What's up with my amp?

[el cheapo]

Hello! I'm the proud owner of a newly acquired 50 watt Peavey Bandit. This amp was made in 1982, and spent the last who knows how many years in a basement.



I cleaned the old girl up, sprayed out the pots and everything seemed fine. It actually sounds pretty good! I've been playing it for a couple of days now, and I've noticed something. Every so often when I'm playing around lightly I notice kind of a crackly sound, and then nothing. The power light stays on, but I get no sound. If I hit a chord the sound comes back. It almost seems that when the signal from the guitar is weaker it won't come through all the time, but when I play a chord or strum harder, the signal is strong enough to come through easily. What gives?

[Lunchie]

Im no amp expert but i would guess a bad jack in the amp. Thats where i would start.

[Robster]

Did you clean all the jacks? Even the ones on the back of the amp?

[el cheapo]

No, I just sprayed the pots. What's a good way to clean the jacks themselves?

[telex76]

Just spray cleaner/lubricant in the jacks and plug and unplug them 5 or 6 times to get them clean.

[andyfromdenver]

I you have some pipe cleaners and deoxit. Open it up. With insides of jacks accessible plug a 1/4" in to expose the shorting tab and scrub it out with the deoxit on the pipe cleaner, as well as scrubbing the tip. Hopefully that solves it, but it'll be good maintenance either way. While in there look for any cracked solder joints, that may be the culprit.

[hackworth1]

I suspect a cracked solder joint. Could be nearly anywhere and difficult to detect.

[andyfromdenver]

Sorry I just realized too that the maintenance I was referring to applies to switchcraft style shorting jacks. That may have the pcb mount jacks. Maybe touch up (reflow) all those areas where it solders to the board. That cooooould fix it :)

[el cheapo]

Well, I was able to tear the amp apart and get all the jacks cleaned out. They were the old style switchcaft jacks and pretty easy to deal with. I put everything back together and started playing. About a minute later the amp cut out on me again!

I turned it off and back on again, and it was playing again immediately. I don't know what to think now.

[hackworth1]

Intermittent cracked solder joint. If you disassemble the amp and search the board, you may find it. Could also be a bad connection on one of the snap-in type wire ribbon connectors.

The Trial and Error Method can be used to find the faulty connection. If you pull it apart carefully and label the connections, you can reassemble it. If you are very lucky, the problem coud fix itself from doing that.

[el cheapo]

Originally Posted by hackworth1

Intermittent cracked solder joint. If you pull it apart carefully and label the connections, you can reassemble it. If you are very lucky, the problem coud fix itself from doing that.

When you say "pull it apart carefully" do you mean unsolder the connections? What are the chances of me getting zapped?

[andyfromdenver]

Well, I think it's time to take it to a pro. The chances of zapping are high. There are lots of good vids and threads on draining caps, and that amp probably has bleeder resistors, but the gamble isn't worth it IMO. If they're not in there with you turning it off and on, there is likely a stored charge on the caps that could hurt/kill you.
Sincereiously,
Andy
Ps. I just made that term up earlier today :)

[hackworth1]

This dude's handle is el cheapo. Will he take this $50 amp to a tech?

Unplugged, chance of getting zapped is 30/70. Get it playing, jam on an open e chord.
While strumming, turn it off. Do you hear the sound fizz out after you turned off the amp?

[el cheapo]

There is no "fizzing". It's either playing or it's silent when I turn it off. It seems to make a staticy or crackling noise before it cuts out while I'm playing, but if I strum a chord it comes to life again.

[Robster]

did you clean the jacks in the back of the amp too? Make sure the wires on the speaker are on tight? If there are any ribbon connections in there make sure they are tight.
Look for any bad solder joints or ground connections or anything that looks like it overheated in there.

[el cheapo]

Having no experience working on amps, I decided to take it to a local amp tech. He said he would take a look at it for me. I called him after a few days and he said that he straightened up the bent input jack, and replaced a couple of capacitors. When I asked him if he found why it was cutting out, he said "Well, it's an old Peavey amp. Could be a cracked solder joint or something". The guy wants to charge me $80.00 for what probably took him 15 minutes to do, and the original problem that I asked him to look at remains unfixed.

Question: Would you guys be a little pizzed off about this?

[Keyser Soze]

How specific were you when you brought the amp in to the tech? Did you speak to him directly, or someone else behind the counter. Did whoever you spoke with write up a work ticket at the time you dropped it off?

What was written on the ticket?

Did you say anything that would have given him permission to address other concerns?

I'm guessing he replaced a couple of the electrolytic caps in the power supply. Which may have been a good idea, but if you didn't ask for it, then I'm not sure why he did it without your permission. The bent input jack needed to be addressed to rule it out as a source of the problem, so that was a given.

Start by asking him -specifically- why he didn't address the problem you described.

After that it is going to be a negotiation.

Worst case scenario you are out $50.00 and the tech is now the proud owner of a wonky amp.

[andyfromdenver]

Ouch, $80 is more than I would have expected. If it is fixed ok, but sounds like you weren't given a strong assurance. Before you leave with it, play it a while and turn it up and see if it's fixed. Also, maybe bang a corner on the carpet to see if it cuts out.

[pajur]

Listen to Hackworth,

When you play loud, something moves in your amp from the speaker's vibrations and the intermittent joint acts up.

The tech charged you $80. He should have looked for the main problem but on the other hand, he has spent significant time looking. Somebody has to pay for his time and expertise. This is a problem with any repair work but it will remain unresolved until the end of the world, I suppose.

[burninwordz]

Dude you got el jebbo from el tech;o now your a sorry el cheapo IMO just follow the instructions the guys give and you'll be able to fix it and you will gain experience. which is worth more than the $80 bucks.it's really not that hard to check