Tin Whiskers

[Tom9589]

How do tin whiskers manifest themselves in a pot? Do they become less noticeable as the equipment warms up? Are they more prevalent in carbon pots or wire wound pots? Any way to remove them?

[Electronic M]

They usually grow from the metal on the terminals and or the casing.
Usually if they are growing on fixed parts they'll make a fixed short that will stay. If they grow on or in the path of a moving part like the wiper they'll make and or break contact as you adjust the pot.

An easy first round clean is to hit the exposed terminals with a toothbrush and possibly something to dissolve them.
If that don't work you can dismantle the pot and lightly sand and polish the metal surfaces.

[Yamamaya42]

Originally Posted by Tom9589

How do tin whiskers manifest themselves in a pot? Do they become less noticeable as the equipment warms up? Are they more prevalent in carbon pots or wire wound pots? Any way to remove them?

WHY, is unknown
https://en.wikipedia.org/wiki/Whisker_(metallurgy)

once you get them they don't go away.

you got to scrape and clean them out, and try to paint and/or polish the metal to try and stop it from coming back

[dtvmcdonald]

Originally Posted by Yamamaya42

WHY, is unknown
https://en.wikipedia.org/wiki/Whisker_(metallurgy)

once you get them they don't go away.

you got to scrape and clean them out, and try to paint and/or polish the metal to try and stop it from coming back

Silver whiskers and tendrals (like grapvine) can grow grow to many inches long and many millimeters in diameter. This is slow at room temperature but speeds up at a couple of hundred degrees C and the presence of sulfur.
Natural occurrences can generate specimens a foot high that sell for over $100,000. So can fakes. (OOPS!) The natural ones an grow is less than "geological time" and the fakes in months.

[Phil Nelson]

For the curious, here are dendrites found in the volume control of my Stewart Warner 1865 radio:



Before cleaning, that pot made spectacular crashing noises!

Regards,

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html

[kvflyer]

I had a problem with an Admiral 26R12 that had a vertical linearity problem. Rotating the control didn't change the voltage (a clue that I missed!!!!!). Eventually, there was a pop and collapsed vertical sweep. Eventually, I found the problem to be simply tin whiskers on the control. A good scrubbing with the toothbrush was the quick, and inexpensive fix. Now, I am on the lookout for that issue.

[Yamamaya42]

Tin whiskers MAY have been the cause of the burn out in the v-height pot on my stromberg carlson x-21 .
https://i.imgur.com/SrGOwaf.jpeg

no way to know for sure, cause it had 500+ boost on there and it carbonized, gotta love that smell! :P