Quote:
Originally Posted by miniman82
vertical height pot? They are prone to tin whiskers
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Funny you should mention that. This week I was working on a 1930s Stewart Warner radio that had a serious case of dendrites inside a potentiometer:
"Dendrites" are the fuzzy, bristly stuff growing down from above, in that view. (At least in NASA terminology. They use the term "whisker" for a slightly different phenomenon, the growth of a long, single metal hair rather than a bunch of fuzz.)
First time around, I opened up the pot case and gave it the usual DeOxit treatment without looking very closely. When problems persisted, I reopened it and discovered all that cute metal fuzz making intermittent shorts inside.
Dendrites clean off easily, but you can't count on simple spraying to get rid of them. They (or whiskers) can also form on the outside of a control, making a short from the control case or terminals to chassis or some other components.
Yet another reason to
clean, clean, clean these old chassis, especially if they have been in a moist environment.
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html