Peavey 45W PA-100 Tech Says Junk It !!

[Roly]

Maybe I should get myself an old Goldtone and start another project  8|

That, or build yourself a Lamington.   

[Andy54]

Two weeks later.

Guess what ? Yes you probably know what I'm going to say.  The same static has started again  :trouble

I'm assuming I should start with the same fault finding process again ?

All very strange as the amp was "whisper" quiet after the initial fix. I should imagine that as this is
an old amp this sort of thing comes with the territory. Nothing new to you guys that have dealt with these
things for decades.

[Roly]

Guess what ? Yes you probably know what I'm going to say.  The same static has started again  :trouble

I'm assuming I should start with the same fault finding process again ?

Well that's more than slightly annoying.

Basically yes, except hat the first place you look is where you did the repair.  The fact that it went away means that you "touched" it.  Now you have to have a closer look and see how it is that you touched it but didn't actually make the repair stick.  You are right on it, the transformer lead, the solder joint, or the copper tracks right there; something about it got touched enough to make a difference for a couple of weeks, but it was a very near miss.

And yes, these are what we call "bouncers" in that you chuck 'em out the door, supposedly repaired, and the bounce back in again onto the service bench.  Bouncers and intermittent faults are a tech's two favorite things  :trouble , and they often go together.

Honestly there is not a lot that we can help you with now because it comes down to close observation - bright light, good lens, and your trusty ohm meter - but at least you now know where to start looking.

Keep us posted on your progress.

[Andy54]

Thanks Roly, I'm sure it's just a matter of time.

Just to confirm, in your humble opinion,  this problem is most probably mechanical rather than faulty components ?

BTW thanks for the link to the Lamington amp, it could be a great winter project after this bugger.

[Roly]

{Nothin' 'umble' 'bout my 'pinions}

Is it mechanically sensitive?  Does thumping the case or poking the board produce any change at all?

I can only repeat what I said; you have been very close to it because it changed radically after you soldered up the connection to the transformer; and that made sense because it is a heavy component on a fairly flimsy board; so I would go for a good snoop around that area.  But the second thing is that if this is the same/related/unrelated mechanical fault there is practically nothing we can add by staring at the circuit - a broken track or dry solder joint are not on the circuit.  Very carefully and closely investigate what you repaired before, looking for what you might have missed, the cracked track, the transformer lead on the other side that didn't solder properly, whatever...