Scratchy pots on Precision Bass

[EBE]

Our bass player has an old precision bass that has some scratchy pots. I took the bass and put in some used pots from my parts bin that seemed to work when I put them in. Next time we play, the pots are scratchy again. Very odd.... So I take the bass home and put in brand new 500Ka alpha pots. Everything is fine, the bass is quiet and sounds good. Next week, the pots are scratchy again. BOTH pots. Now I am ticked.... Could this problem be related to something other than the pots? Has anyone had a similiar problem before?

Norm

[Plexi]

When you try the guitar at home and its ok.. are you useing the same amp that you use to play through the week later. Sounds more like an amp problem. I'd try the guitar through a few different amps. If its a tube amp your playing through try changing the channels tube your useing. Thats the easiest try for first. You may have to see or test to see if its the guitar thats the problem,or its when its in the amp. Also could be the cable.
Richie

[EBE]

The scratchy problem has always been on his amp/his cable. I will give it a try on a different cable ran to the PA.

Norm

[Nederamp]

The cause of scratchy pots could be caused by a leaking Coupling capacitor just before the volume potmeter. In that case there would be a small dc voltage added to the Signals'AC voltage. This would be the reason for the scratching.

If the pot on the bass is scratching then maybe there is a small DC voltage leaking back from the input Jack to the guitar. This would mean a defect first pre-amp tube. You could try to measure for DC voltage by putting the jack in the amp and then measure if there is a small (millivolts) voltageon the jack that goes to the guitar, then it is certainly the amplifier.