Peavey Windsor - Hum and White Noise Hissing

[Helmholtz]

C2 seems unnecessary.
But normal grid leak current might cause a voltage drop of maybe -50mV across the 1M grid leak resistor.
In a high gain amp this could cause audible gain pot noise.

[35L6]

Learn something every day . Thank you .

[TomCarlos]

Thanks gents.....

While I was doing my extensive analysis before this happened, there was zero volts on C2, before and after. I checked everything!!

My friend is coming over in a bit to test the amp with his pedal board. I'll try to ensure that he simulates his exact setup the other night, including the length of the instrument cables going to and from his board.

[TomCarlos]

Coming back to close this thread.... The amp has been working since my last post. So the cause of the Red Plating is still up in the air, wondering if a bad PI tube caused it. Anyway, all is good now.

One thing I did hear today... just before the Red Plating, amp owner made connections to the Send and Return jacks, while the amp was turned on, Standby off. I don't know if that could have caused the problem. But I did advise my friend to make these type of connections with the amp powered down.

Thanks again.