[daggerlee]

Took the amp out of storage where it had been for a couple of years. 
 
Tubes seem to be okay, both glow and voltage is stable.
 
Right MOSFET channel measures 0 mV no matter what - turn the trimpot all the way clockwise, then 10-20 turns counterclockwise, nothing, although sometimes the mV will fluctuate between 200mV - 1V, but move the trimpot anymore and it goes ack to 0.
 
Left MOSFET channel is stable and can be adjusted by the trimpot. 
 
I switched the tubes to make sure it wasn't the tubes that was causing the problem.
 
Any ideas?

 

[tomb]

Quote:

Took the amp out of storage where it had been for a couple of years. 
 
Tubes seem to be okay, both glow and voltage is stable.
 
Right MOSFET channel measures 0 mV no matter what - turn the trimpot all the way clockwise, then 10-20 turns counterclockwise, nothing, although sometimes the mV will fluctuate between 200mV - 1V, but move the trimpot anymore and it goes ack to 0.
 
Left MOSFET channel is stable and can be adjusted by the trimpot. 
 
I switched the tubes to make sure it wasn't the tubes that was causing the problem.
 
Any ideas?

Could be the trimmer was hanging on by a thread and came loose from taking it out of storage.  Do the tubes bias OK?  Short of some pics and a thorough inspection, I'm just guessing.

 

[daggerlee]

Took it apart and reflowed the solder for the trimpot... seems okay now! Wow, thanks tomb

 

[tomb]

Quote:

Took it apart and reflowed the solder for the trimpot... seems okay now! Wow, thanks tomb

That's great news!  Glad you got it fixed!

 

[daggerlee]

Now I have a new problem... there's a static hum/hiss in the left channel that's there and doesn't change with the pot. Amp sounds fine, music sounds fine... any idea? 
 
EDIT: think one of the tubes wasn't seated properly