Baffling issue. Can anyone solve this one?

[Enzo]

Every solder joint is doped, I assume from the "factory". If so, does that mean none of the joints have been resoldered? I would think resoldering a turret or other connection would boil off the dope.

[J M Fahey]

Same here.
At one point we are going to suggest retouching all solder joints, so kiss goodby to nail enamel.

But not yet (at least on my personal opinion), I like to find the real problem first; otherwise , you never know ... you *think* you solved it and then it rises its ugly head again, often at the most inconvenient moment.

Nobody is going to diss that amp, it looks gorgeously made; of course sh*t happens and thatīs why you have a problem.

It could also be inside a component where the lead wire is bonded to the guts.

Thatīs a distinct possibility. Specially on electrolytics because since soldering is almost impossible, specially when 2 very different metals are joined, tinned iron or copper leads are *crimped* inside to aluminum.

I can see it on the scope on the plate, grid, and cathode (6, 7, 8). Only that one triode though. It's not on 1, 2, 3.

Ok, weīll wait for the drawn schematic section.

And as you see, nobody cares about the maker, just the circuit and execution

[loudthud]

What I dislike about amps built in this style are the connections made to the turrets on the underside of the board. It's hard to inspect the joint, sometimes solder doesn't flow down the turret and wet the underside wire to make a good connection. I hate the idea of re-heating every connection in the amp. I don't see any soldering flux on the soldered connections, it may have been cleaned off during construction. If there is no flux, re-heating the connection can cause a bad joint. The one connection that looks iffy is on the 4th turret from the right on the row closest to the camera.

[gbono]

Probably a NOS capacitor. Age is not a benefit when it comes to capacitors especially electrolytics.

[fiveightandten]

Thanks everyone. So, I threw in the towel and it's back with the builder again. I'll keep this updated with the outcome.

[olddawg]

Thanks everyone. So, I threw in the towel and it's back with the builder again. I'll keep this updated with the outcome.

BTW, Did you try playing the amp somewhere else? Someplace with a different AC mains? I've seen artifacts and variations in individual's line voltage cause some pretty weird problems. I've certainly had performance issues in clubs because of it.

[fiveightandten]

BTW, Did you try playing the amp somewhere else? Someplace with a different AC mains? I've seen artifacts and variations in individual's line voltage cause some pretty weird problems. I've certainly had performance issues in clubs because of it.

Yes. I think I mentioned it in post 1. It did the same thing at home in multiple outlets, and at our practice space in multiple outlets. I've checked them all with an outlet checker, and the wall voltage is proper at both places.