Episode: 2759
Title: HPR2759: Cleaning the Potentiometers on a Peavey Bandit 65
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2759/hpr2759.mp3
Transcribed: 2025-10-19 16:26:51

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This is HBR episode 2007 159 entitled Cleaning the Potentiometer on a Beavey Bandit 65.
It is hosted by John Kulp and is about 21 minutes long and carries a clean flag.
The summary is, I disassemble and clean the pots on my Beavey Bandit 65 to fix static in the knob.
This episode of HBR is brought to you by AnanasThost.com.
Get 15% discount on all shared hosting with the offer code HBR15. That's HBR15.
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Hey everybody, this is John Kulp in Lafayette, Louisiana and I wasn't really
planning on doing an HBR episode today, but I thought what the heck I might as well,
because I was about to start on something that might be of interest to hackers.
I have here an old guitar amplifier. This is a PV bandit 65 that I got new in about 1986 or so.
At the time, it was a decent amp, not a great amp. It's solid state, so it's not a two-bamp,
which is for electric guitar players, two-bamplifiers are normally the ones that they really want,
but they cost a lot more, at least they did at the time.
The reason I'm going to work on it today is to try to get rid of some of the static in the
potentiometers, also known as pots. Also, I was really hoping, just by cleaning it up a little,
I might make the saturation work again. Those of you unfamiliar with PV guitar amps of the 80s,
the saturation knob is the one that gave you distortion. I got this amp out again recently,
because my daughter was interested in playing my guitar and I hadn't played it in ages. The amp
had not really been used in 20 or 30 years, and it seems like the saturation doesn't work. I'm
not getting any kind of distortion anymore, and so I don't know if cleaning is going to fix it,
but that's always the first step. I watched a video earlier today on how to clean the pots on these
things, which is a little different than the way I had done before. I think I tried cleaning them
before by just pulling the knob off and then spraying contact cleaner in there from the front,
and then putting the knob back on. That might have helped a little bit. Some of the knobs are kind
of sticky. Even if they're not making static, they're a little sticky. I'm going to turn the amp on
now without a guitar plugged in. You might be able to hear the reverb. I guess I have the reverb
switched on. I left the foot switch downstairs so I can't switch it back off.
The lead gain knob turns it up where you can probably hear that. That's just like the sound of
nothing. I'm turning the saturation knob now. It's very tight and sticky. There's the post gain.
You can hear it's got static. The normal gain, let's see.
On the equalizer, low range seems not static, but it's very sticky. Mid-range turns pretty well.
High turns really well. It pulls just fine. No static. There's a presence knob. I'm not sure what
I have to get the manual out again to understand what some of these things are supposed to do. The
master reverb also is kind of static. I'm hoping by cleaning these out that I can get rid of the
static. I'm going to turn it back off now. I'm going to turn the amp around a little bit this way.
I think I'll take a couple of pictures while I'm at this. The band at 65 is a classic amp.
From what I was reading online today, you can still get. If you want to buy a band at 65 from
the mid-80s, you might end up paying a couple hundred bucks, which seems like a lot for a 35-30
some-year-old amp, but maybe it's because it holds its value. Here's a picture from the front.
And I'll take a picture from the back. I was going to take a picture from the back anyway to make
sure I got the speaker wires back on in the right order. I see here that I bought this amplifier
at Tuskyl and Music Incorporated. I remember the store very well. That was on No One's Feel Road in
Nashville, Tennessee. And I remember Mr. Richard the owner and also the guitar instructor that I
studied with was named Richard. Got named Richard Downs. He was a very successful studio musician in
Nashville. And he is one of the people who I credit with getting me on my way to being ready to
study guitar in college and eventually have a career in music. So I have very fond memories of
Tuskyl and Music. And I don't know if it's still there or not. It'd be nice if it were, but I guess
one doesn't know these things. So the first thing I'm going to do is there's a connector for the
reverb panel up here that I need to pull off ever so gently. Is there any clips or anything? I don't
I don't feel any clips. Oh, there it comes. Okay, I got it off. So the reverb is disconnected.
