peavey classic 30 problem

[Enzo]

Dude, we can do the same test the other way. Clip an AC voltmeter across it, and operate the amp. When it cuts out, does 120vAC appear across the thermal fuse? That would indicate an open, even if said open closes itself when it cools. Anything is possible, but I have never seen a come and go thermal fuse.

g1, that is certainly possible, broken solder joint arcing.

[The Dude]

Yep, that works. You could also wait until it takes a dump, unplug it, and quickly measure the primary continuity. Lots of ways to skin this cat.

[52 Bill]

I don't think that I've ever seen one of those thermal cutouts act like a temperature cutoff, making and breaking contact. Usually they are closed or they go open and stay that way.

But anything is possible. I once had power supply diode in a Fender Bassman cycle open and closed like that and I didn't think that that was possible.

[The Dude]

Agreed on all counts, Bill. The protection device in any transformers I've seen is a thermal "one shot" fuse. Once it goes, it's not supposed to come back. It's easy enough to find out what's happening, though, with minimal testing.

[Breausonic]

Hey guys, just ran the amp for over an hour, no shutdown this time . Back panel gets pretty warm right above the 84s but not excessive.power trans you can put your hand on after an hour .Amp is quiet and i have to say I'm surprised how good these things sound.Ill get another thermal switch and put it in and see what happens from there.Thanks g-1 enzo the dude oc disorder bill52 for all the help guys!

[The Dude]

You mean it ran for an hour with the thermal cutoff bypassed or something else happened?

[Breausonic]

Hey dude, it ran for an hour with the thermal cutout bypassed sounded great no hum but i gotta work in the morning so i turned it off. no problems so far,ill try to get a thermal fuse from mouser to put back in there.Thanks and ill get back with you guys after i get the new thermal switch. Thanks Barney

[The Dude]

An odd one. Like Bill said, they usually work or they don't, but an Enzo quote comes to mind. "Never think of a reason to not check something".

[Enzo]

You bypassed it, OK, is it still in there? And if so did you resolder its ends to the internal wire terminals? If it has a bad solder connection, and we replace it, we will be resoldering it in that process. So we should verify it is the part itself or the solder on the ends of the part.

[tbonuss]

So its acting like a thermal switch not a thermal fuse (?). Sounds like the collective knowledge here is that y'all would highly expect it to be a fuse(?). Having very very little experience with guitar amp transformers I would then have to ask: Is it SO unlikely as to imply that its the "wrong" part, perhaps previously replaced when the skid marks were made?

I looked at the BOM but I didn't see it, maybe someone with better eyesight would find it.

[g1]

It won't be shown in the BOM, it is integral to the transformer and is not considered a serviceable part.