On Tuesday, March 20, 2018 at 3:55:37 PM UTC-4, wrote:
Dave:

You are right on the relay operation - I should have caught that - and it makes sense that a power-drop would also drop output.

I will signal-trace, but given the symptoms, and with proper understanding of the relay operation, I am even more suspicious of the relay. Most of the caps are new (less than 10 years) and the switches, contacts and input jacks are clean. But, testing leads to better understanding - all good.

Thanks for your suggestions!

Peter Wieck
Melrose Park, PA


Many years ago I saw just one DPST protection relay go bad, but it would cause a noisy output or intermittent crackles as the volume was raised as one set of contacts were pitted.

But otherwise I'd say if one side is good, it's most likely not the relay as Dave pointed out. The best you can hope for is that it quits entirely. Nothing is easier than tracing a mute audio channel when there's a working one right along side of it, and nothing is worse than chasing an intermittent audio channel when it's working..