Confusing problem with simple (?) pickup install? PROBLEM SOLVED!

[Pill Bass]

Hey everyone,

I'm hoping somebody out there with more experience than I can help me with a pickup issue that has be baffled. My plan was to drop a pair of passive Bartolini Jazz single-coils (model 9S) into a guitar that had active EMGs in it in an effort to thicken up the sound a little. My first attempt used Bartolini's own wiring diagram:

which turned out to be completely wrong and led to absolutely zero output from the guitar.

So I did a little research into how other folks advise one to wire up a V/V/T Jazz bass (Fender, StewMac and others, including looking at my old setup with the EMGs), and came up with this:

This wiring proved a little more successful, but not completely so. Here are the symptoms I'm seeing:

Neck volume wide open, bridge volume off:
no output, sweeping tone control had no effect on lack of output.

Neck volume off, bridge volume wide open:
good output, sweeping the tone control had the expected effect, except backwards (with the knob "rolled off" the tone was brighter; rolling the knob "full open" reduced the highs - I'm guessing I put the capacitor on the wrong pot leg, but I can live with it for now).

But here's where it gets weird: with the bridge volume wide open, bringing the neck volume up REDUCED the output until, with the neck full on, there was no output at all. I know with passive Jazz basses, the controls interact, but I'm not sure exactly how they are interacting to give me the troubles I'm seeing.

Do I have a bad pot in the neck volume position? A bad pickup? Is the schematic wrong?Any advice on what to look for when troubleshooting would be gratefully appreciated.

Thanks in advance,
BD

 

[Killed_by_Death]

You can't use the original pots, the ones that were there for the active EMGs.
If you'd like to get the most brightness out of it, use 500K Ohm pots.
I'd recommend linear taper for volume & audio taper for the treble cut (tones) pot.

Here is a good drawing to use:

https://www.seymourduncan.com/wp-content/uploads/2016/05/JazzBass_Standard.pdf

The treble cut pot in your second diagram is incorrect, which is why you're hearing it operate backwards.

 

[Pill Bass]

You can't use the original pots, the ones that were there for the active EMGs.
If you'd like to get the most brightness out of it, use 500K Ohm pots.
I'd recommend linear taper for volume & audio taper for the treble cut (tones) pot.

Here is a good drawing to use:

https://www.seymourduncan.com/wp-content/uploads/2016/05/JazzBass_Standard.pdf

The treble cut pot in your second diagram is incorrect, which is why you're hearing it operate backwards.

K_b_D,

I did purchase brand new pots for this install; I'm not trying to re-use the ones from the EMG setup. The Seymour Duncan drawing was one of the ones I used as a source when I created the one I posted. SD didn't specify any values for the pots in their schematic, but I think you'll find theirs and mine electrically equivalent, except for the treble cut pot. I just need to move the capacitor over to the other leg.

As for the 500K pots, the reason for putting the Barts in in the first place was the guitar was too bright. That's why I went with 250K.

BD

 

[Pill Bass]

All,

Turns out the problem wasn't with my soldering or wiring-diagram-following skills. When I put the neck pickup into its pocket, the braid on the coax lead ended up touching the coil tap pin for the center conductor. The pickup was shorting itself out via the cable. I added a couple of layers of electrician's tape over the offending coil tap and everything works like it should now.

For you luthiers and repair people out there - here's another troubleshooting tip to keep in your hip pocket.

BD

 

[Killed_by_Death]

Ha, I just came back to say check for shorted spots...

Shrink tubing works better.