Ground Wire On Tune-O-Matic Bridge

[ericmeyer4]

I am rewiring a Gibson Explorer and I had a bad hum going on. After not being able to trace it down I decided to start from the begining. I've also decided to change out the ground wire because I cut it a little short when removing the electronics and there is some sheilding paint on it too.

Where is the ground wire attached? I am assuming one of the post. And what is the best way to replace it?

Thanks,
Eirc

 

[donahue]

Re: Ground Wire On Tune-O-Matic Bridge

Hey bro, I found this out just yesterday. The ground wire should be between the tailpiece bushing and the body, kinda just wedged, for lack of a better term. I also learned something else. To change it, get a claw hammer and a piece of wood to put b/t the guitar body and the hammer, screw in one of the t/p studs, and pull out the bushing like you would a nail from a piece of wood. You'd be surprised at how good this works and how easy the bushing comes out. Look at the hole in the control cavity and try to see where it points, cause it could maybe be under a bridge bushing. To install the bushing again, use a rubber mallet and a couple good taps, should get it right back in w/o damaging your guitar.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

Hey bro, I found this out just yesterday. The ground wire should be between the tailpiece bushing and the body, kinda just wedged, for lack of a better term. I also learned something else. To change it, get a claw hammer and a piece of wood to put b/t the guitar body and the hammer, screw in one of the t/p studs, and pull out the bushing like you would a nail from a piece of wood. You'd be surprised at how good this works and how easy the bushing comes out. Look at the hole in the control cavity and try to see where it points, cause it could maybe be under a bridge bushing. To install the bushing again, use a rubber mallet and a couple good taps, should get it right back in w/o damaging your guitar.

Thanks!

I wish I had something to practice on first! Maybe I have some left over studs laying around... hmmmmm :scratchch

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

Wait, wait, wait, is that the one I sent you? There's definitely nothing wrong with the bridge connection.

Here is how you test whether that is the problem: either use a crocodile clip to attach ground to the strings directly. Or just touch ground at the guitar cable. If the hum goes away the strings were not grounded. Or use an ohmmeter.

Having said that, a lack of string grounding with this partially shielded small cavity would not cause bad hum, just some hum. There must be something else wrong.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

I went at it again tonight and I still getting the same ground hum as I did before the I put the new pots in.


I checked and rechecked all of my connections with a multi-meter, everything looked good.

I went through and heated and then reheated all of the ground solder connections. still getting a hum.

The hum will go away if I turn the volume down to about half or turn down the selected pickups tone control or if both are selected just one of the tone controls.

Also goes away if I touch the strings.

Any ideas?

Maybe I have a with a pickup with broken ground wire?


ps... cable and amp are both good. checked it with another guitar.

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

If it goes away when you touch the strings the basic ground connections including the one to the bridge are OK.

Did you hook up 4-connector pickups? Do you have an ohmmeter?

As you say, it would fit your symptoms if one pickup (4-conductor) wire didn't have it's shield connected.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

If it goes away when you touch the strings the basic ground connections including the one to the bridge are OK.

Did you hook up 4-connector pickups? Do you have an ohmmeter?

As you say, it would fit your symptoms if one pickup (4-conductor) wire didn't have it's shield connected.

Yes I did hook up the 4 connector ones. And I do have an ohmmeter.

I know both pickups are tied to the same ground on the back of the volume pot. Maybe that one is a little cold. I'll try moving some wires around and see what I get.

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

No, the pot will be kosher even if it loosely touches. Contact is contact here, even lousy contact.

Please post a photo of the 4-wire hookup.

You realize this is actually a 5-conductor-wire, right? You need to connect the shield to ground, and one of the 4 wires inside the shield.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

No, the pot will be kosher even if it loosely touches. Contact is contact here, even lousy contact.

Please post a photo of the 4-wire hookup.

You realize this is actually a 5-conductor-wire, right? You need to connect the shield to ground, and one of the 4 wires inside the shield.

I thought green and bare were soldered together and that went to the ground? I have to attach the foil casing to it too?

I took it to the tech. He said that the grounds were solid and the noise I was getting was from using unshielded wires. :smack:

So time to try it again with some shielded cable the tech gave me. I also went through and put some shielding paint in the cavity under the pickguard.

 

[Sporky McGuffin]

Re: Ground Wire On Tune-O-Matic Bridge

Remember to shield the cavity cover as well.

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

Shielded wire inside the cavity isn't required. Helps but really not required. You need to ground the shields in the wires to the pickups and to the 3-position switch. You did correctly in putting the blank wire to ground.

If you shield the complete cavity you don't need to ground the strings anymore. But that's shielding on a higher level than almost any new guitar.

You don't need any shielding in the Explorer's area under the pickguard, as there are only wires going through it that are shielded wires. I recommend that you don't paint that area.

Overall the diagnosis of your tech doesn't make sense.

To summarize:
- shielded wire inside the electronics cavity isn't required, few people do that.
- in the Explorer, the area under the pickguard has nothing to do with the electronics cavity and doesn't need shielding if the wires running through it have their shield correctly grounded.
- shielding the cavity helps but isn't required. If you have strong hum it's not that.

Overall what we need here is a photo.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

Shielded wire inside the cavity isn't required. Helps but really not required. You need to ground the shields in the wires to the pickups and to the 3-position switch. You did correctly in putting the blank wire to ground.

If you shield the complete cavity you don't need to ground the strings anymore. But that's shielding on a higher level than almost any new guitar.

You don't need any shielding in the Explorer's area under the pickguard, as there are only wires going through it that are shielded wires. I recommend that you don't paint that area.

Overall the diagnosis of your tech doesn't make sense.

