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Duff motorised volume control

matt j

pfm Member
Just had a quick look at this as the remote volume isn't working, it's sending a signal and I get 4.5-4.8v at the motor input so I assume the motor is kaput?

Any way to identify it and should it be fairly straight forward to swap? I have the service manual but I can only see what I think is a JVC internal part number so pretty useless, it looks very similar to the ebay link below.

Pics (click to zoom)






Ebay link

http://rover.ebay.com/rover/1/710-5...0001&campid=5338728743&icep_item=132076499443
 
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I used one of these from Rapid some years ago to replace a dud motorised volume pot on a NAC82, simple job and worked fine ever since.

Prior to that I had a similar problem with it and found the cure (for a while at least) was to re-solder the connections from control board to motor brush holders, vibration from the motor (presumably) had caused "solder fatigue" on some of the joints giving the effect of a dry joint. Some of the soldered joints in your photos don't look too great.
 
Just found my 2013 post on this by Googling "Volume pot on NAC82 no longer responds to remote", part of a shortish thread:-

I'm a bit late to this thread but I've just found the cause of the same problems on my 82 that Johnny Blue complained of. I measured the voltage on the pot motor connections on the pots pcb (if you look down the back of the pcb you can see the pot motors and follow their brush holders via what look like wirewound resistors to their correspondig pads on the pcb). The balance pot (working ok) regisered 6.2 volts but the inoperative volume pot measured 7.5 v so I surmised the volume pot motor was open circuit - at least the logic circuit was ok! At that point my meter probes slipped out of place and, when I re-applied them to confirm the voltage it measured 6.2 and the pot was turning! All I'd done was pushed the meter probes across the soldered joints. I took this to be a sign of "solder fatigue" where, due perhaps to vibration, a crack appears in the solder joint which eventually completely isolates the component lead out wire from the copper track on the pcb, although I couldn't see anything with the naked eye. The pressure from my meter probes, and perhaps temperature variations when it had sometimes started working again for no reason, had been enough to restore continuity. I resoldered the 2 connections for the volume control, and did the balance control for good measure, and it's worked fine ever since.
 


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