Peavey Heritage VTX

[lewie2792]

Greetings:

My old girl, a Peavey Heritage VTX has served me well since 1993. I am very fond of it. Recently on the job I had a cup of coffee on top of the amp (certainly not too smart) and you know the rest. While it was not a LOT of liquid, it dripped down on one of the 4 6L6 tubes and emitted smoke. I replaced all 4 tubes and now get what I'm told is the preamp sound (low volume and distorted) like it was on standby. Tubes have a normal appearance. However, no main power whatsoever.

Red power light is on o.k. Green status light will come on and almost immediately fade off when the amp is taken off standby.

Any ideas and suggestions would be certainly appreciated. Of course, I can take it to the amp man and wait a month but I thought I'd give the forum a try.

Many thanks, John L. Griffith IN

[Enzo]

OK, no lecture on drinks sitting on top of amps, you have already paid for the mistake.

Pull the power tubes, make sure no fluids remain anywhere top or bottom side of the sockets.

Turn on power without tubes, dim the room lights. ANy sign of arcing top or bottom on the sockets?

Now measure voltages. DC volts. Standby switch in high power operate position. Check for B+, probably close to 500v, at pin 3 of EVERY power tube socket. Check for B+ at every pin 4 as well. Now check for about +15v on pin 5 of each. yes, +15. This amp is driven through its cathodes.

Missing B+? Check for blown fuse F1, 1 amp.

All OK?

Put tubes in and fire up. Inside there are a couple 5 watt 3 ohm resistors. Is there more or less 30mv across each one?

Remember, the voltages this amp runs on inside can KILL YOU.

You have preamp out and power amp in jacks, use them. Send the preamp out signal to some other amp. How does it sound there? Plug your guitar into the power amp in jack. Sound like anything through your speaker? probably sounds crappy.

[lewie2792]

Success!

Enzo:
Many, many thanks for your advice. I was unaware of the presence of internal fuses (on the board) in this amp. I had never pulled the head out and hesitated to attempt it. Well, I just did it and found that one of the three 1 amp 250 v. fuses was blown. Replaced it and she powered up on the bench. Remounted on to the cab and she is just fine! THanks again!!

Best regards, John in Indiana

[Gtr_tech]

Did you clean the spill area while you were in there?

[lewie2792]

Clean inside

Actually, there wasn't a lot of fluid involved to begin with. The amp was on a stand tilted slightly back. The tube(s) took the main hit as far as I can tell. There was no evidence that I could see on the circuit board of any fluid stain. My first step was to replace all the tubes even though I suspected only one of them had been damaged.

It is a great amp and it has lived HARD for 16years. I keep it covered when not on the job so it still looks good. I clean the exterior periodically. I had found another on Craigs list and was ready to buy it.

Best regards,
John Lewis.

[glp]

Enzo, sounds like you've been in one of these before? I have one currently that makes a rather nasty distortion.... no matter what you do? I don't have a footswitch but the Normal Gain is where volume is most affected....

One of the 100 ohm 5 watt resistors on the power tubes was open, when I first opened it up, but I don't see any other issues? The tubes tested OK on an emissions tester.

Any ideas? By the way, following your steps above I found mostly 520 volts at the tubes.... although I only got 85vdc in a few places too!. The 3 ohm 5 watters were LESS 30mv.

Appreciate any thoughts.......

[Enzo]

Every part is in there for a reason, replace the open resistor before proceeding. An open screen resistor will shut down that tube.

Not fair to claim voltage readings "at the tubes" and "a few places." We have 520v at pin 3 and pin 4 or each tube? WHERE is that 85v? On one of the pin 4s? On pin 5? On pin 8?


Get the schematic from Peavey customer service and look at the specified voltages on that. Compare to yours.