JS-II bass pickup question

[Happy Face]

Hi all. A few years ago I bought a beat up JS-II with the Guild humbuckers. I had it refinished when the luthier installed Darkstars in it. Since then it's been one of the two basses i use when we play out.

Last night, thanks to a flourescent light, I noticed something i should have noticed long before:

When I play with the neck pickup alone, there is no hum. When I add the bridge pickup or play it alone, i get hum. especially if the treble pot on the bridge pup is above 5.

To my very limited knowledge that makes no sense. Do you think the pickups are wired improperly??

Thanks!

 

[fronobulax]

Mine doesn't do that with factory wiring and PU.

Does this help?

 

[Happy Face]

Thanks once again, Frono. I'll have to open the baby up and take a look.

BTW - I found a printout sitting in the case from the Guild group on the old D-Pit. Someone was talking about removing a resistor on a white wire which he said cuts the volume on the bridge pickup. Did you ever hear of this?

Thanks.

 

[fronobulax]

Thanks once again, Frono. I'll have to open the baby up and take a look.

BTW - I found a printout sitting in the case from the Guild group on the old D-Pit. Someone was talking about removing a resistor on a white wire which he said cuts the volume on the bridge pickup. Did you ever hear of this?

Thanks.

Not ringing any bells with me although I have never been one for modifying something that works "good enough". In my case the solution to my JS "problem" was to remember that the Starfire was my first love.

However, the schematic above and the picture below do show a resistor "on" the bridge PU whose function may be level control. I'm just not enough of an EE to know for sure that level control is the function. I think in my bass, there is some gray wrap on the white wire, presuming, of course that I am mentally reversing the controls correctly. Hopefully the lower right (as pictured) pot has the resistor you're talking about. Also note that all of the grounds are tied together, in some cases with a bare wire. Perhaps the absence of something similar lies at the root of your problem.

 

[Happy Face]

Awesome!! I'll print both of those and use them to compare.

The ground wire idea is promising.

Thanks again. I really appreciate those images and your thoughts.



Starfire... yes, i know...

 

[danerectal]

What value is the resistor? Bad Beer Rots Our Young Guts, But Vodka Goes Well. Get Some.

 

[fronobulax]

What value is the resistor? Bad Beer Rots Our Young Guts, But Vodka Goes Well. Get Some.

Well 20+ years ago someone thought it was 150 K ohms.

brown, green, yellow, empty, gray.

Empty may have a tan in it, almost same color as body. I'm looking at a blow up of the pic because that's easier than getting the bass out of the case and finding a screwdriver.

 

[danerectal]

That sounds like quite a load, if that's accurate.

 

[Happy Face]

Frono-

The innards of my (newer) JS-II look quite different. One reason is that the suck switch was taken out. But the components are all different.

I could not find the resistor in the cavity. Either it is up near the pickup or a previous owner sliced it out.

 

[fronobulax]

Maybe when they put the DarkStars in the changed or upgraded a few other things as well.

I did confirm that the resistor we were talking about was going to cut volume. What I negelected to do was note the rating of the pots because the resistance of the pots would give some clue as to how the pickups were supposed to compare.

Back to your bass, if can you figure out enough to know if everything is grounded properly? If you post pics I'm sure several people will try and decipher out how things are wired.

 

[Happy Face]

Thanks Fronobulax. It is so different that it might be an interesting comparison. I'll fire up my camera.