Tremolux Amp repair FINISHED

[xtian]

If the screen voltage is not below the plate voltage it will make the output fizzy. Simple enough to try, solder a resistor (1K) in series before the two screen resistors.

Great idea. Did lower the screens a couple of volts, but did not solve the problem.

[xtian]

Check the 10K's in the B+?

I did this next. And I thought, WINNER! Because the second dropping resistor had been replaced with 100K instead of 10K.

But, after replacing them both with 10K, per spec, amp sounds the same, just a bit louder. V1/V2 voltages are certainly higher. Same, damn fizzy, fast onset distortion when turned up past 3, though.

[Firestorm]

Latest photos?

I hate to raise the conductive circuit board issue, but you might check. I've been experimenting with a chemical fix, no report yet.

[xtian]

I hate to raise the conductive circuit board issue, but you might check. I've been experimenting with a chemical fix, no report yet.

Probed the board, but couldn't find any conductivity.

Just replaced the screen and grid resistors on the power tubes. Still no change.

Hair long gone from pulling.

[Firestorm]

Photos.

[xtian]

Photos!

[xtian]

one more

[Firestorm]

The problem is on both channels, right? Equally?

[xtian]

Yes. Already swapped the 0.1uF pair in the PI, then put them back because Blue Caps.

I can put about 9v p-p sine at the PI input before distortion. As expected?

[Firestorm]

The fact that it's coming in both channels confuses me. The Vib. Channel has very long leads, so phantom oscillations usually happen there.

[Firestorm]

The caps off the PI are the wrong way round, aren't they? Outside foil should be on the plate side I think. Might not make a difference. Lead dress is still suspect. Some long leads here and there but I haven't analyzed them carefully. Especially that grid lead to V6. Long.

[xtian]

I reversed the PI caps, just to be correct. Thx.

I shortened the power tube grid leads, and improved the lead dress around the OT secondary wires.

No change.

Recording of fizz attached, and new photo.

[jjman]

You've tried more than one cab, yes. Sounds like it could be a speaker rub, or other things.

[xtian]

You've tried more than one cab, yes. Sounds like it could be a speaker rub, or other things.

Oh, hell yes. Tried several, confirmed with known good guitars, cables, heads and cabs. Thx.

[Firestorm]

Yes. Already swapped the 0.1uF pair in the PI, then put them back because Blue Caps.

I can put about 9v p-p sine at the PI input before distortion. As expected?

Does this mean you're bypassing the preamps and still getting the problem?