Noisy pots and switches!

[walker]

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

[Lisandro_P]

The only real cure for a noisy pot/switch that i'm aware is a replacement Even a $1,50 pot will outperform a noisy one that's been "cleaned".

[walker]

Lisandro_P I can't agree with you more, unfortunately that's not always an option.

Regards WALKER

[Lisandro_P]

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]

WD40 works great for cleaning noisy pots. Dont use too much just a very small amount. Dust and dirt can get into pots and the cleaning works. If they are worn in one spot from constant use, replacement is the only real cure.

[cp642]

remp,

WD40 for noisy pots?? Oils attracts dirt and dust you might end up making it worst. should try out a proper contact cleaner.As for replacement, I must agree that it's the only cure for noisy pots as it's caused by worn out contacts.

[remp]

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.

[cp642]

Scratchy sounds are caused oxide dusts accumulation at the pot contacts. The reason you can't hear it after WD40 application is this dusts gets wet down by the oil and are brushed aside. This something similar to vinyl record cleaning.

[walker]

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

[alaskanaudio]

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]