Instructables
Picture of How To Clean The Controls On Your Amplifier
Is that crackling and popping when you turn the controls on your amp driving you crazy?  Here's how to clean them and get back to the music.

There are spray "contact cleaners" available for this purpose, but in most cases just mixes the dirt and grime already inside with more dirt and assembly grease and may make the control operate worse than it is already.
 
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Step 1: Remove mounting knobs and nuts

Picture of Remove mounting knobs and nuts
The first step is to remove the knobs and nuts mounting the controls to the front panel to the amplifier.  Remember to keep all the parts sorted so you can find them later.

Step 2: Unsolder the controls

Picture of Unsolder the controls
After the circuit board is removed from the amplifier box, each control is removed and cleaned one part at a time.  Do not take them all off at the same time, because you may mix them up.

Step 3: Remove old solder

Picture of Remove old solder
Remove old solder and inspect the pads for any burnt or broken traces. 

Step 4: Open the control

Picture of Open the control
Open the control (potentiometer or "pot") by lifting the mounting tabs slightly.  Remember that these tabs will not handle being bent more than a few times before they break off.  If a tab breaks off, you may be able to solder it back on later.

Step 5: Inspect dirty contacts

Picture of Inspect dirty contacts
The control is made up of two main parts.  The contacts and the carbon resistor.  Each side must be cleaned without damaging them further.  If the carbon looks burnt or has broken areas, the entire control may need to be replaced.  If the contacts are worn too much or broken, the entire control may need to be replaced.

Step 6: Cleaning

Picture of Cleaning
Carefully, clean the contacts and carbon with a pencil eraser.  Do not push too hard, and clean the eraser on a piece of paper when it gets too dirty.  Do not use any cleaner or solvent except rubbing alcohol or cleaner designated for this type of control.  Make sure to blow off any eraser particles left on the control before assembling the part.

Step 7: Cleaning continued

Picture of Cleaning continued
If you are cleaning a dual control, the method will be the same, however it will take twice as long, and you must align both controls so they go back together correctly.
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An eraser is a cheap and easy way to fix it sometimes. This was is great if you have a cheaper amp however if you have something that is vintage and high dollar. I would exercise the knob with some electro wash (I believe this is a 3M product). Follow this will a ultrasonic bath for 24 hours then dry for 24 hrs. If this doesn't fix it a new pot would be the answer.

Lenny243 years ago
This step may change the resistance or the wattage of the potentiometer.
So be careful you dont do this too often
Teslaphonics (author)  Lenny243 years ago
That's true, I've seen some people "clean" pots with sandpaper. They don't work at all after the carbon is removed from the phenolic backing.
Sandpaper has no place in contact-cleaning when it comes to electronics....Electrical sometimes, but not electronics. "Carbon Tracks" (such as those laid on phenolic for radial and linear varistors) should never be cleaned with an abrasive. The surface itself MUST be smooth for "noiseless" operation. A soft cloth and solvent can be used, but not sandpaper (O_o).

If they are using things like sandpaper on it, then you need to take it away, as well as any sharp objects, before someone or something gets injured. As said below; if a blast of "TV tuner cleaner/lube" or similar product, followed by moving it through it's range-of-motion several times does not solve the "scratchy pot", then just replace it, as the brush or substrate may simply be worn-out.

Automatically replace it if the maximum resistance is not within 10% of it's rating (or 5% for motor speed-controls and non-television audio equipment is my standard). If there is a lot of "play" in the shaft of a radial varistor (indicating wear), just replace it.

Sandpaper will work just fine for "cleaning" contacts.

The only thing you need to do is use high grit sand paper...say 600 to 1000 grade or higher depending on how sensitive the components are.

That pencil eraser he is using has the same effect on the carbon that sandpaper does...it smoothly removes layers of existing material.

Would methalyted spirits (denatured alcohol) work for cleaning contacts? :)
That's one of the things it was made for, it's just not as strong a solvent, you you might have to work a little more at it, but that would be the second-best thing. In the case of a potentiometer or similar sliding contact, you want some lubrication that won't interfere with the electrical properties.

