Cleaning Electrical Contacts
The copper parts of the connections, like circuit board edge connectors and the like, can usually be cleaned with a white eraser. If you want to get aggressive, try a fine Scotch-Brite pad, but be sure to leave some copper foil on the connector edge. For most jobs the eraser is the safest way.
The brass and silver and tinned connector pins are self-cleaning when they are removed and replaced. A thin layer of oxide forms on the surface, protecting the base metal from further damage. The pins and such are designed so that the oxide layer is scraped off when they are assembled/disassembled, exposing virgin metal for the best current flow.
All that said, I learned a good lesson from a marine electrician-- use silicone dielectric grease on the connectors to protect them from corrosive elements. In the boat this is usually salt water, but in the car this can be something like fumes from the battery, or from something that's in the air that day. No problems here in the crystal-clear L.A. basin, but some places may have real smog. Add a little moisture, shake well... Anyway, this stuff is sold in small quantities as "spark plug boot grease" at auto parts stores, or in larger tubes at industrial hardware stores as "high-voltage bushing flashover grease" or something similar. I buy Dow #5 in a small tube that lasts a long time. A little in the connector before assembly means you will never have a corrosion problem there again. Great stuff!
Also good to know-- NEVER use conventional RTV products on or around electrical connections. Use only non-contaminating non-corrosive stuff made specifically for electrical applications. Conventional RTV uses acetic acid as part of the curing agent, and plays hell with any nearby electrical connections.
And last but not least, most common spray contact cleaners are a waste of time. The ones that work for degreasing and really cleaning tend not to be sold at radio shack stores, and also like to eat some common plastics. Use your best judgement on this.
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