Peavey Triumph cuts out until it warms up.

[guitician]

The first pic is from the power supply board. It doesn't look like there's any breaks in the trace but I need to get a better magnifying glass and check again.

What are the traces that have the coating scratched off? Are they carrying a large difference in voltage potential? That could cause problems. May be a nail polish fix?

[stoneattic]

What are the traces that have the coating scratched off? Are they carrying a large difference in voltage potential? That could cause problems. May be a nail polish fix?

I'm at work and don't have the board in front of me, but looking at the schematic and trace layouts in the post earlier, it looks like they come from the "Hum Balance" pot which appears to be part of the heater circuit. Oddly the two outer ones appear to be the same trace. So one (either the two outer or middle) is ground and the other the 6.3 heater voltage. When it cuts out the tubes are all still glowing, but maybe I need to wait longer before flicking the standby to see if they dim. Any idea how long it would take for the heater glow dims?

[pinevalley]

Not posted on this in a while...I have since had the chance to get further into the amp. I was able to eliminate the cutting out by first cleaning the tubes and sockets with DEOXIT(did nothing for the problem but lubed them up nicely). Slightly moving around the V3(12AX7) WAS still causing the signal to cut out as well as was the V4(12AT7). Which was replaced with a spare 12AX7 since I cracked the AT warming it up to remove it (some dufus went a little crazy with the hot glue at the factory and glued it to the socket.) Resoldering both sockets ( just heated them with an iron to make sure the connections were good) seemed to clean things up nicely. A little hotter gain due to the higher gain tube in place of the AT. Actually sounded pretty nice on clean. Stevie Ray hot. Well after a bit of sawing I smelled the warm amp smell you usually smell once its warmed up. But soon after the lower end jumped off and never came back. Volume is still there in the mid to high range just no low end. Did I F#CK things up by using too hot a tube in the AT socket? If so what might I start to look at checking? Filter caps? It was all going so well too...

[nashvillebill]

The 12AX7 not only has hotter gain, but also has slightly different electrical characteristics than the 12AT7. One half of the 12AT7 drives the reverb and the other half is the final gain stage prior to the phase inverter (if my memory is correct). Changing to the 12AX7 probably isn't a great idea but I suspect it wouldn't do any damage (though I'm not an expert like many of the great folks around here are) for a short test.

I've had my Triumph for a couple of months and I've dug deeply into it. As amps go, it's a challenging amp to work on, with the multiple stacked PC boards. I'm hoping I can solve some of the reliability problems and make it a great amp, but it's taking a lot of work (and I almost have an idea of what I'm doing).

What I'm getting at: merely poking around and swapping tubes likely isn't going to solve your problem. Even taking out components and randomly soldering stuff won't do much either, in fact these circuit boards don't take kindly to lots of extra soldering. Plus, as I mentioned in a post way up further on this thread, the Molex connectors are a likely trouble spot; unplugging them, jiggling wires, etc, can break the flimsy little connections.

I guess I sound like a party pooper but to really fix an amp *usually* requires a modest amount of test equipment (primarily a good multimeter) and a knowledge of electronics. There could be a bad solder joint. There could be a failing coupling capacitor. There could be a bad wiring connection. Tracing out a schematic and logically troubleshooting is the proper way to find the problem....

[pinevalley]

You got it. Its all for the love of chasing TONE that we do what we do! The Triumph on the clean channel is one good sounding little amp for the money. Punchy and tight in the frequencies that count. Always careful with the Molex. If you handle them right not much bending is needed but I don't pull the boards unless its really called for. I did get in a couple hours of poking on the amp last night. First I was able to get the full tone to come back around for a visit then it was off again. At least nothing is cooked or blown What was obvious right off is that there is still some glue residue in the AT socket that needed cleaning. (read earlier post)It was melting and creeping in for the last 22 yrs and was keeping the pin clips from closing fully around the pins as well as hindering a good connection. The tube didn't feel like it was real tight in the socket so after much tedious effort, its is as good as it gets short of pulling it and dunking it in solvent to remove the glue. Have you done any mods to this amp yet? (Someone earlier posted a resistor group pic that looked like a mod) There are 2 sort of popular mods I read of. I have only done the "Thick Mode" bypass mod so far and installed a mini toggle to reconnect the jumper- so you can always have the option of stock again. The other mod I want to do is bypass the clipping circuit. Supposed to give full picking dynamics and let the notes sing free. First I need to finish cleaning up the dirty signal issues.

[necksnapper]

I have this same amp with exact same symptoms. Did you get yours resolved? I'd love to find out the outcome.