For cleaning contacts like nintendo cartridges or audio jacks, etc., denatured alcohol is perfect.
camogreen1 year ago
The tech would have used some spray and charged for an hour's labor. At the same time this technique may be considered overkill but will certainly work well. Good job and now many people know what is inside a pot.
fizzard2 years ago
This is brilliant. I have a MusicMan amp that has been going loud/soft/fuzzy intermittent for ages.

I followed your instructions and dared to take it apart to clean the volume pot.
Now I have a new amp!

Thank you for your superb clear instructions and pix.

Now how did Stairway to Heaven go? (only jokjng!)

Cheers,

Myles
djjoec2 years ago

I was wondering if I could use this same technique with the nobs on my numark mixer as Im a Wedding DJ in Melbourne. And my mixer  makes crackling noise when I raise the volume. If anyone can recomend a product that would be great and save me from buying a new mixer. Cheers
Slightly off topic but - Awesome Photography! What equipment are you using? Especially for the lighting, are you using a ring flash? It doesn't quite look like it but the results you get are great.
molbar3 years ago
be here in new zealand i use a product called selley's rp7 just spray it in work controls a few times and job done and it is safe to use on electrical and electonical equipment
hlee tech3 years ago
one thing i learned years ago is not to use WD40 for many things that it seems successful at .. i had a big daven switch that never worked again after a clean and lube with wd40 .. i had a gorgeous selectric typewriter that become so gummed up that it never worked again. i was in a big airline and we had to make an emergency landing. the tail gate was indicating that it was open in flight. it turned out that the tech had been using WD 40 to clean the micro switches. after a while they gum up and quit working. we used to have really good control cleaner that included a lube. but recent stuff had to be reformulated for some reason. i cleaned a bunch of stuff with the new formula and they all quit working. turns out whatever it is, was causing delamination of the control resistance film. it was dissolving the adhesive that holds it together. yikes .. that was expensive. its best to use a product that is known to work like Deoxit . and to be really cautious of reformulations. i called the WD40 people years ago to find out why the failures. they said "its not intended for that service" the results will be unpredictable". i understand its fish oil and it does a nice job of displacing water. but not necessarily all the other things its become known for. often it seems to work great for awhile but can cause lots of trouble. its lubricating properties are not easily penetrated by switch contacts and sliders in pots once it has lost its evaporate. then it seems to get sticky (gummy) after a while and hard to remove.
Dr. Science3 years ago
Deoxit it is a great product and I'm not taking anything away from it's quality. Please don't laugh at me until you've actually tried this though: instead of Deoxit, try spraying WD-40 on the pot or switch. This solution has worked great for me, also. WD-40 will not conduct electricity so one can use it in real time, is long lasting (I've sprayed guitar amps, pro gear, and even AC switches with excellent results). No joke. -the doctor is now in.
JONNY+QUEST+DR+QUEST+SKETCH+CARD.jpg
Before going through the trouble of taking apart your amp or spraying anything in it take a few minutes to "exercise" your pots. If you take the time to observe where your problem areas are you'll often find that the ranges of your pots that you don't use often are the areas with the problems.

"Exercising" you pots means to periodically run the pot back and forth through the entire range of motion so that oxidation has less of a chance to take hold in any given area. Indeed, you can even "exercise" a scratchy area completely out of existence with this method. I resurrected a rather expensive fender amp ( and got a deal in the bargain ) with a complete set of scratchy pots by turning it on, playing a tone through it, and then running the pots back and forth until the scratchiness went away.

Basically the wiper in the pot abrades away surface oxidation that causes scratchiness. This is fine for your amp because these pots are designed for thousands of turns through the course of their lifetime.
richarpo3 years ago
Would be tempting to replace the potentiometers, if they did not cost too much. Fantastic pictures, they are crystal clear.
mwseniff3 years ago
Deoxit by Caig is definitely the way to go. I have been working in electronics for 30+ years and it is hands down the best product out there. It contains a high molecular weight paraffin that leaves a molecule thick layer over the metal surfaces which protects them from further oxidation. When the contact is moved it displaces the film temporarily allow the contact to do it's job then reforms behind it, It also increases the conductivity (some manufacturers use a paste form of this to increase current rating of switches as it also stops arcing). I find that I rarely need to disassemble a pot after using this magic spray. There are also varieties that include lubricants for use in slider controls. You also need to be aware that many products contain solvents that flush away all the lubricants in controls and this can be a big problem in sliders. I have used Deox-it and it's kin (Preserve-it, as well as the gold variety) on everything from old guitar amps, mixing boards, chemistry instruments to flashlights with excellent results. Many years ago when I worked in a high end stereo shop I went over the connections of the distortion test gear with Caig products and lowered the loop distortion test readings by an order of 10. It is all I have used for the last 28 years including on my vintage guitar amps. It reduced potentiometer replacement to zero except when they were physically broken. I have found nothing else to compare to these Caig products and many so-called contact cleaners can damage controls so be careful. MCM Electronic is a good source for Caig online.

