NAD 3020A with Dead Channel

[organicdonut]

Hoping for some guidance on an issue with a NAD 3020A with a dead left channel. But, with headphones in, both channels work fine and balance switches fine from left to right. As a preamp to a NAD 3140, both channels work and balance again works fine from right to left. So it's in the amp or there's a problem with the speaker terminals.
Not an issue with the source inputs, as the problem happens regardless of which input is used. And all sources play fine when the 3020A is used as a preamp.

I've already checked the preamp out/amp in RCA connectors and reflowed them and tried with different jumpers. Cleaned the switches and all turn without static. No blown fuses, so the output transistors should be fine, right?
Checked the speaker terminals and reflowed the solder.

If the amp had a dead channel, would the headphones still work with both channels?

 

[Rob DeFries]

It could well be the headphone input. It switches the loudspeakers off when you enter the headphone plug. The contacts can get dirty. Move the plug in and out several times, spray it with some cleaner and move the plug several time in and out again.
Don't spray like a madman, the input could be open on the backside.
In the worst case you need a new headphone socket. Or get it out of the signal by bypassing it.

 

[organicdonut]

Thanks for the suggestion. Cleaned the headphone inputs with DeOxit, inserted and removed the plug a few times, but no change. Also removed the speaker terminal jacks to see if they were damaged, but they were fine. I have a few parts NADs and will try replacing the headphone jack. But since I rarely use the headphone jack, how would I bypass it?

 

[organicdonut]

Closing the loop on this thread. It was a faulty headphone jack! Thanks for the suggestion!