NAD T 751 receiver - right channel quiet -- then I hit it then it plays fine -- ???

[Jimmy154]

NAD T 751 receiver
Right channel plays quietly sometimes, then I hit the top of the receiver and it starts playing the same volume as the left channel.

I read that when a NAD receiver had this problem it is usually a relay.
So I took it apart to clean the relay(s), but did not find any.

What could the problem be?
Where are the relays?
Should I take a picture of the inside?

 

[Ian Finch]

There are indeed relays for the individual power amplifiers. Take a look at the service manual and scroll down to the various audio amplifier schematics. On the right side of each schematic, you'll find the relay coils and contacts separated but they are there alright - perhaps physically smaller than you imagined. NAD T751 - Manual - Surround Sound Receiver - HiFi Engine

"Percussive maintenance" is a big club to fix a small problem. It could also be temporarily fixing something else like a loose or corroded connector pin, broken solder joint or even a broken circuit board or copper track so don't limit your investigations to just relays.

 

[rayma]

NAD T 751 receiver
Right channel plays quietly sometimes, then I hit the top of the receiver
and it starts playing the same volume as the left channel.

Could be lots of things, output speaker protection relay, most any of the switches, etc.
There is a relay at the output of each amplifier channel.

 

[mosfet madness]

Could be a lot of things as stated. But if you are competent you could remove connections (esp power!) and take the case lid off and have a good close look with magnifying glass and bright light. Look for tiny cracks on solder joints and pcb traces.... Especially big components like electrolytic capacitors, relays, input and output connections etc.



You can gently 'wiggle' and push pull on the component and if the solder or leg on the other side of the board moves then that is a problem that is easily cured by reflowing the solder with a soldering iron.


Hope this might help....


MM

 

[adason]

Just keep hitting it
I got similar problem with Yamaha preamp...there is like two dozen relays in it.
What i do, while it is playing, i go with scope probe from input, and follow both channels, till one can not be traced,
You need schematics though.