Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Garrett335 on January 29, 2023, 07:11:00 pm
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Howdy folks,
I'm having an issue with a blues Jr. I'm working on for a friend. I just performed a recap added a switchcraft jack, the amp sounded great until I turned up the reverb. When I have the Vol and Master on zero and turn up the reverb pot it sounds like the amp is on 10 with a lot of buzzing.
Chop stick test is coming back with nothing, the reverb is strong and healthy but the buzzing is terrible.
I've just read and double checked that the reverb circuit is after the master volume, but wondering what could be causing this.
If a bad IC wouldn't the reverb not work? / Doesn't appear to be a connection issue since I can't make the amp to make any noises while tapping it.
Noise only goes away while removing the PI V3.
Thank you for any input on this!
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Reverb circuit/ tank ; ground missing
Did the reverb do this BEFORE you work in the amp ? It is a must to know
Amp work fine before; check you job
Ribbon cables are very fragile. Their critical position is badly bent and can cause problems even if I think it is very unlikely that this is the only cause.
Volume and Master volume are before reverb pot and reverb circuit in the amp.
It make no sense with Volume and M. Volume at 0 you can hear guitar like amp is a 10
Or you mean Reverb make a very very loud buzz. ? Ribbon cābles ? Reverb circuit/ tank ; ground missing!
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Thank you Latole,
I don't believe the reverb circuit was making this sound prior.
I did have to take the boards out for these repairs so possibly something came loose. There were some shoddy repairs done to this amp in the past, several pads are missing and jumpers added etc.
I'll double check all the connections reverb cables and ribbons.