Help! Amp tech question (I think I messed up but good...)

[tomz.]

First I'd like to say, thank fucking god I found the new board! I was a many year jam room lurker on the old board (zaboz), and like everyone here, was sad it went belly up.

Now, I need a lil help, and you guys have always been able to point me in the right direction in the past soooooo.....

Recently I bought a 1975 Peavey "Classic".  Not the classic 50 mind you, this is a little different.  Made like a Music man, it has a ss pre and a tube power amp. 50 watt, 2 x 12.  It's a pretty cool old amp, but it had a couple of concerns when I brought it home.

1.  Needs new power tubes (6L6's)
2.  There was no fuse, it was bypassed! (a hack job none-the-less.)

So off to radio shack I go and grab a fuse holder (the kind where you push in the fuse and turn it to lock into position...)
Undo the bypass and solder in the fuse holder and when I put the plug to the socket, BAM, blow the breaker!  Turns out the power tubes were SHOT and that's why the jackass PO bypassed the fuse.  Whatever, get some Rubys for like $25.00 and I'm off to the races.  The amp sounds great, it's warm and has headroom for days, just what I was hoping for.....until i fucked it up.

I reach around back to shut it off, the toggle switch is right next to the new fuse holder and I guess I wasn't paying much attention and I whacked the fuse holder and bammo, blew the fuse again.  I must have not had a good connection and the holder is cheap-o junk and it moved it and must have grounded it out on the case!

So I put in a better fuse holder, much better quality, replace fuse, go to plug it in and NOTHING!  Tried a different fuse, different outlet, and now have no power at all.  I am going to take it in to a tech, but was wondering if you guys have any idea as to what I may have done?  I'm so bummed (and broke) that I haven't even really been able to play this amp.  Doh, vintage gear, maintenance!

Thanks so much for any ideas and advice! It's nice to be back!

tom
(zaboz)

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[Hemisaurus]

first off, if it's a cheapo fuse holder, you sure it's not just the holder is busted? or the new holder?

you have a meter, and can check continuity?

clip onto the prongs of your power lead, do you have a low impedance between them, but not a short? you should be able to read the impedance of the primary winding of the power transformer (the unit is unplugged and the power switch is on)

the fault sounds like it's somewhere in your power supply, so if you can't find anything wrong continuity checking, you'll have to turn it on and check the voltages. be safe.

http://www.diyguitarist.com/Misc/J_Darr.htm

Also dumb question, you have check it for other blown fuses? It's unusual to have only one fuse for the whole thing, there may be other fuses mounted on the circuit boards inside. I'm trying to figure out exactly what model you have, is it a Classic 212? There's schematics for it at http://www.freeinfosociety.com/site.php?postnum=2410 but it's not a solid state preamp, it's just got a bit of solid state switching, so I don't know if thats the right model for you?

There could also be things like MOV's or a thermal fuse involved, which blow in overheat or short circuit conditions. MOV's look like big disc capacitors, thermal fuse like a small resistor, but it would be mounted on say the transformer where it would feel the heat.

if none of this makes sense, then yeah take it to a tech.

[tomz.]

Thanks Hemi,
Going to go through it again and look for another fuse and in fact check the new fuse holder as well.  Also I do have a meter and will check for continuity.  Now, that's the stuff I feel ok with, the capacitors and whatnot, well, the tech will get to those!  As far as the model, it would seem Peavey has used "classic" for many of it's amps through the years because it's not the classic 212, even though it is a Classic     212.
It's good to see you here, you had disappeared from the sr jam room for a while and people missed your knowledge!  Thanks so much for the help!

[tomz.]

Alright, quick update.  Took it to the tech a couple days ago.  Well, the tech dude works in the basement, chugging down marb lights and sucking on cold coffee all day, the guitar store owner is just as interesting.  Weird place, but they generally do nice work fairly reasonable.  The owner was stoked to see me bring in this amp, he even knew what it was before I got through the door, (I had the chasis pulled from the cab), pretty good sign.  I tell him what a dumb-ass I was and he says no problem, be ready in two days.  Fast forward two days.  Go in and he tells me bad news, I have a bad output transformer.  Fuck.  I've already spent way to much on this pos amp.  I go to the cellar to talk to Rif Raf the tech and he tells me they put in a new fuse holder and it powered up but no output??  I ask him if grounding out the fuse could blow a transformer and he say's most likely not, in fact he say's they rarely, if ever go out.  But don't worry, because we'll get it fixed.  For another $160.00 bucks. fuck.  Then I just decide to pay my bill (he charged me $25.00) and come here and ask more advice.  Get the chasis back to my shop and for shits and giggles plug it into the cab and the mother fucker works!

Still not sure if they were trying to play me as a fuck-tard or what, but what-ever, I got my amp back and it works.  I'm happy. 

Now, probably look for some fresh speakers to tighten it up a bit...

Thanks again for all the help!

[tomz.]

the tech kinda looks like this guy...

edit say, he may have well "forgot" to plug it into speakers to test it out...

[neighbor664]

Now, probably look for some fresh speakers to tighten it up a bit...

Don't you mean lighten it up a bit?  Those Black Widows are f'n dense. An old bandmate had one of those. I think Jason (Dr. Zayus) even was using it for a short time.