As an aside there are electronic problems that can cause pots to sound scratchy as well. Most commonly DC leaking on to the pot from a bad capacitor so that is worth checking to especially in old tube amps. Some modern guitar FX pedals exhibit these symptoms while working normally like some Zvex and other boutique distortions that use a pot to voltage starve the circuits but the pots are usually marked "crackle ok".
I heartily concur with De-Oxit. Our company uses it as a standard troubleshooting tool for intermittent electronic problems. Pull all the boards, spray the contacts and turn it back on. It works awesome!
Teslaphonics (author)  crusty knight3 years ago
Once again I say, there's no magic spray that will turn grease, scratches and dirt into pure gold and silver. Spraying a bad solder joint will not make it conductive again, spraying a cracked PCB trace will not fix it.
Agreed, however Deoxit will clean oxidation from contacts in harsher environments. I've used it to clean rust out of electromechanical clutches so I see no reason it wouldn't work to clean dust and crud out of the potentiometers; but you're right, broke is broke.
eddems mwseniff3 years ago
I really like Deoxit. I used it on tube strain gage amplifiers back in 1975. We couldn't get our amplifiers to stay at zero (microvolt measurements) unless we cleaned the gold plated edge connectors with it. In thwe ionstrumentation lab, we depended on it. I used it on TV cable connectors too, back in the analog days. Good stuff. And this was a great instructable.I didn't know anyone did work like this anymore. Outstanding..
dagnabbit3 years ago
I didn't see a disclaimer anywhere here- I want to add this for safety:
Especially for tube amps, and for any electronics using large capacitors and/or large power transformers in general... PLEASE BE CAREFUL. Discharge those capacitors first safely. Don't work with amps that are powered on. If you've never done this before, learn basic electrical safety first. Be safe! :-)
Scott_Tx3 years ago
that's a total cleaning! Something you could also try is something called Deoxit Gold. I've never used it but the people in the flashlight forums say its good for cleaning contacts and they stay cleaner longer afterwards.
Teslaphonics (author)  Scott_Tx3 years ago
I'm not familiar with that product, but I'll look into it. Sometimes if the contacts are silver or gold plated, I will use a tarnish remover first, then an alcohol wipe to keep from removing the thin plating. Not all contacts are made of the same materials, and you don't know until you take it apart.
Deoxit works great. There's two main products- the regular Deoxit and Deoxit Gold. Deoxit has way more cleaner in it. Deoxit Gold has less cleaner and is more about contact preservation (regular Deoxit does this as well). I use Deoxit on all my music gear contacts (jacks, plugs, XLR's, etc). I know it's also used for doing slider maintenance on mixing consoles- I'm in the process of refurbing a mixer right now and using my trusty Deoxit pen. I haven't used Deoxit Gold though, more interested in the cleaning function. I think a followup application of Deoxit Gold after using Deoxit for cleaning is a good idea- if I remember the web site correctly (but they're trying to sell product!). I think it's the gentlest checmical cleaner I've ever used (man, I remember WAY back in the day when we'd wash down huge circuit boards with Freon, best stuff ever- cleaned everything, reacted with nothing. Who knew it was bad for the environment?)
GitarGr83 years ago
Oh I love you instructables! I have an old Peavey amp that pretty much stopped working, and was about to throw it out. I'll give this a shot and maybe I won't have to buy a replacement. Thanks!
Thanks Teslaphonics! I have an old amp that I've tried everything (sprays and whatnot) short of taking the pots apart and nothing worked. Now that I see it's possible, I'm going to try your detailed method. Thanks again, friend.
Thanks for the great instructable. Photos are outstanding!

