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1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Mon May 04, 2020 10:45 pm
by roylfuchs
I need help! My 1979 Superlead is having an issue with the volume. I'll be playing for about 5-10min, than suddenly the volume starts to inexplicably get loud. I give it a quick SMACK on the top and the volume goes back to normal. If anymore has had a similar issue and can help me
!
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Tue May 05, 2020 1:09 am
by glpg80
Assuming tubes are fine, I’d clean tube sockets, input and output jacks, and potentiometers. Start there. Next thought would be a cold solder joint.
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Tue May 05, 2020 6:01 pm
by danman
I would bet it's a bad solder joint on the volume pot's ground. One channel or both doing this?
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Thu May 07, 2020 12:21 am
by roylfuchs
This amp has actually been modified to a JCM800 spec. Plus, it has a PPIMV on the back.
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Thu May 07, 2020 1:34 am
by glpg80
Sounds like a cold solder joint. I’d take it to a tech at this point and let them chop stick it while on.
The other recommendations either of us have recommended still stand.
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Thu May 07, 2020 5:46 pm
by axeman
Is it in the brightness channel?
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Mon May 11, 2020 1:36 pm
by roylfuchs
SPOT ON!!! Cold solder joint on the back of the volume pot was actually broken off and just hanging there. Installed new 1meg and she's working beautifully. Cleaned all pots, sockets and jacks with Tronic Kleen. Thanks you guys for the rapid and super accurate response...saved me time and money! I was right on the brink of selling the amp. YOU GUYS ROCK!!!!
Re: 1979 Marshall Superlead Volume SPIKING!!!!!
Posted: Mon May 11, 2020 6:47 pm
by danman
Congratulations on the repair!!