I have an SD 84-40 when I bought it the volume would fluctuate (sometime wildly) and there was a pretty fine hum coming thru the speakers. I re-capped and replaced all tubes the same problems are still there. the volume problem seems to be in the pot but it happens after the amp has been on a while. does anyone have any suggestions. I tried putting a fan behind it hoping it could be a heat issue but it didn't help
humm 84-40
- Thread starter roml3
- Start date
Re: humm 84-40
Never had my hands in one of these old amps.
Seems like you have hit the usual suspects already......just make sure you know the tubes are good.
With an amp of this age, cleaning all jacks and tube sockets is a good idea...especially the loop jacks, and the solder joints.
Are you pretty sure the negative bias circuit is working well, or is this amp Cat Biased.?
Just tossing out some quick thoughts...not familiar with these guys at all.
good luck
Never had my hands in one of these old amps.
Seems like you have hit the usual suspects already......just make sure you know the tubes are good.
With an amp of this age, cleaning all jacks and tube sockets is a good idea...especially the loop jacks, and the solder joints.
Are you pretty sure the negative bias circuit is working well, or is this amp Cat Biased.?
Just tossing out some quick thoughts...not familiar with these guys at all.
good luck
80's_Metal
Underglazed Hair Metalologist
Re: humm 84-40
