Scratchy volume pot in Twin Reverb

[lowell]

Hey guys, I hope everyone is doing well. So I have the 100 watt silver face twin reverb on my bench. It has a master volume but it is not the ultra linear 135 watt amp. I have replaced the volume pot in the vibrato channel, and I did that as a Plan B, after disconnecting the coupling caps had no effect on the noise. So I believe I eliminated the possibility of DC on the pot.

I even went so far as to insert a .1 microfarad cap between the treble pot center lug and the top of the volume pot. The scratching noise remained. I am baffled to say the least. Does anyone think it’s possible that a bad shielded cable from the volume pot center lug to the grid of that next recovery stage could cause this issue?

I’m baffled!!

Schematic attached

[The Dude]

Have you tried a different tube in the V2 position?

[Chuck H]

This^^^^^^^^^^^^^^^^^^^^^^^^^^^^

And, the only way to know if there's DC voltage on a pot is to test for it. There's no mention that you did.?.

Since you've isolated with the capacitor and replaced the pot... If the tube turns out to not be responsible there's the slim possibility of a conductive board. I hope not.