NAD 7140 receiver no sound

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- borgunit2003
  
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posted
19 years ago

Thu, Mar 24, 2005 2:41 PM

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

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- Tim Schwartz
  
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posted
19 years ago

Fri, Mar 25, 2005 1:00 PM

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

snipped-for-privacy@yahoo.com wrote:

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- borgunit2003
  
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posted
19 years ago

Tue, Mar 29, 2005 12:13 PM

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.