Precision Bass Wiring Diagram?

[WannaJazz]

I bought a pre assembled wiring harness for a Precision bass.

I wired it according to this diagram: https://www.gui****udeproducts.com/Images//Pbass_wir.jpg

The volume and tone knobs work backwards. The 'on' position turns the volume off. The tone pot works backwards also.

I know nothing of wiring. I followed the diagram, even though the rest of the harness ( the pots and jack) are wired differently.

The picture at the top is the pre-wired assembly.

As if I weren't confused already, I found this diagram which has the color of the wires from the pickup opposite of the first diagram.

Invalid Link Removed

Oh, I see. I can't copy either image into this thread.

Can someone please direct me to the correct diagram?

The pickups are from a MIM Precision.

Thanks!

 

[Gaebrial]

If the pots work backwards, I think that just means you soldered the wires on the opposite lugs.

The way a pot works is that the center lug is always "on" or "open". The knob on the top is attached to a sweeper on the inside that... basically, the knob determines how much the left and right lug are connected to the center one. So when it is halfway (on a linear taper pot, audio is different- that is something else though. You can ignore this parenthetical), the center lug is 50% connected to the right lug and 50% connected to the left lug. If it is turned 3/4 to the right, it is 75% connected to the right lug and 25% connected to the left lug. If it is all the way to the right, it is, in theory, 100% connected to the right lug and 0% connected to the left lug. You can extrapolate from there.

I hope that explanation helps with understanding what is happening with the pots. If you want to understand better, open up a spare/old pot by peeling back the tabs and take a look at the inside. It is a pretty simple concept if you can visualize it.

So, if my quick thinking is correct, if your knobs are wired backwards that means what you soldered on the right lug should have gone on the left, and visa versa.

Also, it is better to think of wiring as controlling the "flow" of electricity, because the color of the wires, obviously, doesn't mean anything. You want to trace the "positive"*** flow of electrons and make sure that they go through the different components the way you want them to. Anything that touches anything that is connected to the ground will be grounded out, aka silent. So if you use that thinking, go through and make sure that when you turn your knob that it connects you positive*** flow in varying percentages to what is going to ground, whether that is a wire to the back of the pot on the other lug, a wire going to the negative lug on the jack, or a capacitor that is bleeding the treble frequencies to ground.

***There really isn't a "positive" or "negative" flow in a guitar from what I understand because it is an alternating current, so it is switching between the two rather rapidly. What is more, back when they were laying down the terms and stuff for electrical engineering they labeled the flow of electrons as being positive, but since electrons are negative it is really a negative flow. From what I understand, they left it like that because it had been in use for so long beforehand, and it really doesn't affect the formulae or anything on the theoretical side. This info isn't useful or necessary for guitars, but I don't like giving out half truths that could complicate things down the road if you try to do more complex stuff.

 

[line6man]

You are missing a ground wire.

 

[sissy kathy]

You are missing a ground wire.

... between the two pots.

 

[WannaJazz]

Thanks for the replies!!

I didn't wire the pots and jack together.

I bought the harness pre-assembled.

Just to be clear, I need to ask, besides needing a ground wire between the pots.

I also need to rewire the pots?

 

[Gaebrial]

Thanks for the replies!!

I didn't wire the pots and jack together.

I bought the harness pre-assembled.

Just to be clear, I need to ask, besides needing a ground wire between the pots.

I also need to rewire the pots?

Well, you can learn to love backwards pots. Maybe they will help if you have dyslexia.

Out of curiosity, do you have a lot of hum/grounding issues when you hook it up?

 

[Crater]

That wiring harness you purchased assumed your pickguard would have foil shielding on the inside to act as the ground conductor. Your picture shows that your pickguard is not shielded...

Should look like this: (thanks to guitarmechanic.com for the hotlink)

In this case, they have run a separate ground wire, which is always good practice, but if the pot cases are grounded you can get away with using the foil shield for the ground.

 

[WannaJazz]

The diagram seems to match the way the pots are wired.

I can change them if I can find out which wire goes where.

And I will add a ground wire between the pots.

If somebody can see where the wires are crossed, I would appreciate that information.

 

[line6man]

That wiring harness you purchased assumed your pickguard would have foil shielding on the inside to act as the ground conductor. Your picture shows that your pickguard is not shielded...

Should look like this: (thanks to guitarmechanic.com for the hotlink)

In this case, they have run a separate ground wire, which is always good practice, but if the pot cases are grounded you can get away with using the foil shield for the ground.

While shielding is a good thing to have, it should NOT serve to make the ground connections between the pots. It is common for mass production instruments to do that, but only because it cuts costs. If you are doing your own wiring job, then you will want to make sure that it gets done the proper way. You want dedicated soldered ground connections, because they are more reliable than mechanical connections, especially if the pots or the jack get loose and lose their contact with the shielding.

 

[verstft]

I'm a beginner but here is my opinion. TBers, please correct me if I'm wrong.

Based on your photo, it looks like you don't have foil or copper under your pickguard so you wouldn't be getting ground from that? I would groundthose two pots first by adding a black wire between them. Then move your way down the list.
If you don't have wire. Just use the core of an old string to bridge them...

Also, just be really conscious of wires overlapping or pinching in a weird way when you install the pickguard which could cause all times of wiring problem. Finally, you don't need that extra lug on the tone pot. I'm not sure what the consensus is but I like to chop it to avoid shorts or potential things getting in contact with it.

Here's a photo:

 

[line6man]

Based on your photo, it looks like you don't have foil or copper under your pickguard so you wouldn't be getting ground from that?

Again, the purpose of shielding is to shield, NOT to ground. There should be dedicated ground wires (one is missing) in addition to shielding.

 

[sissy kathy]

The diagram seems to match the way the pots are wired.

I can change them if I can find out which wire goes where.

And I will add a ground wire between the pots.

If somebody can see where the wires are crossed, I would appreciate that information.

Get that ground in first; there's a possibility that things are working wrong BECAUSE of the missing ground. Remember a tab on the the volume pot is part of the ground and I suspect it is back feeding things on you.

 

[WannaJazz]

Okay, I got it!

I overlooked the way the cap was soldered to the middle tone lug. So I switched it with the white wire from the volume pot.

I also added the ground wire between the pots.

And it works as it should.

I do have shielding tape on order.

I thank everyone who helped me fix this!!

Have a good day!!

 

[verstft]

Glad you got it sorted it out. It can be a bit frustrating when you're looking at a wiring diagram over and over and can't quite get it right.

So I switched it with the white wire from the volume pot.

That really shouldn't have had any effect but does anybody know if there is a difference? I've also seen people go from the center lug on the tone cap bridged back to ground on the folded leg of the volume pot. Anybody know?

 

[line6man]

That really shouldn't have had any effect but does anybody know if there is a difference? I've also seen people go from the center lug on the tone cap bridged back to ground on the folded leg of the volume pot. Anybody know?

Never solder a capacitor between two pots. If a pot gets loose, you risk damaging the capacitor, because the capacitor is put under strain when the pot twists around in the control cavity.