All right, now I need to disconnect the speaker wires. Yellow on the left and blue on the right.
Okay, there's one. I don't think these have ever been taken off the speaker.
Okay, both of them are off now. I was harder than I wanted it to be. All right, so I've disconnected
everything. And now what I need to do is get the circuitry part out. And so to do that, I have to
undo four screws on the top of the amp. I'll try to take a picture of this as well.
Okay, taking these screws out. I did the same operation just a little while ago on another amplifier I
have that is much less valuable to me. It's a little audition chorus, chorus audition or something.
It's another PB amp, but I got it at Goodwill for 13 bucks, not that long ago.
And so I thought I would try it on that first. And it seemed to go, okay, I'm not sure it helped
a whole lot. I didn't take a lot of time testing beforehand to see which knobs were static in which
ones weren't. So the guy recommended not to take all of these out all the way, but to loosen them almost
all the way. And then just be sure to support the thing so it doesn't go falling down. Okay,
it's wedged in there pretty tight. So I don't think it's going to fall. All right, it's
the screws are all out. Oh, this is quite come out easier than the last one did. I'm gently pulling
from the back and pushing from the front to try to get the brains of this thing out. Okay, it's loose now.
This must be exciting to listen to. Is there another screw hook? No, there's not.
That's definitely all the screws. It's just wedged in there nice and snug, which you want. I mean,
this is a build quality thing. One of the things that the guy in the video I watched pointed out was
that these amps were all made in the United States in Meridian, Mississippi. In fact, I've seen the
PV factory there when you drive through Meridian, which we do with some regularity because that's
halfway between Lafayette, Louisiana, and where my parents live up in middle Tennessee.
And also when you fly in the old days, when you flew from Lafayette, Louisiana to Atlanta on one of
those propeller planes, you had to make a stop in Meridian, Mississippi to pick up usually military
folks because there's a base there. But you could see the PV factory from the runway. That always
used to please me. Ah, there we go. There we go. One of the screws was still just a little bit
as an outsliding right out. Okay, good deal. There we go. Okay, the circuitry is out now.
So what I'm going to be doing is taking some contact cleaner and spraying it into each of the
potentiometers or pots and then vigorously moving the pot back and forth. And if it's got a pull
mechanism pulling that out and just making sure it gets all around in there real good.
So spraying some cleaner.
Some of these have little holes at the bottom where the guy on the other video is I'm going to put
this on its face, I think. Work and get it these holes a little easier. I'm going to do the next one now.
This contact cleaner is meant to evaporate. I can feel that loosening up already. That was one of the
tight ones. That one is definitely loosening up a bit. Maybe I'll pull this knob off.
These kind of knobs you can pull them straight off. And then I'm going to spray from the front side.
Put them all back on. I made sure to have the indicator pointing exactly up at the five before
I took it off. So I know where it went back. I'm going to push it back on and then go back with the
back and forth motion.
You can definitely feel these things loosening up once the cleaner gets in there.
Hopefully that means they will move freely. Which one of these was saturation? It was that
second one I did. That still feels a little bit tight. It's better, but let's try a little bit more in there.
Go down to this one. Got a few more of these to do.
There's a very sticky one.
Loosened up considerably with some lubrication. That's because it's not lubrication. It's just cleaner.
One of these things needs lubrication as well. Again, the video said not to put any WD-40 or anything
like that on them. So I'm not doing that. It doesn't seem like a good idea to put WD-40 on electronics.
I guess if all else fails, I could get a distortion pedal if I really want distortion in the amp
or I could have a professional try to fix the saturation circuit if that's what's wrong with it.
That one is... that's not the reverb. This was the presence knob. That was pretty sticky as well.
I'm going to squirt some more down in there.
Since this stuff evaporates, I don't guess you can really spray too much.