To summarize:
- shielded wire inside the electronics cavity isn't required, few people do that.
- in the Explorer, the area under the pickguard has nothing to do with the electronics cavity and doesn't need shielding if the wires running through it have their shield correctly grounded.
- shielding the cavity helps but isn't required. If you have strong hum it's not that.

Overall what we need here is a photo.

No. I sheilded the cavity on my own. I added length to the each pickup because the leads wouldn't reach the control pots. When I did that I used unshielded wire and also housed it under the pickguard so I could give myself more room to work inside the control cavity.

The tech said that added length is where the noise is being introduced.

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

Ahhh . Glad it's resolved.

This is why we can use photos, we could have spotted that instantly. Grounded kitchen aluminium foil around the wires will also do.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

Ahhh . Glad it's resolved.

This is why we can use photos, we could have spotted that instantly. Grounded kitchen aluminium foil around the wires will also do.

Well after 2.5 hrs of taking off the old wire and putting the new stuff in I have success!

I need too foil around the cable splices a bit andl around the long leads that go to the switch.

But over all it is really quiet without that stuff.


Edit: Added the foil and its super quiet. Hopefully it will stay that way lol.

uOpt what size strings did you have on it? I'm setting it up tomorrow and want to put the size on that the nut was cut for. 10's?

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

I double checked it today so the excitement of getting it to work wore off and could correctly asess what has been done. The foil did help, but only on the lower clean settings.

I don't think that did the foil correctly.

So grounded foil you say. How did you get it to ground? I couldn't get solder to attach to it. Maybe I need to scrap it a bit with some sandpaper.

How do you correctly insulate using the foil?

Electical Tape, Foil with ground, Electical Tape?

I will assume that you just need enough foil to wrap around the wires once?

Any tips will be much appreciated. I took off all of the foiling I did last night so I can start from scratch and get it done correctly before I move on to setup.

 

[uOpt]

Re: Ground Wire On Tune-O-Matic Bridge

I double checked it today so the excitement of getting it to work wore off and could correctly asess what has been done. The foil did help, but only on the lower clean settings.

I don't think that did the foil correctly.

So grounded foil you say. How did you get it to ground? I couldn't get solder to attach to it. Maybe I need to scrap it a bit with some sandpaper.

How do you correctly insulate using the foil?

Electical Tape, Foil with ground, Electical Tape?

I will assume that you just need enough foil to wrap around the wires once?

Any tips will be much appreciated. I took off all of the foiling I did last night so I can start from scratch and get it done correctly before I move on to setup.

You shouldn't have to use any foil. The wires to pickups and to the three-way switch should be shielded. The cavity is better with shielding foil but if you are willing to use yourself for a shield then you ground the strings and that's that. The Explorer has a very small electronic cavity, so there shouldn't be a noticeable hum when doing that.

If you want to use foil, you just have to touch it somehow. You cannot folder to kitchen aluminium foil. Usually what you do is that you make it touch the pots and since the pot's cases are grounded that grounds the foil.

I have one construct where I solder uninsulated copper wire to a ground place and wrap that around the foil.

Anyway, I think you still have a real problem there. Shielding the cavity shouldn't be required. Touching the grounded strings should quiet the guitar down to almost unhearable.

%%

I had Dean Markley Custom Lite on it, that is 009-046 (the low strings from a 010 set). I did not modify the nut for it.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

You shouldn't have to use any foil. The wires to pickups and to the three-way switch should be shielded. The cavity is better with shielding foil but if you are willing to use yourself for a shield then you ground the strings and that's that. The Explorer has a very small electronic cavity, so there shouldn't be a noticeable hum when doing that.

If you want to use foil, you just have to touch it somehow. You cannot folder to kitchen aluminium foil. Usually what you do is that you make it touch the pots and since the pot's cases are grounded that grounds the foil.

I have one construct where I solder uninsulated copper wire to a ground place and wrap that around the foil.

Anyway, I think you still have a real problem there. Shielding the cavity shouldn't be required. Touching the grounded strings should quiet the guitar down to almost unhearable.

%%

I had Dean Markley Custom Lite on it, that is 009-046 (the low strings from a 010 set). I did not modify the nut for it.

The wires to the switch are not shielded.

Installed the pickups and extended the length of the lead with unshielded cable= original noise problem.

Thought it was a ground (cold joint or a broken wire) took all of the old wiring out, installed new everything= still noise.

Took it too a tech who pointed out I didn't use the shielded cable and that was letting noise seep in. Makes sence looking back because the multi-meter was showing all the signal and ground paths as solid connections.

Used shielded cable to lengthen the leads took care of most of the noise.

However I could not use the original shielded cable that ran to the switch because I had cut it to short.

So I still have a bit of noise because the switch leads are not shielded hence the need for some tin foil because I don't have any shielded 5 conductor wire around that was originally used in the guitar.

The noise is way less that before, but still a noticable amount when I let an open string ring out. And touching the guitar strings does quiet it down to nothing.

Shielding the cavities with the shielding paint wasn't required I did it for my own preference and not trying to fix this noise problem. I most often play around electronics (tv, computer monitors, etc) and I have found that it helps to reduce the interfearence I pick up. (FYI When I am working on this guitar and trouble shooting it I am around nothing that could cause interfearence)

And when I did the foil around the switch wires I forgot the run a foil ground with it. I was in too much of a hurry and wrapped and tapped it. Tomorrow I will make sure to do it correctly. I am sure once that is done everything will be as it should.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

I'm done fooling around with the foil. It did help, but I had about a 2" section I couldn't get to with the foil and still had a tiny bit of noise seeping in. I ordered some 4 conductor shielded cable and will rewire the switch with that.

 

[ericmeyer4]

Re: Ground Wire On Tune-O-Matic Bridge

Gaaaaaaaaaaaaaaaaaaa! Just got a notification that the wire is backordered for the next 2 weeks.