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first question ever here:

I'm struggling with a 10K log potentiometer in an EQ. When at lowest CCW setting it's the same value as on full CW pos.

Is this typical when a pot goes bad or is that fixable?

update:

Thanks for the advice! I'll change the pot and maybe have a look at the wiper when I have it unsoldered.

update:

When measured 1 between the wiper and one of the end terminals the resistance varies gradually (log), but after it goes down to 0 at CCW position it sometimes jumps to the max. value:5.66K Which in this case is our Pultec EQ and results in full boost.3 We have a lot of people using our gear, so maybe someone just forced it and broke it.

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    \$\begingroup\$ This would be normal if you were measuring across the wrong two terminals (assuming you're reading 10K). You need to measure between the wiper and one of the end terminals. \$\endgroup\$
    – Scott Seidman
    Commented Jul 9, 2018 at 15:33
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    \$\begingroup\$ The resistance between the end terminals is constant, regardless of setting. The resistance between the wiper/moving contact/center terminal varies as you adjust the pot. \$\endgroup\$
    – Peter Bennett
    Commented Jul 9, 2018 at 15:44

2 Answers 2

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Share the part number or picture of your potentiometer.

enter image description here

If you measure resistance between A and B it will always be 10 kohm. Point C is called wiper end and you should be ideally using

A and C

or

B and C

terminals if you need to varying resistance.

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  • \$\begingroup\$ Your answer is correct for an open circuit pot. Results when measuring in circuit with pot still connected could be quite different. \$\endgroup\$
    – Michael Karas
    Commented Jul 9, 2018 at 17:00
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If you struggled with pot and only connect 2 pins failure would be open circuit.

There should be some minimum resistance like 1%, not Zero . If you forced it to try to get 0, but now get 10k, you broke it.

If you have tap pin, also connected to CW pin , that would explain the open circuit =10k .

Conclusion: Bust Pot. Unlikely repairable wiper but possible.

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