In general, direct current is harder on contacts than alternating current, because AC arcs tend to self-extinguish during zero-crossing. Arcing across contacts can cause corrosion and oxidation too. The copper and zinc oxides are nowhere near as conductive as either base metal, so electrical contacts made of brass can have problems if there’s too much oxidation on them.Įxposure to the atmosphere isn’t the only source of trouble for contacts. Other times, metal oxides cause problems. Sometimes this is handy, as when an aluminum screen door forms a layer of aluminum oxide that makes it essentially impervious to further corrosion. Pure metals rapidly combine with oxygen to form metal oxides, which usually have different properties than the base metal. Oxygen in the atmosphere is the culprit, and metals are the victims. It may not seem like it, but we live at the bottom of an ocean of corrosive gas. Oxidation is the Enemy Badly oxidized game cartridge connectors. With that in mind, I thought I’d look at contact cleaners that are in use today, what’s really going on when you clean contacts, and why contacts even need cleaning in the first place. All I know is that I’ve never found its equal for cleaning electronics gear. I never knew for sure if that stuff was Freon, but it was the mid-80s, shortly before CFCs were banned, so it might have been. He gave me some for my shop in a little jar. He had a 5-gallon pail of cleaning solution under his bench that he told me was Freon, which he swore by for head cleaning and general contact cleaning. I was working for a video production studio at the time, so there was a fair amount in common about our jobs. One of the regular chores we faced was cleaning the heads on tape machines. I visited him at work once, and despite the fact that he wouldn’t let me climb the 1,200′ antenna tower, I had a great time. Always read labels and dont use a brake cleaner that attacks plastics if there are any in the switch phenolic and ceramic are safe.I had a friend who was an engineer for a small TV station. On band and other open switches that are really filthy with greasy contanimants I'll use a store brand disc brake cleaner to clean down to bare metal and then D-100L to deoxidize. The only place I regularly use a spray is to get into pots, sealed control switches and the like and the CRC products as mentioned have been my choices for many decades. This is the one I use for initial cleaning on any metal including automotive connectors.įor long term protection after cleaning this is what I use.Įxpensive yes, but it will last for several years even in a high volume enviroment such as mine where there is always a backlog. In the Gold series silver is just one of the metals to protect after cleaning with the D series. Nowhere does it say anything about silver for the D series. It is designed to reduce silver salts to metallic silver, regardless of the specific composition of the salt. Yes, DeOxit can be used on non-silver contacts, but it's much more expensive than more appropriate choices. I make my own "Q tips" from a bit of cotton on a skewer or toothpick, much smaller than the commercial item, wastes less cleaner and gets into smaller spaces without snagging on rotary switch contacts. After a wipe with DeOxit the contact improved considerably, even though the surface didn't look any different.īack to the question, you can spray on a Q tip if you have a light finger on the trigger. Contact wasn't very good with light pressure. "Gramolin" became "Cramolin" which more recently became DeOxit when the US importer broke off from the German parent (it's still Cramolin there, or was several years ago).Īs an experiment once I took a piece of brass sheet and touched ohmmeter probes to it. I presume it was from "Gramme Ring" and "olein," the German for oleic acid. I once ran across a circa-1930 European trademark registration for "Gramolin," a treatment for DC motor commutators. Mmm, that silver cleaner sounds more like the L&R Dip I have a bottle of, with ingredients thiourea and sulfuric acid.
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