Scratchiness in Stacked Concentric Pots

[Runewalker]

I have two stacked concentric 500k Pots (4 pots in all) wired more or less like a conventional Les Paul - 2 vol, 2 tone, two humbuckers. The more or less part is that I have 3 minis, one for each pup selecting Series/Para/Single, and one on the bridge pup for in/out of phase.

When I roll a pot towards it's apex (10 on a Les Paul, or the highest volume, highest tone) at about 8 or 8.5 it gets an electronic scratchy sound from 8.5 to its apex. this is especially apparent in the volume pots

When tested on the multimeter, you can see the resistence drop 1-3k at that scratchy point. I think the output is also less when amplified.

What might cause this and how do I fix it?

[JohnH]

It can be some dust or something on the carbon track inside the pot that is spoiling the contact with the wiper at that point. You can get an aerosol switch cleaning spray that you squirt around the pot and it penetrates inside. Then you spin the knob a few times and it usually clears it. The spray is very volatile, so it evaporates, leaving a clean pot. If the pot is actually worn out though, then it may be time for a new pot.

cheers

John

[Runewalker]

Pot are nearly new, maybe 10-12 hours of playing on them.

should not have dust. It is not that kind of sound as I have some 53 year old pots and they have the type of prob you describe. i actualy know that symptom pretty weill.

This is electronic where a shorting type sound occurs, and the resistance visably drops. And movement before the 8-85 threshold is smooth and scratchiness free.
I wish it were a cleaning event. It is something else.

RW