Back in September 2016, I
appealed for information about chargers for prismatic or 'gumstick' NiMH batteries, as used in several models of 1980s Sony mini-disc Walkman. Andy a.k.a.'Scimitar' kindly offered me a second-hand example, designed to charge two prismatic or AA cells simultaneously, at a very reasonable price and I have just got round to fixing it.
On arrival, the charger was working but had clearly suffered from corrosion due to leakage from an AA cell. I dismantled the charger and found that one of the AA negative spring contacts had disintegrated, and that the corrosion had penetrated right through to the copper foil side of the PCB. In removing the remnants of the old spring contact, part of the copper foil was found to be corroded away.
I fashioned a replacement spring contact out of a bright nickel-plated paper clip of roughly the right gauge, copying the profile of the remaining undamaged contact, and reinforced the damaged copper land on the foil side of the PCB with tinned copper wire. With a bit of fiddling, the new contact was fitted and secured to the board with a generous quantity of solder. The rest of the job involved removing all traces of corrosion from the remaining contacts and from inside the plastic case. On reassembly, the new contact required minor adjustment and the charger then worked perfectly. The new contact is the one on the upper right in the first image.
Thanks to Andy for the charger.
Phil