I find that the thermal fuses are indeed packed between windings, but they are also accessible if you dig through the paper.  Those silver diode looking things are thermal fuses, not common fuses.  You can wire past them and take your chances with safety.  You can buy new thermal fuses from a variety of suppliers like Mouser or MCM.  Look for Thermal Cutoff.

They are tucked in the edge of the windings rather than square in the middle.

And when ground traces do burn open, it isn;t always right near the rest of the problem.  They will burn open at the thinnest point, so there might be some large ground traces around the jack, but some little narrow point where it connects with other ground areas becomes the weak point and PFFFTTT.

Heat problems don;t usually operate on short time scales.  if it heats up enough to turn something off, then it has to cool enough to clear the problem.  SO if it is cutting in and out with any rapidity, then it is more a connection than a thermal issue.

Transformers like this won;t be in Mouser so much, but i bet you can find a pretty similar existing amp in one of the large lines like Peavey or Fender or Crate, and use the power transformer from that.

OK, it is a Bandit.

Looks to me like it has both sets of jacks - pre/power and the FX loop.  DO the tests.

PV transtube WHAT 112?


You got an FX loop?  Plug a cord from send to return.  ANy help?   Got a preamp out next to a power amp in jack?   Plug a cord from pre out to power in.  ANy help?   Got an "insert" jack on the front?   Plug something in and out of that a couple times.  Does that bring the sound back?  or if the amp was OK at first, does thart make it act up? (Note: it will cut out the signal while a plug is in the insert jack.  SO just poke in and out.)

Oops, didn't read the schematic first.

OK, it is a single supply amp, that means there ought to be about 18v on the + end of that cap.  If there is more like 30 or close to zero, then the output stage has serious issues.

With the outputs separartly driven it is possible to have a blown one and still get a little signal I suppose.  But if you can hear guitar, I start to think the problem is more likely powr supply, specifially that 2000uf ccap.

It will put 100 watts into any of those loads as long as the impedance selector is set for them.

What has probably happened is that the ground trace from the input jack has evaporated - blown open like a fuse - from trying to handle the mains current to ground.

Even if hte rest of it works, that missing ground will cause large hum when trying to play through the amp.

Looks like some small components burnt up, could be small value resistors to ground could be low voltage caps, etc.   Line 6 doesn;t hand out schematics.   Finding one will be just luck.

The first question is this, is there ONLY the very loud hum, or is the guitar sound still heard along with it?

And futher, looking at he speaker cone, when the amp is turned on, does the cone move one direction and then stay there?  Is ther DC voltage across the speaker?

If the guitar sound is heard along with the hum, then your filtration is not working.  A bad cap could be responsible, but a good cap can;t work either if the traces to and from it are not intact.

If the amp output is blown, you get DC voltage across the speaker - disconnect the speaker and measure for voltage on the speaker wires.  You would not hear the guitar along with the hum.

To me the key clue is that the static noise is continuos.  A dirty pot would make noise while turning, but usually would not generate a steady noise.  And the amp's input jack from the reverb pan could be noisy, sure.  Usually that would be hum.

The internal thermal fuses are not self resetting breakers.  They are a component that looks sorta like a diode.  or maybe a little cap.  Typically they are wedged between the windings - you have to tear the transformer apart to get at it.

Hmmm, when i read the post, I wasn;t thinking noisy pot.  I don;t think he means turning the pot makes noise, I THINK he means when the treble is up, the hiss of the system is increased.   Whatever hiss is already in there would naturally be made more prominent by turning up the treble.

I generally associate hiss with a gain element - in your case I assume an op amp or maybe transistors?  What active device is just before the tone control?

Sounds like a chip in the reverb recovery stage went noisy on you.

I used to buy that exact board 10 at a time.  I used the little breadboards to make up circuits, and it seemed easier to just transfer it straight over to one of those boards than make up a board from scratch.   ANd many times I needed a small circuit, I could just build it up at one end and saw off the remainder of the board for some other project.