TB-4 Wiring help

[stratto8418]

Hi everyone,
I have started building my bass guitar kit and am now up to the wiring.
I have downloaded the wiring diagram from the pitbull web site (3 pot).
I have a few questions and need a little help.
First of all. the pots i have in the kit are 1 x A500 (volume) and 2 x B500K (tone) and only 1 capacitor.
also the the wire for the pick ups is as follows.
red and white soldered together.
green with a shielding wire around it.
and black.
the wiring diagram for this guitar on this site states 2 volume and 1 tone.
Im confussed
please help.

thank you

[Simon Barden]

One capacitor is correct for the wiring diagram.

I agree that the kit should have two A500k for volume and one B500k pot for tone. It may be worth checking with a multimeter what the mid turn resistance is on the B pot between the middle tag and one of the end ones. If it is linear, then you should be reading around 250k, if log/audio, either nearer 90k or 410k (depending on the end tag chosen). If B is linear, then email Pit Bull and ask them to send out another A pot. If log, then the A and B designations on the kit pots are simply swapped (annoying but it could happen), so use the Bs for volume and the A for tone.

The pickups supplied have 4-conductor wiring, not the 1+ screen shown in the wiring diagram. Unless you feel like wiring the pickup coils in parallel rather than series for a brighter tone, or adding a coil split switch for single coil sounds, you use:
Black - signal hot
Green+screen - signal ground
Red+White - wires that connect the two pickup coils together internally. Leave unconnected and tape up the bare ends to avoid them shorting out. If you want a coil split, then this red/white combo is connected to an extra 2-way switch that can connect the wires to ground.

[Ivo Kalis]

One capacitor is correct for the wiring diagram.

I agree that the kit should have two A500k for volume and one B500k pot for tone. It may be worth checking with a multimeter what the mid turn resistance is on the B pot between the middle tag and one of the end ones. If it is linear, then you should be reading around 250k, if log/audio, either nearer 90k or 410k (depending on the end tag chosen). If B is linear, then email Pit Bull and ask them to send out another A pot. If log, then the A and B designations on the kit pots are simply swapped (annoying but it could happen), so use the Bs for volume and the A for tone.

The pickups supplied have 4-conductor wiring, not the 1+ screen shown in the wiring diagram. Unless you feel like wiring the pickup coils in parallel rather than series for a brighter tone, or adding a coil split switch for single coil sounds, you use:
Black - signal hot
Green+screen - signal ground
Red+White - wires that connect the two pickup coils together internally. Leave unconnected and tape up the bare ends to avoid them shorting out. If you want a coil split, then this red/white combo is connected to an extra 2-way switch that can connect the wires to ground.

So if I follow you correctly:
- use the black wire from the neck pickup instead as the blue in the diagram
-green+screen from neck pickup is signal ground on the first potentiometer
-use black wire from the bridge pickup instead of the red on the diagram
-green+screen from bridge pickup as signal ground for second potentiometer
-tape up red/white wires
-Use rest of diagram

But how to make ground with the bridge? there is no internal hole to get there?

[Trevor Davies]

So if I follow you correctly:
- use the black wire from the neck pickup instead as the blue in the diagram
-green+screen from neck pickup is signal ground on the first potentiometer
-use black wire from the bridge pickup instead of the red on the diagram
-green+screen from bridge pickup as signal ground for second potentiometer
-tape up red/white wires
-Use rest of diagram

But how to make ground with the bridge? there is no internal hole to get there?

Hi Ivo.

Yes, for the wiring. Just to be sure - each red/white wire is taped up separately.

For the ground to the bridge - My kit had a small hole drilled from the bridge post hole closest to the control cavity. In the cavity, this hole was very close to the jack socket hole. Hopefully your kit has this predrilled, but if not, it should not to too hard to drill.

[Ivo Kalis]

so this is what i thought you described to me. But somehow I only get Static noise from the moment I put in my jack plug.


What am I doing wrong?

[fender3x]

It looks right in the diagram:

I am assuming your wire colors are the same for both pickups...

For the neck pickup:
black should go to the center terminal, top pot
green and silver should be grounded to the pot housing.
white (shown as black in your diagram) and red should be soldered together. The exposed solder ends should be wrapped with shrink-wrap or electrician's tape to keep them from touching anything and creating a short.

For the bridge pickup...the same, except to the middle pot.

A ground wire should be soldered to all three pots and also to the ring lug of the jack.

A ground wire should come from the bridge to any grounded spot (any pot housing, or the ring lug on the jack).

Top and middle pot should have their left lugs connected. Left lug of the middle pot should connect to the middle lug of the bottom pot. Middle lug of the bottom pot should connect to the tip lug of the jack.

Right lug of the top and middle pots should be grounded to the case. Right lug of the bottom pot should connect to a cap, which should be grounded to the case.

Left lug of the bottom pot should not be connected to anything.


Judging by your diagram it looks like you might have cut the connection between the red and white wires. That would cause the problem you describe, even if all the other connections were good.

The PB diagram is for single coils like in a Jazz bass. The TB-4 uses humbuckers that should look like this:



Basically, the red and the green wire are from the "top" coil, and the white and black wires are from the "bottom" coil in the diagram above. If the connection between the red and white is cut, the bottom coil has no signal and the top coil has no ground...and you get hum/static.

If that's not the problem, you probably have a bad ground connection... You might want to send a pic of your wiring.

[Ivo Kalis]

I soldered the red and white together. but still just static. when I touch the snares it get's louder.

I think I'm taking everything apart to solder it again. Found out I placed one of the potentiometers wrong. switched A and 1 B for tone and volume. maybe this could cause my problem

[fender3x]

Changing pot location should would not keep you from having sound, but before connecting it, are you sure the pots are turned all the way up? It's probably a bad ground, but it's a good idea to check it with the pots all the way in both directions.

It may be just me, but I don't tend to re-use components. Pots and caps are cheap, and heat can damage them, so if you rebuild, you might consider using new pots and a new cap. I prefer to use all audio pots if you do that, although some people like linears in the tone position.

If you are not going to replace the components, I would start at the jack and work backward, re-doing all of the connections. Since neither pickup is working, chances are it is a ground or a hot connection relatively close to the jack.

If you do rebuild, you may want to test pickups and pots with a multimeter before putting them in.

[Trevor Davies]

Hi Ivo Kalis,

can you post a few pictures of your soldering, including the jack plug. That may make it easier to problem solve.