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Paul[_13_] Paul[_13_] is offline
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Default Bourns Pot Shafts Not Long Enough!

On 10/13/2018 5:17 PM, Scott Dorsey wrote:
In article , Paul wrote:
No, you are misunderstand the situation.

With the wiper and shaft taken off, there are two traces on the
pot: one trace for the variable resistance, and one trace for the
center pin. The trace for the center pin is NOT connected to pin 2.


Right. There is a contact connected to the center pin which touches that
trace. But the contact is bad, or that trace is dirty.

Sometimes instead of having that second trace, there is a contact that
connects to the side of the rotating shaft in order to provide the
connection to the sliding element.

Remember: the sliding element moves, the pin is static. Therefore there
is a moving contact between the two. Moving contacts go bad.

There is an open there, and it's somewhere embedded inside
the plastic moulding. There's nothing I can do with it, without
destroying it.


There's an open there. Flood it with cramolin. Get cramolin behind the
plastic molding. Everything that moves, get cramolin on it. Just pump it
full until it comes squirting out. You can usually do this without taking
the pot apart.

What you are describing is one of the more common pot failure modes.


No, there's nothing more can do at this point, which is why I
ordered new pots.

Look at this pic:


https://encrypted-tbn0.gstatic.com/i...NGiz_quRoJu2nQ

See the center ring? That's supposed to be connected
to the center pin. In my case, it's an open, and unlike
this picture, the trace disappears into the plastic moulding.

The ring itself is clean, and has good continuity, but there is an
open EMBEDDED INSIDE THE PLASTIC. I could try to break the plastic
apart, but then the whole thing will be toast!

I think my chances are decent, to replace a new shaft with the old
one.