiring Fig 2 220v AC wiring...

Page 12: ......

Page 13: ......

Reviews: