How to Clean the Controls on Your Amplifier

Intro: 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.

STEP 1: 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

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

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

STEP 4: 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

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

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

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.

STEP 8: After Cleaning - Reassemble the Control

Being careful not to forget any parts, recrimp the case making sure not to bend the case or trap any parts between the case and the parts inside.  Turn the control and check for a nice smooth motion from the 0 to 10 locations.  The control should move approx. 120 degrees without any binding or bumps.

If you think you assembled one incorrectly, set it aside, and open the next one to look at how it should be assembled to fix the last one.  If you need to, take pictures of each phase to help you reassemble the parts later.

Try not to get any grease or oil on the contacts while assembling the part.  There may be some grease on other areas of the control, but it is not intended to be on the contacts.  There is a special conductive grease that can be used on the contacts, but is not necessary for proper operation.

STEP 9: Resolder and Continue Cleaning the Rest of the Controls

Use new solder to assemble the clean control back onto the PCB.  Clean the solder flux off with some rubbing alcohol or flux remover.

STEP 10: Finish and Test

Put the PCB back into the cabinet, and test the amplifier.  Turn each control and make sure it works as it should.

That's all folks, enjoy your "good-as-new" amp.

It took me about 2 hour to clean this Peavy, so at a tech rate of $60 per hour, I saved a bunch of cash doing it myself.

Comments

[PorkieM]

Thanks very much for this. Simple and effective. This worked well for the input gain knob on my Trace Elliot. It got very scratchy and then finally I could get no output at all. It probably took me 10 passes with a clean eraser before the eraser did not pick up anymore carbon (clean). So be patient if you are doing this. Now I'm completely "scratch" free, after many years of ignoring it. I won't need to wait as long next time.

[gdesmarais]

For the hard to acces pot, go with perchloroethylene (PERK) found in brake cleaner. Take a spray tube from another bootle if the one you purchased didn't come with any. Then no need to dismantle and desolder anything. A good alternative is almost pure isopropyl alcohol. Avoid water content unless you can dry it or wipe it afterward.

[mail.stab5]

"For the hard to acces pot, go with perchloroethylene (PERK) found in brake cleaner."

That's the best way to go. Brake Clean cleans and dries grease, oil, etc... Just as an example, brake clean is used to diag oil leaks on cars. The bottom of a motor can be soaked in oil, and all you have to do is spray it with break clean, and it completely dries all the oil. No need to wipe anything down, or do anything else. It works as long at you can get it on whatever you need to clean.

An alcohol based cleaner can damage anything like plastic, wire dielectric, water born acrylic/latex paint, or similar materials.

Mineral spirits is not a good choice either. It can also harm certain materials, and has a strong odor.

[LarryS9]

Nice job detailing the steps. Here is an easy method that I use. as always, make sure power is unpligged. If you can get to the pot don't bother unsoldering the pot. If not remove it. Use canned air with the thin straw that it comes with and point the straw at the base of the legs of the pot and blow air up and through the pot. Safety Warning for the next step. Don't spray your fingers. You will get frostbite. it will be very cold. Turn the canned air can upside down and spray into the pot again. the stuff in the canned air comes out as a liquid when you do that. It will vaporize in the pot. Turn the pot back and forth a bunch while it warms up. It may be stiff while you do this. Don't force it if it is too stiff. Wait a bit. As it warms up it will get easier and easier to turn. once it is easy as normal to turn you are done. I usually give it 5 minutes after that before powering on. That stuff evaporates pretty quickly

[douglas.bischoff1]

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.

[Lenny24]

This step may change the resistance or the wattage of the potentiometer.
So be careful you dont do this too often

[Teslaphonics]

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.

[Prometheus]

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.

[Cancer Ridden Lung]

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.

[Callum Snowden]

Would methalyted spirits (denatured alcohol) work for cleaning contacts? :)

[Prometheus]

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.

[camogreen]

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.

[fizzard]

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

[djjoec]

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

[nonobadog]

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.

[molbar]

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 tech]

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. Science]

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.

[ejensen99999]

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.

[richarpo]

Would be tempting to replace the potentiometers, if they did not cost too much. Fantastic pictures, they are crystal clear.