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Sansui QRX-7500A both rear channel offset trimmers VR03 and VR04 have no effect

E

etf4doc@aol.

New Member
I am repairing a Sansui QRX-7500A. Relay clicks reliably. Front Left and Front Right channels have good DC offset and trimmers VR01 and VR02 respond normally. However Rear Left is stuck at 138mV and Rear Right is stuck at 477mV. Neither VR03 nor VR04 trimmer has any effect when adjusted full CCW to full CW. All output transistors TR19 TR20 TR23 TR24 test good in diode mode. All small signal transistors good. All fuses good. F-1514 board fully recapped with 11 new capacitors. F1515 board recapped with 24 new capacitors. Has anyone seen this specific problem on a QRX-7500A? any help, or suggestions would be greatly appreciated!

Aloha!
 
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Can you provide a picture of F-1514? I have a QRX-5500A, which shares the service manual with the 7500A, and my driver board (F-1482) has fuse holders in all of the fuse positions. Looking some internet pictures of the 7500A driver board, seems like it should also. Maybe yours was modified somewhere alone the way?
 
Thanks for your reply and you are correct as my Sansui QRX 7500A receiver has the fuses in the clip holder on my F1514 board and are easily accessible and removable. I got it mixed up with the F1515 power and protect board which has them soldered in. I guess too many hours working on this project makes one half brain dead after a while!
Thanks again.
 
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