NAD 3400 goes into std by at certain level

Should be mentioned that i just recapped the whole amplifier.
Double checked for caps in wrong direction and so....

I suspect might IC 705 can be involved.
Since it's connected to r channel, and somehow low level function.
Since it's sometimes goes into low level, before std by....
Was the amplifier functional before the re-cap?
Is this an induced failure?

IC705 is the useless MUTE/LOW LEVEL function, which is probably triggered when the processor detects the current/induced fault. It operates on both channels.

I'm guessing that when you stated the problem occurs when the VOLUME control is @ 50%, you were playing music. 50% of unknown is irrelevant!
Voltages and operating conditions are important!
You need to clarify what you were testing and under what conditions you were testing...

How did you determine that the right channel was causing the problem?

Good Luck!
 
I removed the pre out / main in link.

R pre out to left input plays well.
L pre to L main input same.

L pre to R main shuts down.
R pre to R main shuts down.

Also used another pre amplifier directly to main input, and it goes in std by
Nice diagnostic work! Now you need to find the problem.
Your "VOLUME 50%" statement suggests that the problem may be occuring when the high voltage rails are switched/utilised.
I don't have the circuit diagram available at this time, but check your previous work around the high voltage section of the power amp.

Good Luck!

EDIT: I've seen your post here. Apparently, the amp switches to Class A mode via IC705.
You need to inform NAD about this hidden feature (they may be surprised)!
Be careful when following information posted on The Internet (including this...).
It's ALL true (even if it's complete garbage)!

Are you testing the amp whilst connected to a 'lamp limiter'? If so, that may obscure the issue.
 
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