Tube Amp Archive

Well, last night I put in the new transformer. I got 10 minutes of loud playing with no drop out, so i think (knock on wood) this ampeg is back in bidness!

thanks for the help!

Lesson learned: measuring AC voltage is a helpful diagnostic tool

I tightened the tube sockets when I first started working on this, but they weren't really loose at all, and are in really nice shape. I will spray some deoxit in there just to be sure though... Also, I measured the resistance of all sides of the OT at the beginning, and found both sides of the prim...

I tested this by playing guitar instead of a test tone, so I could hear through the speaker when the event happened. At pin 6, I averaged 50vac while playing hard chords. The dropout had no affect on this on either tube. I checked the vac on the ot secondary at the speaker out jack, with a speaker c...

It has a pair of 7591 outputs, 7199 phase inverter, 6cg7 reverb and 12ax7 trem and preamp tubes. I pulled the reverb and trem tubes to narrow down the possibilities. Heaters measured right on and sockets match the schematic. With an intermittent problem, I am looking for a faulty part, solder joint ...

Thanks for the tips xtian! However, I have a few problems... The big one is that the "clamp" last for only a few seconds, and I cannot make it do it reliably, so while running a test tone into it, I have no way of telling if it has occurred, and when it does occur, there is little to no te to diagno...

Do you have any pictures? Can you verify if the oscillator is working? Also, have you tried removing the bug from the amp? You should take a look at the schematic, and measure voltages with the associated tubes. It sounds like the oscillator is good, since you can hear ticking, but it doesn't hurt t...

I've been working on this amp off/on for a few weeks, working out the bugs, and have it narrowed down to one final, annoying issue. I was really hoping to do this overhaul solo without asking for advice, but I think I'm getting into the "replace parts just because" stage, which I am completely again...