[sdiy] Tin Whiskers

[Glen]

I knew a lady from Florida who had repeated problems with her Hammond organ
developing a silvery frost-like surface on many of the metal chassis
surfaces. It would cause her pedalboard switches to leak enough current to
permanently switch on pedal notes. The problem was made worse by the fact
that the circuitry connected to the switches had a very high input
impedance. Any leakage at all seemed to be enough to fool the organ into
thinking that a pedal was actually depressed. It didn't need a dead
short--just a little leakage, and it was totally useless.

She had the problem repaired multiple times in Florida, and it kept coming
back. She moved to nearby Kentucky, and I got the chance to tackle it. I
eventually took out the pedal chassis and stripped all the parts from it. I
sanded off the frosty surface and had my brother paint it with professional
non-metallic autobody paint. (He paints cars for a living.) After painting
the chassis, I reassembled the chassis with all the parts and reinstalled
it into the organ. As far as I know, the organ never needed treatment for
whiskers again. (That was probably 15 years ago.)

That worked with a plated steel chassis, but it's a little harder to apply
the principle to IC pins or relay contacts. It's someone else's turn to
suggest a solution for those.   :)


take care,
Glen

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