My first build diary JBA4 Jetblack

[Simon Barden]

Sounds like a missing ground link somewhere. I’m not a fan of mini-pots unless there is no alternative space-wise, but even the kit pots work.

If you are working to the kit wiring diagram:

https://www.pitbullguitars.com/wp-co...B-4_2014v2.pdf

…then there are things to note.

1. The bent-back tabs on the volume pots aren’t shown soldered to the back of the pots.

2. The bridge ground wire and tone pot cap aren’t shown soldered to the back of the tone pot

3. The factory wiring isn’t shown so I’m not sure if they rely on the control plate to provide a ground path between all or some of the pots. You’ve obviously got an output, but I don’t like relying on the control plate to do this (with some specific exceptions) and with the non-conductive black paint finish on yours, it’s simply not a reliable method.

The wiring diagram on this web page shows a complete version of the Pit Bull diagram. Use it in preference to the Pit Bull one.

https://guitarelectronics.com/jazz-b...agram/#gallery

If in doubt, post some pictures of the wiring. You may need a few, as we’ll need to see all the pot connection and where they run to, and it’s hard to do that with just one photo as the wires normally cover up a lot of the soldering details and it’s important to be sure if any solder joints look bad.

[Jetblack]

Yeah I will pull it apart again and sus it out. I ran a thicker ground wire from the bridge to the back of the tone pot as per the diagram also the diagram came with the new pickups, both showing the same thing. The bridge and neck ground wires are soldered to the perspective pots, and the positive wires are soldered to the perspective pot tabs, as indicated by the diagrams. There a possability the bridge ground wire has been compromised, as ive installed a chrome bridge cover and the hole I drilled for the insert hit the ground wire recess, hence a new thicker ground wire, it may not have cleared from the insert. Looking at both those diagrams, one shows the bridge ground wring to the tone pot the other one shows the bridge ground wire to the volume ?? Is there any difference ?? I also sanded the back of the bridge to clear an area from the paint to give it good connection, also used copper tape and laid out the ground wire to sit over it and made sure it rested against the back of the bridge.

[Simon Barden]

Provided the back of the pots are all grounded, it does’t really matter which pot a ground wire goes to.

There is a theoretical benefit in wiring all the grounds to a single point (‘star’ ground wiring) in minimising any noise pickup, but for practical reasons it’s easier to take the pickup ground wires to their respective pots (especially when they use braided or shielded output wires). But in reality any slight increase in noise from using more of a ‘tree’ ground wiring pattern is normally well below any noise from the single coil pickups and amp circuitry.

You want to avoid creating a ‘ring’ of ground wiring if possible, but if you’re using a metal control plate or cavity shielding (or both) that can be very hard. And I find that shielding the cavities gives far more benefit in noise reduction than the introduction of multiple ground paths might add to any increase in noise, especially if the primary ground connections are short and of very low resistance.

[Trevor Davies]

Looking at both those diagrams, one shows the bridge ground wring to the tone pot the other one shows the bridge ground wire to the volume ?? Is there any difference ??

No that should not make a difference. Just need to ensure ground wires linked all of the pots like in the guitarelectronics picture.

EDIT: 1 minute too late!

[Jetblack]

Here is some pictures, Let me know if there are any others you may need.

[Jetblack]

This is how I set up the bridge ground. Unfortunately while drilling the holes for the bridge cover. I hit the ground wire to the bridge. The new wire may also be corrupted, I have pretty good idea this is what has happened. So its either try and drill a fresh bridge/ground hole at that angle or track the ground wire up via the bridge pickup cavity. I was sure I was going to miss that wire when I drill into the body, but no, smack in the middle of it, completely destroying it. New wire but still having problems.

[Jetblack]

Yes thats how I did in accordance to the diagrams, but there is a sneaking problem and it may still be the bridge grounding. I drilled into the ground wire accidentally, I have replaced the ground wire but the inserts I used for the bridge cover may have torn into it as well, so I may have to relocate the bridge ground wire.

[Simon Barden]

The bridge grounding is for noise reduction. It doesn't play a role in the volume or tone pot operation.

Have you got a multimeter? if not you really should get one. Even the cheapest will do for guitar electronics. You'll want to check the ground continuity and resistance levels.

The pots all seem to be wired correctly, so it comes down to checking whether the solder connections are good or not. And you really need a multimeter for that.

[Simon Barden]

In addition, the copper shielding needs to be grounded for it to work. With this sort of bass, you'd normally expect the chrome control plate to be connected to ground, and for the plate to touch the copper, creating a ground path.

With the black plate, the paint is insulating, so this isn't happening.

I'd take the pots and jack off the control plate, put copper tape all over the underside of the control plate, and then put the pots and jack back on. I'd also add some extra tabs of copper out from the cavity shielding to where the three control plate screw holes are. This means you know that the screw pressure is holding the plate to the copper at those points. It's amazing how a bit of pressure can make a much better connection here.

[Jetblack]

Yes I have multimeter, just havent got around to checking resistances, that will be my next mission tomorrow. I havent really completed the shielding at this point its only partly done I may have jumped ahead with my complaint of crap pots, was somewhat frustrated at forstly drilling into the ground wire then putting it all back together without realising it.Thanks Simon.