Definitive way to check for bad ground?

[astrozombie]

I've made great progress when it comes to installing and removing pickups. With the help of a new iron, i've been able to do a bunch of jobs perfectly. However, I have to ask: is there a definitive way to check for a bad ground connection in a guitar? I think I had read something here once about using a multi meter? I ask because today I put some pickups in a guitar, and went to test it. I plugged the guitar into my fender deluxe, and put the amp on the clean channel. the pickups themselves sounded wonderful: full and clear. However, I noticed a slight hum. I switched over to the overdrive channel, and the hum got a tad louder, but it wasnt that bad. pickups sounded good. I switched to the distortion channel, and got louder noise. the noise itself isnt too loud. it's only noticeable when i'm not playing. touching any metal part such as the control plate or jack, did not make the noise louder, or quieter. I tried a different cable, and got the same result. when I plugged into my peavey 212, the guitar barely gave any noise when I wasn't playing, much less than the fender. I'm not sure if the noise is particular to the amp, or if the guitar does indeed have some fault in it's wiring. if it makes a difference, the pickups are humbuckers and they are not high output. they are both 8-9k.

 

[CTN]

Re: Definitive way to check for bad ground?

does your fender have a ground lift function at all?

 

[surface54]

Re: Definitive way to check for bad ground?

im having the same problem in a way. after playing when i mute the strings wth my palm there is a sort of hum, but when i move my hand away from the strings and mute them with my other hand highup on the frets it goes away. another thing when i touch the poles with my finger on the bridge pickup the hum gets loud, but when i switch to the neck pickup and touch the poles nothing happens. does this mean theres a ground problem in the bridge? i went over it all again yesterdaty making sure all the solder was solid. it was. maybe its just someting i never noticed before. i dont think so though.

 

[TREW]

Re: Definitive way to check for bad ground?

AZ,
you can use a multi meter by setting it in the ohm reading. touch the leads together and make sure you get a deflection on the meter. I dont know what kind of Git ur using, but get to the underside of the controls or pu's and check for continuity between all ground points--body of pots- bridge and ground wires coming off pu's. You can line the cavities with copper tape and solder a wire from the back of a pot to the copper tape. Make sure ALL copper tape is touching each other(for continuity). I just did this on a Squire standard Strat and cleaned up really nice.

Dan

 

[King IzzO)))]

Re: Definitive way to check for bad ground?

The definitive way to test is to take your meter on the ohm setting and check from the bridge to the ring on your output jack, should be 0.0 (make sure you are picking a spot on the bridge where the coating has been removed). If that is good test from your pickup baseplates/covers to the output jack. If all is good your amp is connected to a bad ground or you are just picking up noise in which case shielding is all you can do.

 

[surface54]

Re: Definitive way to check for bad ground?

did even further tests to find that the 1/4 jack was getting sparse in its connection, so i cut it off and spliced more line, then resoldered it, no more hum. i was worried it was the pickup.

 

[astrozombie]

Re: Definitive way to check for bad ground?

does your fender have a ground lift function at all?

No.

 

[astrozombie]

Re: Definitive way to check for bad ground?

The definitive way to test is to take your meter on the ohm setting and check from the bridge to the ring on your output jack, should be 0.0 (make sure you are picking a spot on the bridge where the coating has been removed). If that is good test from your pickup baseplates/covers to the output jack. If all is good your amp is connected to a bad ground or you are just picking up noise in which case shielding is all you can do.

so if i get a reading higher than 0.0 between to connections, thats the ground i need to revise?

 

[Jessie Sammler]

Re: Definitive way to check for bad ground?

The only definitive test for a bad ground is a liver biopsy.

 

[astrozombie]

Re: Definitive way to check for bad ground?

i used the info to check out a guitar I'm working on. it's 1 humbucker one volume. the guitar hums when i take my hands off the strings. it goes away if i touch the bridge.

im supposed to put the positive lead on the bridge and the black one at the ring right? doing that gets me a reading of 00.3k.

since im not sure where i was supposed to put that lead i checked it with the black at the bridge and the red at the ring. i got the same.

from the volume pot to the ring on the jack gets me 00.1k

this means the ground is good right? what else can I check?

