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quick question. I have two 10 turn precision potentiometers and I tested both when I bought them a few weeks ago, both worked as expected. However now that I have epoxied one of them into my project and wired it up, I don't get any resistance. I get a max reading all the time regardless of where the dial is set. So then I pull off the wiring and do the same setup with the other potentiometer and I am still getting expected results.

What could be the reasoning for the sudden difference in readings? Could the first one have gone bad, and if so how often does this happen and how can I avoid it in the future?

Everything falls within recommended specs of the pot and neither has been really used at all.

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    Could the epoxy have entered the pot? – Gerben Jul 3 '16 at 9:12
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Multi turn pots range in size from about sugar cube dimensions:

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...to weighing a pound or more:

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It would be easy to imagine epoxy entering a small plastic multi turn pot and "freezing" the parts within. If this is what happened, try using a faster curing glue or mount the pot on a Printed Circuit Board (PCB) and glue the PCB.

  • I suppose it is possible, I will have to remove it and try the working one and see if I cant be more careful in the mounting process. It is fairly solid and I doubt any epoxy got in it but you never know. – Chris James Champeau Jul 3 '16 at 20:39
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Trimmers have a really low current rating, so if you hadn't protect it enough, maybe you have broken it. Always remember a pull up resistor of 10k or more.

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