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NAD 312 Troubleshooting

lost_sock

Member
Oct 15, 2020
1
0
20
I picked up a NAD 312 today, cosmetically it looks great, it was going for next to nothing so I took it untested. It has a gremlin that's a little baffling. Hoping if someone has experienced this before they can offer some insight.

The left channel is louder pulling the center image quite noticeably to the left. I had to adjust the balance to 3 o'clock before it straightened out. When the volume is all the way down I can still hear a very soft signal coming through only the right. I switched out speakers, cables, source and changed inputs and it's definitely the amp.

Next I started looking at the pre/main connections. I swapped the pre/main jumpers around, no change. I then replaced the jumpers with RCA cables, no change. This is where things got weird. I used the RCA cables to cross channels PreL to MainR and PreR to MainL... and now it's perfectly balanced and center!

That doesn't make sense!!! I would have expected it to pull center off in the opposite direction.

With my inputs also LR swapped everything is perfect. I would however like to get it working as designed at some stage, so if anyone has any ideas, please shout.
 

shadders

Well-known member
Nov 19, 2009
152
88
18,670
Hi,
Have you had the lid off and tapped the connectors etc with a plastic pen ? (plastic, as it doesn't conduct).

I have a relay issue on my Cambridge Audio Azur 650A. I have to switch inputs rapidly to ensure the relays make contact - as it causes the sound to move to one channel., or the other.

Regards,
Shadders.
 
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Gray

Well-known member
Nov 27, 2015
1,010
633
6,070
What with tone defeat and tape monitor switches, every source has to negotiate a few signal switch contacts on that amp.
Start with an internal visual check, especially of the solder side of the PCB.
Then clean all switches and control internals with 'Servisol' spray - before switching / turning them several times ( to wipe contacts / tracks clean).
See how you go from there.

I'm not saying Servisol is good, but the Pope recognises its ability to perform miracles.
Trouble is, it might cost more than you paid for the amp.
 

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