Arrgghhh! Guitar won't ground

[adamj]

I'm at a loss. My guitar won't ground properly.

I've got it all wired, pickups work.. pickup selector works.. but there's that damn hummmmmmmmm
It goes away when I touch any metal part connected to the guitar.. even the jack plate.

I've followed this diagram exactly:
http://www.seymourduncan.com/support/wiring-diagrams/schematics.php?schematic=lilhum_sing_lilhum_1v_2t_5
(only difference is my jack input ground is going to tone pot 2...)

I've been tinkering away at this for awhile but I'm just stumped and frustrated.

Here's a pic attached.. hopefully someone can spot something that I haven't, or at least give some tips or common ground problems
thanks!

 

[dbw]

There's one critical wire that's NOT on that diagram (or your guitar from what I can see)... you need to run a wire from the BRIDGE to ground (say, back of a pot).  If it's a trem you can solder this wire to the spring claw; if it's not just squish it between the bridge and the body.  Either way Warmoth bodies have a hole drilled for it.

I'd bet good money this is the problem!

An unrelated issue... looks like you UNshielded the pickguard.  Any particular reason?  :icon_scratch:

 

[DiMitriR33]

all guitars hum when you don't touch metal bits on them. some more than others it depends on your sheilding and pickups.
a little advise, don't go so crazy with sheilding, just a peice of foil on the control area of the pick guard will do and at times i dont even do that!

with the foil, if you keep all the pots tight the grounds between the backs of the pots aren't nesesary. this will mean less soldering on the pots and less oprotunity to burn them up. also makes soldering easier. some of the solder joints for your grounds look alittle cold, get a good iron, i like 45watts or better for the pots, 15-30 for all else. i'd start over with brand new pots, sand them and use a very hot iron and the right solder, there are diferent heat ranges.

make sure you ground the bridge. if it buzzes when you take your hand off the strings that is normal.

 

[adamj]

Thanks for the replies.

1. Okay, so the only grounds being soldered to the back of the volume pot are: bridge, jack, pickups, volume

2. the foil on the back of the pickguard could act as a ground? ex. I tightly screw the pots in, thus they're all touching the foil
(and about me scratching it away, I thought it was doing this exact thing and creating a ground loop hehe)

I guess I'll just start from scratch and resolder with the things you guys pointed out.
thanks

 

[bpmorton777]

I would vote for the old "ground loop created by the shielding problem". I did this on a guitar once. You've got the pots grounded with the wires and a second set of grounding by the foil on the pick guard. What I did was scrape away the foil where the pots touch the pickguard...problem solved.

Brian

 

[dbw]

Scratching away the foil was smart in that it avoided creating ground loops with the ground wires on the backs of the pots.  But the better solution is to leave the foil and don't put the wires on the back of the pots, as Dimitri said.  That way your electronics are still shielded (cutting down on hum) but you won't have ground loops.  That said, once everything is grounded, if there's not too much noise then don't bother.

If you don't have an ohmmeter or multimeter, pick one up at Radio Shack, they're dead useful... that way you can check that all the parts that should be grounded, are.  For instance, the strings --> jack plate should have almost zero resistance.

 

[bpmorton777]

in my case I shielded and grounded the whole cavity and there was lip-over where the pickguard was screwed onto the top of the guitar thus grounding the pickguard shield as well.

Brian

 

[DiMitriR33]

what is the theory behind ground loops?
really i don't get it. i've done redundant grounding in the past without noise issues, but so many people here say these ground loops cause interference, i don't know about that but if someone has an educated explaination for me please tell me.

and i don't get all the trouble guys go through to sheild the whole cavity. my strategy lately is to use what ever i have around. either cat 5 cable or an old set of headphones. i use the braided sheilding to conect grounds between components. or one wire from the twisted pair in the case of cat 5. the metal case on the pots will sheild them. and grounding metal bits on switches can't hurt.

my latest creation is a telecaster with a p-90 in the neck, it is loud! and i have no metal foil whatsoever in the cavity. it makes no noise, practically none at all. exept for some feedback issues at extreme volumes do to the hollow construction. it has a 1-meg pot and no tone so there isn't much of a path to ground to bleed off interference. but this is just my experience.

 

[dbw]

Ground loops are excellent antennas so they can be very noisy.  Of course if the cavity is shielded there will be less of a problem.

 

[Alfang]

Sorry about this in advance,

If your wiring was house wiring, your house would burn down.  I don't see one good solder joint in the entire picture, and the insulation on some of the wire is cracking and falling off. And do I see an electrical tape joint there too? or is that an insulator?

Besides the bad hum, I'm surprised you get any sound at all. You need more heat on those joints and hold things steady while the solder solidifies. Don't worry about ground loops, thats all BS just ground all your non signal path parts

 

[TroubledTreble]

Sorry about this in advance,

If your wiring was house wiring, your house would burn down.

:laughing3:

That's funny Alfang! Yeah it could be a bit neater. Fortunatley there's no high voltage. Some practice would be helpful. Since this is not something many people do very often a little warm up is good practice.

The middle tab on one pot and the bottom tab on the other could be aligned and bent over to touch each other.

The two middle top tabs on the switch are wired together. I can only guess that is correct for that switch. It does not match the diagram.

That orange cap is pretty loose and may cause unwanted noise if it grounds on the tab side. It could be soldered directly to the connections without the short wires.

I didn't see your volume pot at first. The tab that connects to ground could be bent back to meet the pot directly instead of using a small wire.

It's usually best to "tin" all connections and wires prior to soldering them together.

All in all I think it's a decent job. I am not picking on it. I thought it would be great to use a tool for all of those who don't do these types of hookups very often or ever.

If  you run a wire from the bridge to the back of a pot everything should work fine. Oh one more thing. I noticed that the wires from the jack are the same color. Are you sure they are hooked up in the correct order. Can't tell you how many times I made that mistake before switching to two different colored wires. :doh:

Best of luck and don't be afraid to go over it again.

-TT-

 

[dbw]

If your wiring was house wiring, your house would burn down.  I don't see one good solder joint in the entire picture, and the insulation on some of the wire is cracking and falling off. And do I see an electrical tape joint there too? or is that an insulator?

This is not house wiring though, the voltages and amperages are so low that even a very weak solder joint is fine.  It's clearly an amateur job but I'm sure all those joints work fine.

 

[DiMitriR33]

a weak solder joint is never fine

fix it and i'll bet he finds the noise is gone

 

[dbw]

Maybe you're right.  Personally I've never encountered a weak solder joint on a guitar, I was just guessing.

 

[Zionplayer]

Do Emg active pups, NEED shielding tape in the body cavity?

I am at a stopping point in my first build due to awaiting  very S L O W  (12 days) shipping......Ebay copper tape shipping.

So, do active electronics require the same shielding as passive electrionics.

Thanks

 

[dbw]

Hehe, Zion, you don't need to ask the same question on every thread with the word "shield" in it. 

 

[Zionplayer]

OK!

 

[wingtip4]

Sheilding is always good but do the whole cavity all the way up and I do the input jack cavity too.  You have to have a least one place where a pickup screw comes in contact with the sheilding  coming up over the lip.  A guitar won't buzz like that when taking off your fingers from the strings unless you don't have the bridge grounded, unless you're picking up something screwy from the wiring in the house.  If you do the full sheild, you can't let the switch or pots touch it in the cavity.  If it's a close fit, put a piece of electrical tape over the pots and switch so they don't touch.