NAD 7140 receiver no sound

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Hi,
I am trying to figure the source of my problem. My NAD receiver does
not output any sound. I have tried the various buttons (TAPE Monitor,
selector, etc...) but nothing. I can hear a faint scratching when I
adjust the volume control (I assume dirty potentiometer) and I plugged
in a RCA plug to the AMP section and get a hum when I touch the other
end of the RCA plug so I am assuming the amp section is okay. Now what
might be my potential next steps to track the problem. It looks like it
would be the preamp section. Any help would be greatly appreciated.
Thanks.

JR

 

[Tim Schwartz]

JR,

There are so many possibilities. Since BOTH channels are acting the
same, I'd start by checking all of the power supply voltages. If you
don't know what I mean by this, then its time to visit a repair shop.

Regards,
Tim Schwartz
Bristol Electronics

 

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A follow up. I got the Service Manual and readjusted the preamp section
and speaker output per the instructions. After I did this I was able to
hear a broken up and scratchy output to
the speakers. I came to find the 4 pos selector switch also that needed
cleaned. Switching from Tuner/CD/Phono/AUX gave the sound back but
wiggling it caused slight drop outs. I sprayed it with contact cleaner
and it got better. I looked for a replacement one but it does not seem
an ALPS 4 position 12 lead switch is available anymore. I desoldered
it, pried the tabs back, and then cleaned the inner contacts with a
pink eraser and then coated the inside with lubricating contact
cleaner. I reassembled and resoldered it and now I am back in business.
Sounds great again. Thanks.