 

[Funkfingers]

Re: Definitive way to check for bad ground?

The definitive way to test is to take your meter on the ohm setting and check from the bridge to the ring on your output jack, should be 0.0 .

This will, indeed, confirm that you have a path to ground via the jack socket. It will not definitively test for ground loops and other problems within your ground circuit.

Regarding the pickup/amp hum issue.
1) No dual coil pickup is absolutely, one hundred per cent, perfect at cancelling hum.
2) Increasing levels of background noise are inevitable with increased pre-amp gain.
3) The big difference between the Peavey and Fender amplifiers is the size of the transformers in the Fender HRD. Transformers are a source of interference. Stand further away from your amp or get a noise gate pedal.

 

[astrozombie]

Re: Definitive way to check for bad ground?

This will, indeed, confirm that you have a path to ground via the jack socket. It will not definitively test for ground loops and other problems within your ground circuit.

Regarding the pickup/amp hum issue.
1) No dual coil pickup is absolutely, one hundred per cent, perfect at cancelling hum.
2) Increasing levels of background noise are inevitable with increased pre-amp gain.
3) The big difference between the Peavey and Fender amplifiers is the size of the transformers in the Fender HRD. Transformers are a source of interference. Stand further away from your amp or get a noise gate pedal.

1) I understand that completely. However, this isn't the normal hum you get from using distortion. it's a sort of buzz sound. Like when you touch the lead connected to your amp and you get that BUZZZ, but a tad quieter, and it goes away when I touch the strings.

2)I am not using that much gain. I'd dare to call it overdrive.

3) This I have to see...


edit

All of this guitar wiring stuff aside... it could be the amp itself right? or the way the amp is reacting to the circuitry of my home? I hadn't tried another outlet because I have the hot rod deluxe on a cab and was lazy... I'm going to try in a few.

 

[astrozombie]

Re: Definitive way to check for bad ground?

ok so right now im trying to find a bad ground on my flying V. when putting one lead on the base plate of my pickups and one on the ring on the jack, i get a reading of about 00.8.

this means my pickups are grounded correctly right? well, if i put one lead on any of the pots, the reading changes. on one pot, the multi meter goes nuts and slowly rises until about 15.00 then goes back to 0 and cylcles again. What does it mean when the multi meter does that? bad ground?

there is only 1 ground wire coming from the bridge. the two humbuckers are one conductor and are grounded by the back of a pot, not the one with the ground wire. the pot with the ground wire attached to it also goes nuts.


edit
OK, so this is really weird. if I put a cable in the jack, and put one lead on the tip of the cable in the jack, and the other on the baseplate, I get that weird 0-15 cycle.

 

[ehdwuld]

Re: Definitive way to check for bad ground?

ok so right now im trying to find a bad ground on my flying V. when putting one lead on the base plate of my pickups and one on the ring on the jack, i get a reading of about 00.8.

yeas grounded direct connection

this means my pickups are grounded correctly right? well, if i put one lead on any of the pots, the reading changes. on one pot, the multi meter goes nuts and slowly rises until about 15.00 then goes back to 0 and cylcles again. What does it mean when the multi meter does that? bad ground?

thats your cap on your tone pot doing that

there is only 1 ground wire coming from the bridge. the two humbuckers are one conductor and are grounded by the back of a pot, not the one with the ground wire. the pot with the ground wire attached to it also goes nuts.

I dunno
is your tone pot grounded?
you should have two wires from the tone
one ground going to the volume pot
and one coming from the wiper terminal to the volume pot terminal
EDIT
the ground should be back of tone pot to back of volume pot

OK, so this is really weird. if I put a cable in the jack, and put one lead on the tip of the cable in the jack, and the other on the baseplate, I get that weird 0-15 cycle.

again the cap

no ground from tone to volume