Active Bass Stops Working when bass knob turned up

[Teegan Heiniger]

I have a Charvel Pro Mod San Dimas JJ bass. In active mode, everything works right when the bass control knob is anywhere from 0-4.9. Once it hits the little indent of the half way mark, my bass doesn’t output any signal. I am wondering if anyone has any experience with this or know how to troubleshoot. I do have a multimeter. I’m thinking it is either the pot or possibly the preamp.

 

[kgbeast]

Probably one of the contacts touching the foil.

 

[Teegan Heiniger]

I took the bass pot off and the same issue kept going. Not sure if somehow another one is causing it

 

[Crater]

I do have a multimeter.

I took the bass pot off and the same issue kept going.

Now that you've removed the pot you can test it with your multimeter. From the symptoms you describe, it sounds like the bass pot's track is worn out and becomes an 'open circuit' when it's turned above center. The preamp signal passes through the bass pot, that's why it won't work without it in the circuit.

 

[Teegan Heiniger]

Now that you've removed the pot you can test it with your multimeter. From the symptoms you describe, it sounds like the bass pot's track is worn out and becomes an 'open circuit' when it's turned above center. The preamp signal passes through the bass pot, that's why it won't work without it in the circuit.

If that’s the case, does it just need replaced. No way to fix?

 

[Crater]

If that’s the case, does it just need replaced. No way to fix?

Yes, just replace it with the identical part. Typically active preamps use 50 k Ohm linear pots for their tone control but it's best to look on the pot itself, they are usually marked, or measure resistance across the outside terminals. You'll need to match the length of the threaded portion of the pot's shaft too.