Sprays and other to clean switches and potentiometers - Page 1
Forum section: electronics / repair

author: JoeyG
author_rank: Regular Contributor
timestamp: February 03, 2024, 08:53:48 am
content: In Australia what sprays and cleaner chemicals are suggested to clean switches and pots.Device is an older Tektronix CRO.isopropyl for switches ?Jaycar had switch cleaner, but nothing for pots?

author: David Hess
author_rank: Super Contributor
timestamp: February 04, 2024, 01:32:49 am
content: Sliding switches must be lubricated after being cleaned. Potentiometers should be lubricated after cleaning also.I like this stuff because it has no silicones, but I do not know if it is available in Australia:https://mgchemicals.com/products/electronics-maintenance/contact-cleaners/electrical-contact-cleaner-spray/

author: Whitefoot
author_rank: Contributor
timestamp: February 04, 2024, 08:51:23 pm
content: I like MG Chemicals 404B contact cleaner WITH silicones, because silicone lubricates well and is safe on almost anything. It's expensive nowdays, but my previous can lasted probably 15 years.

author: alm
author_rank: Super Contributor
timestamp: February 04, 2024, 09:14:57 pm
content: Generally there are two types of contact cleaner: the gross, acid kind that is used to clean serious corrosion like contacts that are used outdoors or car battery terminals and needs to be fully washed off, and the milder kind that is used in more sensitive places like switches where it can't fully be washed out. You don't want to use the former kind anywhere near a scope.Quote from: David Hess on February 04, 2024, 01:32:49 amI second the recommendation to lubricate contacts after cleaning. Other well-known cleaners that contain PPE (polyphenyl ether) are the various Caig Deoxit products and Cramolin Contaclean. I believe there are special recommendations for cam switches that used the PCB as contacts, as often found in Tek scopes. Check the TekScopes groups.io archives.

author: David Hess
author_rank: Super Contributor
timestamp: February 05, 2024, 02:59:46 am
content: Quote from: Whitefoot on February 04, 2024, 08:51:23 pmSilicone oil works but has a very low surface tension to it tends to creep across every surface making it a contamination problem. The polyphenyl ether oil in MG Chemicals 801B is the opposite, and has a very low vapor pressure. It is more commonly used in vacuum systems.Either works great.Quote from: alm on February 04, 2024, 09:14:57 pmI could never figure out the Deoxit products. Caig goes to a lot of effort to hide details.QuoteThe Tektronix cam and finger switches are a special case which should never be lubricated. They can be cleaned with a slip of non-clay bearing paper wetted with a solvent and drawn through the contact while closed. Paper will clay in it will abrade the gold plating too much.

author: alm
author_rank: Super Contributor
timestamp: February 05, 2024, 01:38:24 pm
content: Quote from: David Hess on February 05, 2024, 02:59:46 amI agree. My understanding is G for (lightly contaminated) gold contacts or as finish on gold contacts after D. Use D for other contacts. The version with solvents (D5) if contamination can be flushed out and pure (D100) if it will stay in place or you want a more controlled application (obviously with solvent cleans better). Use S for contacts exposed to a lot of corrosion (e.g. outdoors, I never use it), and F for plastic or carbon pots. I commonly use D5 or D100 for general switches and G100 for sensitive switches in something like a Kelvin-Varley divider (don't want lubricant spraying everywhere, so G100 instead of G5).But I'm not making any claims of Caig Deoxit being better than other products with PPE. I believe Cramolin Contaclean is very similar to Deoxit D5.

author: Whitefoot
author_rank: Contributor
timestamp: February 06, 2024, 01:14:07 am
content: Quote from: David Hess on February 05, 2024, 02:59:46 amThat's a good point. It could be a problem in an industrial environment with stuff in the air contaminating things.I've used MG404B contact cleaner with silicone for years on my equipment, without any problems that I'm aware of, but in a clean, home environment. MG states that it leaves a thin film of DRY silicone.The MG Chemicals 801B does look like it might be a better choice for more demanding conditions.