peavey mace vt series head fault

[setat11]

Hi everyone, i bought this amp as working however now ive got it it doesnt! the problem seems to be with one of the 6, 6l6 valves, the last one one the right doesnt glow, ive tried swapping them and still the same so maybe its a wire fallen off inside where the valve sits, i though id ask the experts before taking it apart, any help appreciated

[Gtr_tech]

Check the wiring at the socket. If they're mounted to a pc board its prob'ly had a socket pin crack loose from the board. Resolder all of them while yer in there.

[setat11]

hi, thanks for your reply, ive just taken it apart, the valve socket is soldered to a pcb, ive tested the pins with a meter and they all appear fine, typically my luck, i knew it wouldnt be that simple !

[52 Bill]

hi, thanks for your reply, ive just taken it apart, the valve socket is soldered to a pcb, ive tested the pins with a meter and they all appear fine, typically my luck, i knew it wouldnt be that simple !

Did you try moving the one tube that doesn't glow to a different socket? It may just be a bad tube.

What are the symptoms of the amp? One dead tube out of 6 will not cause major problems, like no sound, etc.

[setat11]

hi, yes i tried that so the tubes ok, symptoms are all the tubes light up (except whichever one i put in the socket on the far right) but nothing, no output at all although , wierd !

[Gtr_tech]

If you have a meter then, check pins 2 and 7 of the faulty socket. Look for continuity to the like pins...IE pin 2 on all the output tube sockets are hooked together, same with 7. 2 and 7 are the heater pins, so start there and work outward. You may have a broken pin inside the socket....inspect it from the top side and make sure all the pins are intact. I had this happen with a reissue Vox AC50 type thing. One of the pins broke inside the socket (the pin for the screen grid) and effectively shut that tube off leaving the remaining output tube to do all the work....it wasn't happy about it.

[setat11]

update (still not working)

Hi again just to let you know ive cleaned all the valve sockets and the pots however still nothing, by the way these are brand new valves from russia as i bought the amp without valves although i was told it was working before he removed the valves for another project, usual ebay hes now "no longer a registered user"

[52 Bill]

While it could be a bad socket or circuit board trace, the major problem lies somewhere else. I wouldn't focus too much on the output tube light up problem until the "no sound" problem has been dealt with first.

Do you have a schematic for this amp? If not contact Peavey via their website and request one. They will email a pdf of one to you.

Have you checked the high tension system yet? Are voltages present at the output transformer, plates, screen grids, etc.?

If the amp has an FX loop or a pre-amp out/power amp in break jack set, have you tried to bridge these with a spare guitar cable?

Edit: Ok, the schematic is available at Schematic Heaven. The export model of this amp has fuses on all of the transformer secondaries. Have you checked all of the fuses? Plug a guitar into the power amp in jack, do you hear any sound?

[setat11]

tried

hi thanks fot the info, all the fuses are ok, also ive tried making the loop and plugging a guitar into the power amp in jack but still nothing, is it time to bin the thing do you think

[billybillybilly]

ive got an old peavey 70s festival duece , the power amp section is basically the same as the mace vt .
mine had 2 problems :
1 - the phase invertor transistors were bad , not sure why , but i replaced both of em , coupling caps , and the bias cap and trim pot as well .
2 - one set of the output tubes barely lite up . the heater wiring had come loose at the tube socket . it was a bad solder connection .

once those were dealt with , and a filter cap job , its fine ... and LOUD !
hope that helps .

but , being a bit of a scavenger and a pack rat , if you decide to give up on it , keep the chassis atleast ... or i would anyway .

[52 Bill]

hi thanks fot the info, all the fuses are ok, also ive tried making the loop and plugging a guitar into the power amp in jack but still nothing,...

Then the problem is in the power amp section.

...is it time to bin the thing do you think

I don't know. I don't know how much you want this amp and how much time and money you want to spend on it. Sell it on eBay as a project.

[Amp Kat]

How much do you want for it ?