Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ululufut on July 25, 2017, 07:33:13 pm
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I tried biasing my reissue tweed Bassman recently and messed something up, causing a pop/spark. Since then - although I don't know if there's a direct connection - the Normal and Bright channel seem to interact as if I have them bridged together.
What might be some possible explanations for this? I'd like to see if I can fix it myself instead of taking it in. I can't think of a relation between the two described events, and it was several days between my biasing mishap and the channel issue, however I can't think of anything else that might have triggered the problem.
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Normal and Bright channel seem to interact
In what way, you turn knobs on the unused ch and it changes the used one?
where did your bias land?
that's the PCB version?
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Looking at the schematic (So long as this is the same) it doesn't look to me like there's anything that's switching in this amp so you can't have something there, but the two volume pots are on the same part of the board for the controls, so if they're being interactive, something there may have gone bad.
Scroll way down to the bottom of this to see the schematic: https://robrobinette.com/5F6A_Modifications.htm
Also how were you adjusting the bias? That schematic and pictures I see on the web of the reissue don't seem to have a variable pot to adjust it. Were you just swapping one of the bias resistors?
~Phil