Peavey Classic 30 problems

[MarkusBass]

I've got Peavey Classic 30 with several problems, starting with old power tubes. While looking at the amp, I noticed few other problems. One of the capacitors looks very suspected. Do you think that this is failing capacitor, or this is just a glue?


Also, the board is discolored near 5W resistors in the power supply. Should I worry about it?


Mark

[xtian]

I wish there was better lighting on that cap photo, but yes, looks like it's compromised, and that gunk on the board is probably its guts.

The browning on the board is a potential concern--you need to look at the traces underneath to see if it's a critical issue.

[MarkusBass]

Let me try with a better photo:


You can see that other capacitors are also glued but this one has slightly different color. I think it's failed capacitor.

Mark

[nickb]

Don't hesitate - "if in doubt - swap it out" .

The cost of risking a failure in terms of immediate rework costs and reputation are not worth it.

While you are at it check the integrity of the the EL84 bases. The heat rises off the EL84s, the solder joints soften a little and the whole thing loosens downwards slightly. When you then press in a new EL84 the tube socket gets pushed back to the board and lifts the traces off the PCB. Not good.

[The Dude]

Agree with nickb. I'll add: Generally, when I do any work at all on a Classic 30, I try to be very thorough the first time. It's easy to break those connections from board to board (bent wires). If you are going to bend it apart and have to deal with getting it out and messing with it, you might as well give the whole thing a good "once over", take care of anything "iffy", and not risk having to do it again. Repeated disassembly and reassembly of those things only creates more problems.

[Enzo]

For the low price of a cap, be safe. However, I really doubt that is cap guts. That is glue. If it is discolored, it is from tube heat. Cap guts doesn;t look like that, and would not climb out of the cap then up and on top of it to harden. In the last picture you can see another cap further up the board, and the glue on it looks similar in color to me.

On to the resistors and jumper wires in the brown area. You really DO want to go over the solder under all that. The resistors are likely OK, but those connections, plus the ones at the other end of the resistors, may be in the process of desoldering themselves.

[xtian]

Agreed, that's probably clue. But I can see blistering on the positive end of that cap. Replace it.

[g1]

But I can see blistering on the positive end of that cap. Replace it.

There shouldn't be a weld at the positive (rubber) end, should there? Is that a solder blob?
(in circled area of 1st pic)

[Justin Thomas]

That ain't no solder blob... that looka like cap guts. Zoom in close.

Justin

[g1]

Hmm. If I look at the pic in post #3 it looks very silvery, like solder?

[Justin Thomas]

Checked both. Looks really granular and dull. Admittedly, it's not the same color insides as an old Mallory, but it looks to me like overheated cap goo. I dismantle about every one I find that's leaking goo, just for funsies. I've never seen a dropped solder blob look that rough, and the coincidence of it landing JUST right there... I bet if he pokes it with a stiff object, it crumbles or gives way.

Also, looking in the second pic in post 1, I can see little bits of the same stuff stuck on the surface of the brown glue. I think the cap did spew some guts, just not the dramatic explosion way like when you over-voltage them...

Either way, it ain't right. And remember - don't think up reasons NOT to check something.

Justin

[MarkusBass]

Thank you all for the feedback. I removed the chassis from the amp and checked everything as advised.
I looked at another cap in the power supply and it looks exactly the same. For me it is cap guts. I think that the temperature in the amp is quite high and the caps are for 85 degrees Celsius only.
Take a look at the other cap. I will replace both caps, although it is not that easy to buy them.


Another issue I found is that most of the tube sockets pins are cracked . For example the first tube - 5 pins cracked, the second tube - 6 pins, the third tube - 7 pins. This is really very sad because the pins are cracked mostly because the amp is incorrectly manufactured. There was not enough solder used. Please take a look at tube #1 and #2.

I already desoldered/resoldered tube sockets and now the board looks like this:


Mark

[nickb]

It's just too common with these amps. Here's one I did with the same pad lifting -



I cleaned the resist off all the track and soldered 16awg wire on the the tracks. I also pushed the socket in hard to the PCB and bent the pins over to help hold in place before re-soldering:



Also, like The Dude said, watch out for for broken wires:



With a little care you can test & probe on the bench:



Mark - if it's any help I do have 22uF 500V 105C & 22uF 450V 105C in stock. I'm out of 47uF 500V 105C - more in a few weeks. I do have 100uF 600V 105C but at 25mm dia x 51mm long they might be too big.

[MarkusBass]

Nick,

Thank you very much for your kind offer. I managed to order exactly the same capacitor as it was previously (unfortunately for 85 degrees).
The amp that I have looks slightly better that the one you had. But still, it makes me sad that the amp is manufactured in such a bad way. I'm looking at the text "Designed a built in the U.S.A." and my first thought is that there is nothing to be proud of . I'm not from the US but still it made me very sad. And I wonder how this is possible that the amp is built with such a low quality and with so many design mistakes (like e.g. missing ventilation for EL84 tubes).

Mark

[pontiacpete]

It also makes me sad that they keep making these 'C' shape board configuration