Noisy pots and switches!

Noisy pots and switches, what's your favourite cure?

Just about every tech I've talked to has their favourite technique or product. The problem effects all of us sooner or latter and it has far worse effects than selecting the wrong bias current.

Originally I used lightweight lubricants but after a year or so they evaporate and leave waxes behind that made the situation worse. Now after trying numerous techniques I've settled on giving the pots/switches a good exercising and a light aplication contact grease supplied by RS Components, (the supply of which has dried up).

The best pots that I have come accross were in an English mixer, the slider moved a magnet over read switches. I never had to attend to them in 15yrs. One day I'll make one of these.

Regards WALKER
 
Well, if you HAVE to clean them :) use an electronics contact cleaner... these are found on Radio Shacks and similars as a spray with a long nozzle; and removes oxide, grease and dirt without leaving residues after evaporating. I've used a cleaner like this made by a local company ( http://www.edelta.com.ar ) to clean some RCA contacts once and worked great. To clean the pot, you just spray inside, give it a few turns and you're go.

For the record, i'm trying not to use pots if they're subject to a lot of use. For example, the volume control on my preamp will be a small motor interfaced to perform as a rotary encoder and drive the volume digitally. On EQ and other parts where they're less used, it's ok for me.
 

remp

Disabled Account
2001-11-13 5:19 am
New Zealand
Using WD40 does sound a bit rugged for cleaning pots and I was very dubious when told about it years ago but it does work. I have tried out different types of "proper" electronics cleaning fluids for cleaning pots and found them not as effective. There must be something in WD40 that does the job. Info only offered after many years cleaning all manner of pots with surprisingly good results.
 
Remp, I have also tried WD40, years ago, (I suppose that it could be a different formula now days). It seemed to evaporate after about 12 months leaving a waxy deposit. I used to work at a radio station, the mixer pots used to continuously cause problems.
Thanks for the suggestion I might give it another try on some less critical pots.

Regards WALKER
 
Noisy Switches and POTS

When you are talking about noisy switches we have to consider what types they are before a good method of cleaning can be discussed.

Many push type switches can be disassembled for cleaning when proper care is taken. Caution must be used since these switches may have sliding contacts that are not all the all the same within the switch assembly. I have restored many switches on old equipment in this manner and oxidation can quite easily be removed completely. I have done this mostly for individuals who love their old equipment and do not want to part with it.

If care is taken nothing will break. It is really nice to have various old switches laying around for parts in case you loose or bend a sliding contact.

Once the switch is apart different contact cleaners and polishing compounds can be used. After cleaning a light lubricating type contact restorer can be applied to the contact area to help fight oxidation in the future.

A word of caution: Care must be used when using any type of spray solvent or cleaner. Some will dissolve older plastics and perhaps some newer plastics and after the solvents evaporate parts may glue themselves together. Thus the switch may become totally useable.

For rotary switches contact restoring lubricating type cleaners can be quite effective. There is usually no way to take apart a rotary switch for cleaning.

Many older switches have silver contacts and usually have a very dark coating present were the contacts are closest to the air on the outside of the switch assembly. The dirtier our air gets the worse the switches are.

Again a word of caution: Care must be used when using any type of spray solvent or cleaner. Some will dissolve older plastics and perhaps some newer plastics and after the solvents dry. Thus the switch may become totally useable or glue itself together. Dissolved plastic will also leave a coating on the switch contacts even if the switch still rotates or pushes in and releases properly.

There is really no helper for pots that lasts a real long time. Lubricating contact cleaners will last for perhaps several years if the pot is good generally good condition. Months if it is not. The best thing is to replace these if at all possible.

There is just no easy solution for any of these problems. Some times the best thing to do is to replace the equipment.

John Fassotte
Alaskan Audio

[Edited by alaskanaudio on 11-22-2001 at 06:03 AM]
 
John, thanks for the benefit of your experience, you mentioned a “light lubricating type contact restorer” could you tell me the brands that you have found that work best? I’ve been using a contact grease from the UK supplier RS Components, unfortunately they no longer sell it. I have been using it for over 10 years now with remarkable success and (not one need for re-treatment in that time). The tube ran dry and I’m looking for a substitute.

I have procured some Nye potentiometer gel, (http://www.nyelubricants.com/automotive/DS-PDF/800-ds/813S-1.pdf) not cheap and it will take at lest 12 months before I can ascertain it’s effectiveness. Has anyone used this product before?

I also bought some Nye Rheolube 737s sliding contact grease, again does anyone have experience with this?

I use a fibreglass eraser pen (the type draftsmen used to use on Indian ink) to clean oxides off contacts and pot tracks. It’s very gentle and doesn’t appear to remove any plating. A light smear with the magic goo has, in the past been a permanent end to noisy switches and pots. My customers have never complained and yes they do come back.

Hope this could be of help to others,
Regards WALKER
 
Walker,

I have not used any of these types of cleaners for quite a number of years. It seems to my that I had used the Chemtronics "Kontact restorer" with good success on a good number of parts. Perhaps this link will help they have products designed for various areas of the work. I suppose due to different regulations.

http://www.chemtronics.com

The other one I used before, and I can't remember the exact spelling is called (more or less) "cramalon". Perhaps someone else can come up with the correct spelling. They have various different types of things avalable that come in small bottles and are actually quite expensive but very good. These are not spray type products.

I dislike using sprays on assembled equipment since these also coat circuit boards with oils and other unsightly residues. Then these also need to be cleaned by some method.

More times than not I was forced forced to use what was available locally.

John Fassotte
Alaskan Audio
 
In general, the idea is that any DC flowing through switches and pots is one of the major sources for creating pits and contact failure. As already mentioned, the only way to get rid of the problem, is to change the part.

Contacts can be cleaned, preferrably in two steps,- first with a contact cleanes that evaporates totally, to loosen the dirt, and then with a cleaner which contains some light oil, generally recommended for moving parts as switches, pots etc.
This will probably cure the problem, - at least for some time, but noisy pots will get back to old habits,- in most cases. WD40 contains a.o. graphite, and I would not use this for switches etc. It is though one of the best friction reducers in light form. One of the best for squeeking hinges....

For switches, connectors etc. that are silver plated, I have used the silver jewellery dip cleaners with excellent result. This does of course necessitate the part to be removed from the equipment.Thorough cleaning in warm water, and then contact cleaner is very important, to get away the residues of the usually rather reactive silver cleaner.

Good luck.