B52 ATX100 repair

[M Fowler]

This B52 ATX100 has had several owners and then my friend bought it and asked if I could check it out, had noise and wanted new tubes 6l6GC installed and bias.

Tube checked all the preamp tubes and output tubes which were fine.

Amp had a burnted 10k/3w dropping resistor for V2/V1. Removed the PS board after taking photos and notes. Replaced the burnt resistor, cleaned up the burnt PCB and reinstalled board.

Well I was careful but not careful enough, sure enough had two brown wires connected wrong and boom went a 10uf/63v bias cap. My mistake, but replaced that with 10uf/100v and reinstalled PCB again. Amp worked great so installed new tubes bias to 30mA per tube or total of 120mA.

Too nasally for my taste but guys like them so each to their own.

Now a good amp tech would never make such a bad mistake.

Took some photos if you like amp porn.

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[Stevem]

Even if I only remove just 2 wires from a board I note down where they came from!
One time I did not do this on a Marshall with like 12 plug in jumper leads going to two other boards that I let sit apart for a week and I found the Marshall wiring diagrams of little use to get verything plugged back in right!

What I eventually had to do is track down a guy with the same model Marshall I fixed a year before and ooen his up to figure it all out!

On your amp there what concerns me is why that resistor went south?
One reason could be the power supply filter going bad on the down stream end of that resistor.

[pompeiisneaks]

I always take pictures of the amp before taking out wires etc, so I can figure out what goes where

~Phil