How can i verbs the contacts of electrical devices?
Answers:
if not working try a sandpaper
rubbing alcohol and a qtip There are several contact cleaners on the market and most are "plastic proof" and can be used slightly liberally. You can find them at places such as Radio Shack, Best buy, Wall Mart etc. Isopropol alcohol (rubbing alcohol) is also moderately good surrounded by most cases. The use of a "Q" tip depends on what you are cleaning. Those little chamois tipped plastic ones for use to clean video heads are better on circuit boards etc. as they don't shred and give notice "hairs" behind close to Q tips do.
The contacts on the edge of circuit cards can be cleaned beside a simple pencil eraser.