Peavey Triumph 60

[Doc Stitches]

No tubes lighting up.... ( power or preamp )

Pulled and checked all 5 fuses ( good )

Power light and standby light work

Please see 2 pics : what might cause this female contact to burn/discolor ?

The male end ( pin ) solder joint was damaged so I resoldered it.

Thought I would ask before I put it back together.

[soundguruman]

An arching burning trace on the output board, or a bad tube.
Remove the output board. A lot of times it's riveted, you have to drill out the rivets.
In any case, you can't reuse that cable connector. Carbon on the plastic will continue to burn.
The carbon IS a resistor.

[nashvillebill]

Do you have the schematic and board layout? If not, see this thread here http://music-electronics-forum.com/t32214/ where I posted.

I suspect that is on the heater supply, which carries several amps of current. Probably a poor connection inside that Molex connector and it overheated. The heater supply is fused (F5) so if the fuse didn't blow you are likely OK. However, check against the schematic and layout to be sure what that pin went to.

Those &@!*% Molex connectors!

[nashvillebill]

Soundguruman, that connector goes into the power supply board on top, it's not arcing on the power amp board (that's the board underneath). The power amp board and tubes would be fine.

Peavey ran the heater supply weird on that amp. I'm pretty sure that's the heater supply on that pin.

[Doc Stitches]

Thanks soundguruman.....good call.....board is out and I will run new wire to avoid carbon.

I forgot that carbon is a resistor.

nashvillebill............. I do have the schematic.

[Enzo]

This is a common problem on any make or model of amp that ran the tube heater current through one of those molex inline connectors. If they got resistive at all they got hot, and the hotter they got the more resistive they became until they burnt the connectors.

It isn;t the connector's fault, it is the designer who said, I have a 5 amp contact, I think I'll run 5 amps through it. I imagine he drives his car around town up at the red line.

The cure is to hard wire the 6v feed across the connector.

[Doc Stitches]

thats what I will do tomorrow ( the hard wire connect )............have done this on some other amps as well

thanks all

[soundguruman]

Get all the carbon scraped off that board. It will cause headaches later on.
Yes, hard wire that pup.
Molex connectors were never really intended for the application, I mean the voltage and temperature is a bit extreme.
Should have been ceramic connectors.
All us PV techs have seen this happen, over and over again. My first PV service center was in 1975. That my friends, was before the dawn of man.

Heater track loves to arc to the high voltage. Once that carbon forms, it will just keep burning away. Even melts ceramic...into glass. That is pretty friggin hot.

[Enzo]

What voltage? These pins are carrying 6 volts, and the failure is from excess current for the pin rating, not arcs from high voltage. The molex connector handles the B+ and other high voltage perfectly well. Only pins to burn up are the 6v heater feeds.

[Doc Stitches]

Finished the hardwire and amp is working only on Ultra, High Eq. and Master Reverb.
No footswitch with this amp, and have changed out AT7.

[soundguruman]

What voltage? These pins are carrying 6 volts, and the failure is from excess current for the pin rating, not arcs from high voltage. The molex connector handles the B+ and other high voltage perfectly well. Only pins to burn up are the 6v heater feeds.

I have seen these output boards burn many times.
The tracks can burn right off the board.
The heaters do arc to the plate and screen tracks. Depends on humidity, a lot of times.
My point was, that once carbon forms, it can keep burning. On the connector or on the board.

The boards are held in by rivets, and this removal is frequenly dismissed because of difficulty.
But it is always better to drill the rivets out, remove the board and inspect it for damage, like burned tracks.
Then you can rivet it back in.
Better to inspect and be safe, rather than wait for it to fail again. I don't try to "skip" any step, to be sure the amp keeps working. I do it all, I don't assume that the problem is localized.

You do what you want. 99% + of my repairs don't reoccur again. That's cause I'm thorough, all the way through.
Like I said, I had my first service center in 1975. I have learned a bit about PVs, I would say.

[Doc Stitches]

OK... amp is working But only on Ultra, Master Reverb knob and High Eq are the only working knobs........No foot switch and I have changed out AT7

Removed and checked all 4 boards and repaired 2 bad solder joints.

[nashvillebill]

The output board on this amp is not held on by rivets, and the burned spot is on the pin on the power supply board that handles heater current, NOT the high voltage. So I don't know where all these burnt carbon tracks would have been?

I suspect another connection (to the preamp board) is causing the present difficulty, those little wires don't like the crimped on connection style.

[Doc Stitches]

The output board on this amp is not held on by rivets, and the burned spot is on the pin on the power supply board that handles heater current, NOT the high voltage. So I don't know where all these burnt carbon tracks would have been?

I suspect another connection (to the preamp board) is causing the present difficulty, those little wires don't like the crimped on connection style.

Thanks, I will recheck preamp connections

[nashvillebill]

Wait...stop the presses!!

You said NO FOOTSWITCH?

That's the problem. Without a FS, the Ultra channel is default. And the tone controls are inoperative when Ultra or Crunch is engaged.