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Potentiometers for guitars
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Why would the ohm reading be lower after soldering a potentiometer for guitars. E.g: before soldering 522K and after soldering 505K. Has the pot been fried or is this normal?
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If components are wired in, their resistance will reduce the reading. If there are no connections made, heating of the carbon strip inside typically reduces the resistance temporarily. For a pot the change you are observing is not unusual or cause for alarm. Measuring the resistance from the tap (middle) terminal to either outside terminal should show a steady change as you slowly turn the control shaft.
A non-linear taper will produce a sudden change near the extremes and will have a different resistance form one side to the other when the shaft is turned to mid point (halfway).
A non-linear taper will produce a sudden change near the extremes and will have a different resistance form one side to the other when the shaft is turned to mid point (halfway).
I mean all components not wired in, just with ground lug soldered to top of pot and pot full on, just that initial heating As new reads e.g 520k then after initial sodering - just the ground lug link - when cooled off reads 505k, goes up to abt 510 a day later. I guess basically heatng affects the resistance of the track, and may recover a bit (or even fully in time). I suppose somewhere you have to draw the line between temperature changing it a bit to excess soldering wrecking it.
The test I described is a good preliminary check for the condition of a pot. If the resistance increased significantly or you obtained inconsistent readings, that would be a more likely cause for concern. Ultimately installing it in the circuit and checking its actual performance (dropouts, scratchiness, etc.) is the best indicator of acceptable function. Its not altogether impossible that heating it improved its performance although a lubricating control cleaner spray is typically the only practical potential cure for an aging pot. Excessive unnecessary heat should always be avoided.
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