Peavey Special 120

j0Nasty5150

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Dec 14, 2021
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Hello fellow musicians! I've been acquiring old PVs with good luck except for this Special 120 (and unfortunately a silver stripe Bandit). When played softly it seems to be fine when played heavy it pops, quietens and thins the sound. I banged the top of the amp, and it returns to normal. Play heavy again and it pops etc.

I assume it's a loose solder joint (or speaker?). I've already cleaned the pots and inputs. Can anyone share their thoughts on what this may be? I am not an amp tech and apologize for any "dumb" questions. Thanks!
 

codamedia

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I've been acquiring old PVs with good luck except for this Special 120

If banging on the top fixes it temporarily it is likely cold solder joints.

A thorough visual check & chop stick test (tap components with a wooden chop stick) should zero you in on the area... touch up anything that is suspect.

It is a 40 year old amp so you may want to replace the filter caps while you are in there. I just did my Special 130 not long ago, it's not a hard job if you know what you are doing. If you need to take it to a tech... the caps cost about $15 - $20 (total) and it should be about a 1 hour job. Those old amps are well built and easy to work on.

and unfortunately a silver stripe Bandit

Quite often the shorting jacks on these amps lead to problems... but it's an easy fix if that's the problem. If it is cutting out, or not making sound - try placing a small patch cord (eg: effect pedal cables) between the "send/return" on the front panel & between the "pre amp out / pwr amp in" on the back panel.
 

j0Nasty5150

TDPRI Member
Joined
Dec 14, 2021
Posts
35
Age
63
Location
Cleveland
If banging on the top fixes it temporarily it is likely cold solder joints.

A thorough visual check & chop stick test (tap components with a wooden chop stick) should zero you in on the area... touch up anything that is suspect.

It is a 40 year old amp so you may want to replace the filter caps while you are in there. I just did my Special 130 not long ago, it's not a hard job if you know what you are doing. If you need to take it to a tech... the caps cost about $15 - $20 (total) and it should be about a 1 hour job. Those old amps are well built and easy to work on.



Quite often the shorting jacks on these amps lead to problems... but it's an easy fix if that's the problem. If it is cutting out, or not making sound - try placing a small patch cord (eg: effect pedal cables) between the "send/return" on the front panel & between the "pre amp out / pwr amp in" on the back panel.
Thanks for the reply! I would like to learn how to work on theses amps, but at 63 I'm not sure if I should bother. I'll open it back up and see if I can spot anything, as I said I cleaned the pot already. Thanks!
 

mexicanyella

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Jan 26, 2012
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4,576
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Troy, MO
I second Codamedia’s suggestion: before opening it up, try the patch cord between the send and return, and also the pre out/power amp in (if it has those). If that fixes it, further cleaning or replacing of the switching jacks is all that’s required.

I have encountered this on my Special 150 and also my TKO115S bass amp.

If that does not fix it, take a look inside and see if it has the white plastic “molex” connectors anywhere. They are blocky squarish multi-wire connectors that push into male pins on the PCB(s), with spring-loaded female contacts in them, and they can oxidize and form intermittent connections. Unplug them (one at a time so you don’t lose track of what goes where), hit them with some contact cleaner, then plug/unplug/replug them a few times. Work your way through those and see if that fixes it.

I had molex dirtiness issues on a CS400 and M-3000 power amp. It might be more likely on units like that because of the fan pulling airborne junk through the chassis, but if you have it open anyway it can’t hurt to check.
 

j0Nasty5150

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Joined
Dec 14, 2021
Posts
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Age
63
Location
Cleveland
Thanks for the detailed response! I'll check everything in the comments. I saw those white connectors on the PCB, but I was skeptical about messing with them as I wasn't sure if they came apart and didn't want to break anything! I like these Solo Series amps!
 




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