Ampeg V4B-AV

[booj]

Powers up – volume drops after 15 min. then fluctuates. I've re-biased the outputs. They had been set to about 7 watts apiece. After I re-biased it I let it run for about two hours to make sure the tubes were stable. I also figured that would fix it. Gave it back to the music store I work for. They called and said it ain't workin' right yet. I'm thinking of taking a rubber mallet to it and just beating about the head and shoulders until it gives. Anybody got any other more humane ideas? I can't run it wide open into a speaker load without the police shutting me down. I'm open for obious or not so obvious suggestions. Thanks!

[rf7]

Did you orange stick it on the bench?

[booj]

Ahh yesss. The internal rubber mallet. Thanks for the response. I shall give it its due abuse. And a re-slolder job. I'm thinking though of how to reproduce the effect of a vibrating cabinet at full power. Looks like both methods may be appropriate.

[lowell]

I'd suspect a tube, try some new ones and rid of that possibility first. Too many times have I scratched my head over an issue that turned out to be a tube.