Ground wire the culprit?

[diablo175]

Here's a question for those with a solid working knowledge of guitar electronics- My Gibby LP Axcess w/ Floyd Rose thas been humming excessively lately. Started to do this last year during a show. I've since dug into it and even had a pro take a look, trying to uncover the reason. He claimed he found nothing and couldn't get it to hum and feed back as I did on my rig.

I ended up tweaking a few levels on my FX unit and that seemed to to do the trick... for a while. Now it's back to humming and I swear it's a ground issue. So, I took the back off the control cavity and the trem cavity and there's no f-ing ground wire going to the trem spring claw. Is it safe to assume that this is what's at issue? Can't still figure out why it took several years before it started to hum like this.

Thoughts?

[cynic]

With as many OFR's as Gibson installs, my guess is they stuck with routing the ground to the bridge post per their normal.

eta: I think if the ground wire leaves the control cavity significantly deeper (where the hog meets the maple) than the back rout for the Floyd, it's probably a good indication it's going to the post.

[Jeff R]

Sounds like no ground wire to claw. Without going all crazy with the job, you may just take a spare long piece of wire, and see if you can tie it and/or tape it around ground on the claw (unused spring tongue) and on a ground connection in the cavity (maybe electric-tape it to a pot housing). You don't even have to run it through the body cavity, and that should answer the question in no more than 2-3 minutes with no evidence of solder tampering.

[diablo175]

With as many OFR's as Gibson installs, my guess is they stuck with routing the ground to the bridge post per their normal.

eta: I think if the ground wire leaves the control cavity significantly deeper (where the hog meets the maple) than the back rout for the Floyd, it's probably a good indication it's going to the post.

Hmm. I pulled the stock MIK POS Floyd outta that a year ago and replaced it with a genuine OFR but I don't recall any ground wire at that time nor did I see any ground running from the pot to that area. I'll pull the post out and look again.

[cynic]

My Gibby LP Axcess w/ Floyd Rose thas been humming excessively lately. Started to do this last year during a show.

Hmm. I pulled the stock MIK POS Floyd outta that a year ago and replaced it with a genuine OFR but I don't recall any ground wire at that time nor did I see any ground running from the pot to that area.

Coincidence?

[diablo175]

Probably not.

[Armitage]

Guitars that have (or had) EMG or similar active pickups don't have a grounded bridge... does it or did it have EMGs etc? Otherwise the strings should be grounded.

[diablo175]

Armitage- they're passives.

As Cynic noted, Gibby has a different way of running the ground wire- instead sending it to the claw arm, they send it to one of the bushing on the Floyd bridge. I pulled one of the posts and looked down the (rabbit) hole and sure enough, there was a wire all the way at the bottom and presumably it was the same wire that came out of the p'up lead rout and soldered to the one pot. I gently pushed it to ensure it was making contact with the bushing and then put the Axcess back together and tried it- NO luck. Still humming/buzzing rather loudly. But only at higher (gig/live rehearsal volume levels). I'm stumped.

[Jeff R]

But only at higher (gig/live rehearsal volume levels).

That opens a host of possibilities, considering it's not a guitar grounding issue (or seems not to be). Wiring/lighting in the room where the high volume is applied; poorly shielded cable(s) somewhere between the guitar and the amp; AC disagreements between stuff on pedalboard, the list goes on.

If you're seeing similar problems with other axes, Jim, start w/guitar-main cable-amp and slowly integrate pieces of the puzzle one by one to isolate the culprit(s).

If it's only the LP that's doing it, try my external wire trick and see if that helps - you can't "over-ground" the internal circuit and it may help. I have no idea what type of metal the FR bushing is made of, but it could just be a poorly-conductive alloy, just a thought. We know (or fairly assume) the claw, springs, trem block and base plate together are sufficient conductors.

[velorush]

You can't "over ground," but you can create a ground loop and make the whole thing into a noise antenna. I'd want to know whether the ground is really effective by checking for resistance from a known point of ground to the strings. I'm guessing the strings are connected, but not effectively. One path to ground and make it a good one.