I'm currently going through the exercise of finding one of those one-of-a-kind pots with an unusual resistance, unknown taper, and attached AC switch for my old reverb unit--one of the best arguments there is for the method you so clearly show here, rather than "simply" replacing the pots.

I have used spray contact cleaner on my old Fender amp with mixed results--as I recall, the pots are not soldered to a PC board, so eliminating the de-soldering/re-soldering steps should make it a whole lot easier. I've also run across some pots that don't have much of an opening anywhere to spray in the cleaner, even with the little red straw.

Comments about the jack also seem right on target to me, also. The guy I bought my amp from said it had been in a basement (dampness) for a while and the jacks seemed "dirty", (noisy), so he "cleaned" them up by sticking in a fine rat-tail file into the jack holes !! (Takes all kinds). I'm trying to find some gold-plated replacements, if I can afford them, which should take care of any future worries about corrosion on the jack contact surfaces. I also need to deal with the "death-cap", which I might post as an instructable, if nobody else has yet.

Thanks for sharing this. I never thought about disassembling the pots, but it looks pretty do-able.
Bandaids3 years ago
I just used the contact cleaner i got at auto zone works just as well xD.. ecpt its for car
If you use too much contact cleaner, you can cause shorts.
Roland543 years ago
Maybe easier to replace the pots when you decided to remove them
fun2fix3 years ago
On this step: If you can afford a solder sucker (ie; Solder Pullit) It saves a lot of time. If done correctly, it will keep you from lifting pads and etches. It does a great job of evacuating the solder from a thru-hole. Using solder wick works great for surface mount components and some through-hole but you will end up leaving heat on the pads longer than needed. I use both and each do their job in the right places.

I wouldn't use the side-load ones, just the top-load ones like this one:

SOLSUCKER-S.JPG
Teslaphonics (author)  fun2fix3 years ago
Yes, I agree they work well also. My basic point is not to trust the old solder, and to inspect around the pads because you can't always see a crack in the trace at the edge of a pad.
Absolutely! If you don't have the luxury of an inspection light (with lens) or an eye loupe you have to use the best technique you have.

Another idea is to use q-tips (or paper towel) with 93% Isopropyl Alcohol
(off the shelf) to clean away the flux residue left over from desoldering. That
will help immensely in your visual inspection.

I used to fix Fender amps back in the 90's. The small solid-state practice amps
were notorious for "intermittent" connections at the board. They were used by
kids who's cords were proverbially short....
fun2fix fun2fix3 years ago
Since I can't re-edit what I said, You already mentioned the alcohol... :-)
fdmundo fun2fix3 years ago
I totally agree with fun2fix -- I never got the hang of solder wick and ruined many a PCB with it. Solder-suckers work consistently well for me. Just put a little container under the bench to catch the expelled solder when you "reload."

Also, a case can be made that it's a "greener" method since you're not using up and discarding copper wick. OK, it's a trivial amount, but still...
mmbutler3 years ago
If you're going to go all the way down inside the pots, I don't recommend using a regular pink rubber pencil eraser -- they can leave sulfur contamination behind. A better option is the tubular white eraser elements that are designed for use with some mechanical pencils like the Pentel Side FX.
Teslaphonics (author)  mmbutler3 years ago
That's an interesting point. I usually use the white ones on larger contacts like model train track rails because it's denser. I didn't know about the sulfur issue. Doing a quick internet search leads me to believe that all erasers may leave some chemical residues, so make sure to wipe off anything left behind. I've used small alcohol pads (or some alcohol on a q-tip) to clean up also.
uncle frogy3 years ago
If using a spray is not good enough and the pots are just too dirty and/or worn and scratched to need go through that much trouble I would just replace them with new ones which are not that expensive and have the advantage of having a much longer useful life.
in a pinch to get through the weekend would be an OK gamble but I would not want to rely on it to be a long term fix.
Murphy's law lives on stage
I repaired a power amp for a musician long thin wood shavings from a cut off saw had gotten in and under the slider it was more reliable to replace

good skill and patience
Teslaphonics (author)  uncle frogy3 years ago
These particular pots were heavily oxidized, but not all that worn. They also weren't marked as to linear vs audio taper and two had custom switches built into them - not easy to find unless you have the schematics and part numbers.
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