Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Big chief on December 29, 2021, 12:23:41 pm

Title: Fender twin reverb
Post by: Big chief on December 29, 2021, 12:23:41 pm

Silver face twin with master volume  squeal reverb when pot is set above 7
Tried 3 different tubes retintion tube sockets cleaned all connections V3 is microphonic to the touch no matter what tube I use if I hold my hand on tip of guitar cable and touch V3
The squeal appears to go away any help would be helpful. Thanks

Title: Re: Fender twin reverb
Post by: Lectroid on December 31, 2021, 10:28:05 am

When you touch the cable, are you touching the cable itself or the plug?   A plug's metal cover is connected to ground and it's possible that your touch is creating a new ground path for the circuit that is currently missing.  I would look at the Reverb pot ground connection, and any other grounded components in that circuit path.  Chances are one of them's loose or got a cold solder joint.

Title: Re: Fender twin reverb
Post by: Latole on December 31, 2021, 01:56:46 pm

Never, never touch a tube and other part of the amp in same time.

Title: Re: Fender twin reverb
Post by: Big chief on December 31, 2021, 04:23:50 pm

Bad ground at reverb pot thanks for your help