Vox AC15 clone output

[bzzztraffe]

Just did some troubleshooting & repair on a Vox AC15 clone. Repairs were a success & all was working well until I nudged the gain into some breakup. It initially sounded great, but started bottoming out so I turned the input gain (no master) back down into the clean range, but the amp continued to fart out a little. I cranked the input gain & in a few seconds the output began to gradually choke out & sputter. Now there's no output at low gain & only hard transients poke through at full gain. Tried swapping input tubes & no change. Power tubes & speaker are good (swapped them as well) & all components seem to be fine. I haven't encountered this problem before & am wondering if the output transformer went bad.....or something else?

[The Dude]

Got a schematic?

And,...... Welcome to the place!

[Chuck H]

It may be a cold solder joint. If you can, trace the signal from the input forward to see if there's a place where it drops out or acts funny. A cold contact may not be in the signal chain itself, It could be in a circuit that dictates the operating conditions like the power supply rail or a cathode circuit.

[The Dude]

If it has an effects loop, it could also be a switching jack.

[bzzztraffe]

Checked all solder connections
Cranked it & tapped every component with a chopstick
No effects loop
All electrolytics look good
Speaker is good
All tubes are new
Still the problem persists

[The Dude]

Do you have a scope? If not use a DVM set to AC volts, insert a test tone, and follow the signal through the amp. See where it gets lost.

[nosaj]

Checked all solder connections
Cranked it & tapped every component with a chopstick
No effects loop
All electrolytics look good
Speaker is good
All tubes are new
Still the problem persists

Out of curiousity what exactly do you mean by Electrolytics look good?

If you think it could be the OT what voltages do you have on the output tube plates?

nosaj