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Testing a Potentiometer

gmohrs

New member
Joined
Oct 1, 2019
Messages
11
Hey techs. Is it possible to test a potentiometer with a voltage meter? I’ve been trying to split a stacked P-90, and I’m stymied. Everywhere I look on the internet, it seems like everyone has a unique wiring pattern. I read that the push/pull pots are kinda fragile, and can be ruined by to much heat from the soldering iron. Now I’m not sure if my wiring is the problem, or if I have fried the pot with all my trial-and error attempts at this. Thanks.
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
673
With a voltage meter - no, it will read zero volts whatever part of the pot or switch you connect it to. With a multimeter that can measure resistance and continuity - yes. What do you want to test, the pot or the switch? they are two separate things.
 

PaulD

Active member
Joined
Jun 25, 2007
Messages
673
A few simple checks on the pot would be to first measure the resistance between the two outer lugs, this should read something close to the pot's rated value (typically 400K - 600K for a 500K pot would be considered OK). Next connect the meter to the centre lug and one of the outer lugs, with the pot turned fully in one direction it should read close to zero ohms (anything less than 20 - 30 ohms is OK), with the pot turned fully the other way it should read close to the pot's rated value again. Now set the pot to the half way point, if it is a linear pot it should measure approximately half the pot's rated value, if it is a log pot it should read either approximately 10% or 90% of the pots rated value. Repeat these checks with the meter connected to the centre lug and the other outer lug and these values should be reversed.

All of the above measurements must be done with the pot disconnected from the guitar otherwise you will not get meaningful readings.
 
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