Earth buzz - what to check with a multimeter?

darius

Wiring experts help please...
Got a used EVH Wolfgang and its got quite a bitoif earth buzz crackle hum. Kind of a variable scratchy noise, not familiar to me. eg If i bend a string it varies as the string travels across the fret.
Completely silenced (the buzz is) if i touch the jack plate (exterior) and only if i touch the jack plate.
Everything looks soldered and connected.
Ive got a multimeter.
What should i check and what ohms should i expect across what bits,  to find the problem?
thanks!

gringopig

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ICBM

It sounds like the string ground connection has come off. On a guitar with a Floyd Rose it will usually be a wire to the spring claw.

darius

Its the hardtail version, no trem. But i will check for a bridge to ground wire.

ICBM

darius said:

Its the hardtail version, no trem.

In that case it’s most likely to be just making a poor contact under the bridge. I prefer to poke the end of the wire down one of the screw holes, that usually guarantees a better connection.

Henrytwang

Probably a poor or non existent string ground. With the multimeter on ohms put  one probe on the strings and the other on the jack socket sleeve the meter should indicate a short circuit. If the meter has a continuity buzzer you could also use that to check the string ground connection.

darius

Henrytwang said:

Probably a poor or non existent string ground. With the multimeter on ohms put  one probe on the strings and the other on the jack socket sleeve the meter should indicate a short circuit. If the meter has a continuity buzzer you could also use that to check the string ground connection.

For clarity
there should continuity and low ohms (<1?) between strings and the Sleeve of jack socket. Correct?
if open circuit or high ohms (>100?) then problem is somewhere between bridge and jack.

And my thought is that sleeve of jack socket is easiest access by using the other end of a TRS cable plugged into the jack socket. Or is the jack socket plate connected to sleeve  Even easier?

ICBM

darius said:

For clarity

there should continuity and low ohms (<1?) between strings and the Sleeve of jack socket. Correct?
if open circuit or high ohms (>100?) then problem is somewhere between bridge and jack.

Correct. But if the guitar works and doesn't hum loudly - which would be the case if the ground wire had come off at the jack - then it's almost certainly at the bridge - unless the bridge ground wire has come off the back of the volume pot where it's usually soldered to, but that would be visible inside the cavity.

darius

Ok. Checked and confirmed. Open circuit from strings to ground. Everything else checks out ok.
The wire is in the cavity, I'll undi the bridge and hopefully reattach it.
Forum wins again.

darius

And no. Ok. Totally weirded out now.
The individual saddles are highly resistive preventing continuity.
Ground wire conductive to steel insert fixed in body.
Threaded Bridge Post is conductive to steel insert when screwed in.
Tonepros bridge is conductive to bridge post when placed on posts.
Bridge conducts to ground.
but
Each saddle in the bridge is not conductive to the bridge. So the string cannot ground through the saddle to the bridge. The little threaded stud each saddle runs on (intonation adjust) are conductive. The connection is breaking between the saddle, their stud and the bridge. But its all feckin steel so what the actual feck?

Any help?

 Is this a known Tonepros thing? Ive never owned one. 

mbe

If you could get a ground connection to the stop bar tailpiece that should do it.

darius

mbe said:

If you could get a ground connection to the stop bar tailpiece that should do it.

No access. Solid body, no cavities, no way to connect to the inserts.

ICBM

How very strange, if the saddles appear to be metal! Obviously the old Gibson ones with nylon saddles and modern Graphtech ones aren’t.

If you can’t get to the bottom of it, replacing the bridge with one with definitely conductive saddles might be the only option. 

prowla

String to jack socket sleeve should be 0 ohms.