RC Battery Charger Repair

A co-worker came to me with this battery charger for charging his R/C plane's batteries. It shorted out at some point and stopped working, so I cracked it open to take a look inside. It wasn't terribly expensive, but with shipping it would cost around $100, not to mention ahving to wait around for it to arrive.

First step is obviousl to figure out just what wen't wrong, so you need to open the case up. It is pretty easy, just four screws on each side and it opens like a clamshell.

Immediately when Iopened it, I noticed a trace that was completely god in the middle. I followed the trace back, and found another break in it, and unpon re-examination of the first trace, I saw yet a third trace burnt out.

I figure that when the battery that was being charged shorted out, it pulled too much current. This board (and charger) is fairly cheap, the wholething seems to be coated with enamel, so I doubtit had over current protection for this sort of situation. I figure the surge of current broke the traces.

Now, how do I fix it? I didn't have any conductive glue, no magnet wire on hand, and no transformers tos alvage it from, but luckily I had some scrap ethernet wire on hand. Stripping that gave me plenty of solid copper wire to work with, perfect for repairing the traces.

Now on to repairing. I plugged in my soldering iron, and when it was warmed up, I tinned each side of the trace, soldered the first part of the wire, when it was cooled moved onto the next side, then trimmed off the excess wire.

When I was taking the circuit board out, the thermal pads on the voltage regulators came off, so I replaced them with some high quality thermal paste.

Now all that is left is to put it back together and test it out.

Now you have a working battery charger, no wait, no cost, just a little bit of time.