bassman hum
- Thread starter castiron
- Start date
L
Lewguitar
Guest
the guy who invented fire
Fuzzy. Guitars
Re: bassman hum
Yeah...flip the cord or flip the ground switch in the back...either way the amp likely needs a cap job and you need to dump that 2 prong cord and go 3 prong...
Yeah...flip the cord or flip the ground switch in the back...either way the amp likely needs a cap job and you need to dump that 2 prong cord and go 3 prong...
kevlar3000
Bullet Proof Toneologist
Re: bassman hum
I would address both, my 68 benefited greatly from it.
I would address both, my 68 benefited greatly from it.
Re: bassman hum
Others have already said it but, your filter caps are dead, so are the rest of the bypass caps and the bias cap. Your screen and grid resistors are probably getting tired. All of your 100k plate resistors are probably water logged and noisy, but you do not know it yet because of all the 120 hum. You may have a bad/broken ground connection also. Your pots are dirty, and so are your jacks and tube sockets. You may have some micro tubes, but again you cannot tell yet because your filter caps are gone.
Don't let me bum you out, just a typical laundry list of things to check. If you can pull the chassis and the silver cap cover (dog house), and post some pictures it would be easy to diagnose a lot of this stuff. If it really is an AA, you have a bit of a unique amp there. But again, don't let me scare you. For 250-350 dollars of maintenance, upkeep, repair, you will have a first class amp. Oh Yeah, after you get all the e-caps replaced, verify everything else is square, and set the bias, don't be surprised if you burn down the power tubes that have been in there for the last 10-40 years.
It all just depends on how your amp was maintained over the years. It may already have had a cap job and new tubes. You might just have a bad ground. Maybe just a $60.00 repair. That really is an awesome transition amp you have, and will be for years to come. Please post some pictures.
Congratulations
Well Done
Others have already said it but, your filter caps are dead, so are the rest of the bypass caps and the bias cap. Your screen and grid resistors are probably getting tired. All of your 100k plate resistors are probably water logged and noisy, but you do not know it yet because of all the 120 hum. You may have a bad/broken ground connection also. Your pots are dirty, and so are your jacks and tube sockets. You may have some micro tubes, but again you cannot tell yet because your filter caps are gone.
Don't let me bum you out, just a typical laundry list of things to check. If you can pull the chassis and the silver cap cover (dog house), and post some pictures it would be easy to diagnose a lot of this stuff. If it really is an AA, you have a bit of a unique amp there. But again, don't let me scare you. For 250-350 dollars of maintenance, upkeep, repair, you will have a first class amp. Oh Yeah, after you get all the e-caps replaced, verify everything else is square, and set the bias, don't be surprised if you burn down the power tubes that have been in there for the last 10-40 years.
It all just depends on how your amp was maintained over the years. It may already have had a cap job and new tubes. You might just have a bad ground. Maybe just a $60.00 repair. That really is an awesome transition amp you have, and will be for years to come. Please post some pictures.
Congratulations
Well Done