Smitty wrote: ↑Sun Mar 09, 2025 1:03 am
Have you validated this condition or is this what the owner is reporting? Your last pic of the chassis does not show that the reverb mixer has been modified. I can't see the pot, but if it is connected according to the schematic it would be very difficult for it to act as a master volume--even if it failed.
Yes, sir... I have validated said condition. After much net perusing and reading, I believe the issue to be worn-out reverb tank cables. They were in bad shape... hoping that it's a faulty ground connection due to these badly worn cables. The shielding I could see was missing in pieces and broken in places. Got replacements on the way. We shall see if that is indeed the problem... thank you, again, Smitty.
Unsolder the brown wire from the Reverb pot wiper. Measure the resistance to ground of that wire. it should be about 700K. If the 470K resistor is shorted you'll get 220K. That would allow the condition you describe.
The amp should work fine with the reverb cables unplugged. Just no reverb. Unplug the cables an test for the master volume condition. If it persists you'll know it's not the cables.
Smitty wrote: ↑Sun Mar 09, 2025 2:19 am
Unsolder the brown wire from the Reverb pot wiper. Measure the resistance to ground of that wire. it should be about 700K. If the 470K resistor is shorted you'll get 220K. That would allow the condition you describe.
The amp should work fine with the reverb cables unplugged. Just no reverb. Unplug the cables an test for the master volume condition. If it persists you'll know it's not the cables.
With the Reverb cables unplugged, the Master Volume condition is nonexistent - unplugging the cables renders the Reverb control's function to null. The ol' process of elimination leaves me pointing the finger at the Reverb cables. Thank you for all of your expertise, Smitty. It is immensely appreciated, sir. You are, indeed, a gentleman and a scholar.
