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SemiHollowGuy

Best way to clean amp pots

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Just picked up a couple of 80's vintage guitar combo amps: a Dean Markley RM-80-DR and a Yamaha G50-112. Several of the pots are "scratchy" on both amps. Other than the obvious (remove amp from cabinet) what is the best way to clean the various pots? And what is a good cleaner to use?

 

TIA

 

Michael

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I bought a can of De-Oxit not too long ago, and it has worked very well for me. I think removing the chassis from the cabinet is by far the best way, though I have had some success spraying it on the shaft. I like to use a cloth or napkin to catch the overspray.

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Thx. I ordered Deoxit, and it's 2 other Deoxit products (one's a pot lube, etc) and they should be here the end of the wk. Certainly I was planning on pulling the chassis and opening it up to really get at the pots.

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Thx. I ordered Deoxit' date=' and it's 2 other Deoxit products (one's a pot lube, etc) and they should be here the end of the wk. Certainly I was planning on pulling the chassis and opening it up to really get at the pots.[/quote']

 

DeOxit is wonderful stuff. Make sure you unplug the amp and leave it unplugged for a day or two to let the caps discharge before you open it up. Better yet, learn how to safely discharge your amp's filter caps and do so after leaving the amp unplugged for a day or two. Safety first!

 

I don't recommend trying to spray it into the shafts from the front. Open the amp up and spray into the holes in the sides of the pots while simultaneously rotating them through their full range of rotation. Let everything dry for a few hours before you button it all back up.

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The DeOxit Gold arrived yesterday and the DeOxit D5S5 (the contact cleaner) and F5S-H6 (Fader Lube) arrive on Friday (thk u Amazon) I took the entire amp apart today to discharge caps and to clean up the cabinet, etc. I'll try to follow up after I'm done.

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I don't recommend spraying it into the shafts from the front, either, but I tried it once (didn't have time to take the chassis out) and it worked that time. I'm pretty sure that it would not work on more modern pots than the 60s-vintage pots on that amp.

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Cleaned a pot today.

 

Background: a while back, I blew out the tuner on my receiver. In order to have a radio, I hijacked my wife's portable boom box, and wired a cord from the headphone output to a high efficiency high fidelity speaker. Worked okay. At one point, she mentioned her old table radio. We used to use it, but it reached a point where the volume control was so scratchy that it was practically useless. I always figured that a good cleaning was all it needed, but it's been on a shelf, unused, for some twelve or fifteen years. And when I say old table radio, I mean old. She's had it since 1972. It's an Emerson. Good unit, back in the day.

 

So I dug it out and fired it up. Bad volume pot. On/Off switch is ganged with the volume pot, so there's no way to set the volume and forget it. Took off the back and sprayed it with DeOxit, and cleaned it right up. The bass control needed a shot, too. As old as it is, I wasn't sure how well a mere cleaning would work, but it worked very well indeed. Then I drilled a hole in the back and installed a speaker out jack. Sounds okay with its original speaker, if a bit heavy on the low mids. About what one might expect from a table radio speaker, but it's an AlNiCo driver. Maybe a mini guitar speaker? But it sounds really good through the hi-fi speaker. Distinctly better than the boom box, and the tuner is much better, too. Even the wood tone cabinet looks better. A win on every level. Looks better, sounds better, easier to tune in a station, louder and lower distortion.

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So the DeOxit products arrived and I got to cleaning all the pots. Got the amp apart pretty easily and went at the pots with the DeOxit D5. Put everything back together and all the pots are completely SILENT! Problems rectified. All is good!

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Glad it worked out for you. Happy New(ly silent) Pots Day. A while back, I was doing a setup on a friend's Ibanez electric guitar and one of the pots (tone, IIRC) was scratchy. I tried cleaning it but, honestly, I was ready to replace it. After a good cleaning, it worked like a charm.

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As a tech I've used a number of different cleaners, mostly industrial stuff. Chemtrol, CRC, MG, LPS are all real popular in the electronics industry and just as good as Deoxit. You can look up the EPA datasheets on them and see they all use the same chemicals depending on the type of contact cleaner it is. Deoxit has become very over priced now and the chemicals aren't any better then others. You can buy it on line but they sell for triple the price of what our company pays. We buy it by the case from our supply vendors and get better deals then most would.

 

There are three main types of contact cleaners. Zero residue is simply alcohol. Its a degreaser and removes dirt. It should never be used on pots or your problems will get much worse. Zero residue is used for switches only never for pots or your problem will get much worse. You can clean a pot first with the residue if the pots really dirty then use the lubricating contact cleaner.

 

Pot cleaners have lubricants, either silicone or mineral oil. Both work very well but they are used for different applications. Silicone is better for Dry pots that don't use contact grease to give them that smooth resistive feel when you turn them. You usually find those kinds of pots in Hi Fi stuff. Most guitar pots should be dry pots. Some mixer and amp pots like the old Tapco mixers were packed with conductive grease. You don't want to use silicone cleaner on those. I did it once and it froze the pots up completely. I had a hell of a time flushing them out and getting petroleum lubricants to work. Silicone does dry quickly and prevents moisture.

 

The other uses mineral oil as a lubricant. Mineral oil can creep over circuit boards and attract dust. You may wind up having to use it more and more often till the pots need replacement. I like it because it can often make very worn pots functional for awhile. The trick to using it is to get the spray in the pot and minimize getting it on circuit boards. You can use the mineral oil stuff on dry pots but many will develop schlock issues. When it eventually does dry the pot can wind up feeling glitch and feels like it gets stuck when you turn it. Those pots should have used the silicone based cleaner.

 

Its probably too late at that point to switch unless you disassemble the pots and clean the shafts to get rid of all the oil residue. I've done it before but I had to learn the hard way which chemical should be used for which situation. There's always exceptions too. Some pots can take either and still work pretty good. With dry metal shaft pots I usually use the mineral oil. With plastic shafts I usually use the silicone and they will tend to work properly.

 

Sliders on mixers will usually do better with silicone. If you use mineral oil you can often wind up having the sliders sease up on you. They have plastic pads inside and use a silicone paste to make them slide nicely. If you use mineral oil those pads can begin to grab badly.

 

Both will lubricate the carbon pads to make the scratchiness go away, bit its the mechanical operation that will suffer if you use the wrong stuff.

Guitar amps are pretty simple. If there's no resistance when you turn the pots, then they are dry. Pull an knob off and see if the shaft is metal or plastic.

 

I'm noty real sure but I think some Yamaha amps had grease packed in them to make the cheap pots feel good (and old trick of the trade) The Deoxit is mineral oil based I believe so giving them a quick shot should be OK. If they become sticky when turning, the pots should be taken apart and repacked with conductive grease. Its not a fun job because they are likely PC mount pots and require pulling the board completely out. If you're going that far it may be better to just replace them and be done with it.

 

 

Oh and there a few contact cleaners you should never use on audio gear. Some of its corrosive for cleaning metal contact and will eat right through a pots thing carbon pad. Always read the label and if you still aren't sure, don't use it because you'll probably cause more harm then good.

 

Never used WD40 either. WD is simply a moisture inhibitor used to prevent rust. When it dries it becomes an electrical inhibitor so your problems come back with a vengeance in a very short time except you have reduced the carbon pad thickness drastically. WD does make some contact cleaners now, but I haven't seen any specifically for pots yet.

Edited by WRGKMC

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