Now the reverb one. This one's sticky. Yeah, it's very sticky and it's static-y as well.
Let's put a bunch of contact cleaner in there. It seems to get right down in there.
Yeah, it loosens right up.
I guess this could be tested as well. It's still a part like this, but I don't really want to
plug it in while I've got it all sitting out on the table. It seems like a hazard.
So I'm not going to do that. Check all these one more time.
The reverb still seems a little bit sticky. I'll pull that one off and go from the front.
Saturation still feels sticky. I get the idea that this stuff is not exactly a lubricant.
It feels a lot freer while it's drying, but then once it's dry, it still feels a little bit sticky again.
Okay, well, maybe it's time to put it back together.
I turn the volume ones all the way down to zero, just to avoid any big surprises when I turn the
thing on. And so what I'll do is I'll gently ease this thing in there and then try to start the
screws.
There's so much trick to it. Okay, there we go.
You can get the first one in. The others should easily follow.
There we go. That one's starting to thread.
Three of the four screws are in now and now the fourth one.
I think I'm going to reattach the speaker where I was before. I put this supporting bar back on.
I know. Okay, yellow and blue.
All right. The speaker wires are in place. I'm not going to test this before putting the last
piece back on because if what I did did not help, then I'm just going to live with it.
I'm not going to take it back apart and try again. It's not that important to me.
Just a fun Saturday morning thing to do.
This makes for good radio, doesn't it? Listening people screw in screws.
Even better than when you're waiting for people to screw in screws on one of those how-to videos.
All right, let's give this a try now.
Go ahead and put on the floor so it reaches the out a little bit easier.
Well, the reverb pot no longer makes static. That's good.
Which other one made static, I forget.
Reverb sounds nice and clean.
They all sound clean now. I don't hear any static.
Saturation still feels a little sticky, but should I plug a guitar into it? What do you guys think?
So now I'm getting out my guitar. This is a 1977 Fender Stratocaster.
The effects pedal goes on the floor and then you got to plug it into a quarter-inch plug in the back
of the amp labeled foot switch.
Good.
That made a lot of noise when I plugged in the, okay.
The effect, I guess the effects were switched on on the pedal.
Okay, now, picture of the guitar.
Maybe one day I'll tell the story of the provenance of this guitar. It's actually a pretty
interesting story, but that's for another day. But this is actually an American made Fender too.
Okay. I've got the guitar around my neck now. I wish I could take a selfie with the
guitar like this. Then you guys could see me rocking out. Oh man, I forgot to bring a guitar
pick up here. What a dope. So a little bit of volume on the guitar.
Do-do-do-do-do-do-do-do. I've never tried to play this hum guitar before.
Okay, let's see if I get any saturation.
Yeah, a little bit.
I can't play the guitar like I used to when I was young because my hands aren't as good anymore.
I think it might have fixed it.
Man, this is out of tune.
Wait, where is it?
Okay, well, anyway, it seems like the saturation is working now.
And it wasn't before, so maybe I fixed it.
I certainly hope so.
That will make it a lot more fun to rock out if I get some distortion.
I guess that's probably about it.
This has been John Culp for Hacker Public Radio.
And I will talk to you guys again soon, I guess.
Okay, bye-bye.
Okay, so after getting my amplifier back downstairs and getting it set up
and getting the foot pedal pushed in, I kind of realized something.
I think the reason I was not getting saturation distortion
before was that somehow my amplifier had gotten stuck on the clean channel.
And I had forgotten about how the amp operates.
The foot pedal has two switches on it, one switches on the reverb,
and the other switches between the effects channel and the clean channel.
I think it had gotten stuck on the clean channel.
Of course, if that happens, then no matter what I do to the saturation,
it doesn't make a difference because that's on the effects channel.
So anyway, now I know.
But I think it was still helpful to clean out the pots using the contact cleaner
because I did get rid of the static that you get when turning them.
And of course, it's fun to take stuff apart and put it back together.
So there's that.
Anyway, that's it for now.
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