Weird Buzz/Hum - apparently ground problem, but not sure how that could be

[BrotherJack]

EDIT:  I think this one is solved guys - nevermind  (though the strat I describe below still buzzes more than I like and I don't know why).

Hi Guys.

I have shielded and/or wired up, oh, 20 or 30 guitars at this point.  All of them came out more/less dead silent (or at least very quiet).  Some were shielded cavities, some were just carefully run shielded wires, all resulted in either dead silent (more so than I ever thought a passive pickup guitar could be) or nearly dead silent guitars.  All of a sudden, the last two guitars I've worked on, have this HORRIBLE buzz/hum (almost as loud as the sound of the guitar) that is driving me crazy, because I don't understand what the deal is, and I'm hoping one of you smart(er than me) people can help. 

Buzz description:  loud, very loud.  When strumming the guitar, it's almost as loud as the sound of the guitar.  It does reduce in volume when I touch metal/ground, but gets louder if I put my hand near the pole pieces on the pickup without touching the strings.  Since my touching ground affects it, it would seem like classic ground problem, but I've continuity tested all the things (including cables, jacks, etc), and there is great (near 0 resistance) connectivity along the entire ground circuit.

Of the 2 guitars I have that have this issue, one is a strat, and one is a hollow body, both humbucker equipped.  For the strat, I ended up copper foil shielding it in every conceivable way, including inside the output jack cavity, and I even used a short bit of shielded cable to make the run between the pickup/control cavity and the output jack.  All the wiring in the control cavity is correct (or at least the same as I've done all  my other guitars that don't buzz at all), yet it still has a fairly high level of noise when I plug it in.  After all the shielding it did reduce somewhat to a level where it's tolerable (though still remarkably present), but I don't get why is it not dead silent like all my other guitars?  I have a multi-meter, and I checked the ground continuity to the shielding, the jack, the cable, etc, etc, etc, all had essentially 0 resistance (ie: great conductivity).  It makes no sense to me that this guitar would be noisy in any way.

Second guitar is a hollow body, so shielding the cavity isn't an option, but it has shielded wire everywhere which is (should be) almost as good.  I played this one for a year or so before taking it apart to work on it, and it did not buzz to any noteworthy degree with the stock pickups in it, and it did not buzz after I swapped in a Pearly Gates in the bridge slot.  However, now after having it apart and putting it back together (see my thread in the work in progress forum), it now has what seems to be the exact same problem as the strat did.  The only difference in wiring from the way it was before (more/less buzz free) is that it now has a different neck pickup (which I did wire out of phase with the bridge accidentally - I will be fixing that), and the shielding/ground between the switch and the volume pot had come loose at the switch end from handling and what remained was a bit short to try and solder back in place, so I soldered in about a 1 inch section of 20 gauge wire hanging off the switch and stuck the ground for both pickups and the shielding/ground going to the volume pot to that little extension.  That's it - everything else is the same as it was when I took it apart - same wires, same solder joints, same everything.  edit: oops, and I added a treble bleed cap+resistor on the volume pot, that's also new.

Any of you can shed some light on what I'm doing wrong?  If I didn't have other guitars that were dead silent when plugged into the same gear, I'd be hunting for something in the environment about now (dimmer switch, etc), but I can pull the jack out of the buzzy guitar and plug it into one of my others, and boom - dead silence.
:icon_scratch: ??? :icon_scratch:

Thanks in advance for any assistance you can offer.

 

[TBurst Std]

I'd check to make sure:
Leads aren't reversed on the outpu jack
That some stray solder isn't causing it. I had a similar issue, and was some stray solder on the output jack.

 

[BrotherJack]

I'd check to make sure:
Leads aren't reversed on the outpu jack
That some stray solder isn't causing it. I had a similar issue, and was some stray solder on the output jack.

What was the stray solder doing that caused it - providing a near-connection between hot and ground?  I suppose there may be something like that that's happened elsewhere with a blob of solder (I'll look it over  with a magnifying glass later on to see), but the output jack leads weren't touched when working on it (the output jack never came out of the guitar actually, so I'm confident it is in good shape.

 

[BrotherJack]

More report. 

So, looking each connection over carefully, I do see the other end of the ground/shield wire that comes from the volume pot to the switch (the one that came loose on the switch end) looks to be frayed and not holding on by that many strands anymore on the volume pot end.  I also found that the guitar will go dead silent (like dead silent but the pickups are on/working - exactly as it should be) if I touch the ground lug on the switch to the tailpiece of the guitar (even if I am not touching the strings or any other ground point) (which I don't entirely understand, because I don't see any internal wires that would seem to ground to the bridge, but.... results is results).   

So I think at the very worst, I have to figure out a way to get connection from the bridge to ground (though that may be a pain, as it doesn't look like it has a wire from the bridge to the cavity as shipped from the factory (but then why would touching the ground lug to bridge help?!?!)).    At the best, I've identified that I have a poor ground connection between switch and volume pot and a re-solder of that connection (actually, I'ma replace that whole section of wire with brand new shielded wire), and I should hopefully be OK.

That said, any more feedback on the subject is welcomed and appreciated.

 

[BrotherJack]

Ahhhhh.... there it is.... I pulled the tone knob all the way out again (I had just the vol and switch sitting outside the cavity), and boom - there is indeed a wire coming from the bridge that connects there, and the wires where the ground/shield that goes from tone to vol must have been down to their last strand, because they broke loose entirely as I pulled the tone pot out.    (in my defense, these were soldered so tight to the body of the pot that you really can't see the where the wires connect for the rubber insulator).

Nevermind (I think) - problem (I think) solved (or will be (I hope) once I replace these aging wires with nice new insulated wire runs).

 

[BrotherJack]

Yep, rewired the whole thing, and whatdyaknow, fixed it up just fine.    :bananaguitar:  Maybe I can wire a guitar after all.    :icon_thumright:

 

[pabloman]

I was going to put my money on the paint job. As soon as I saw the Texas flag I just new that thing would now be loud and obnoxious! :icon_jokercolor: :icon_biggrin:

Glad you got it fixed. You did a great job on it.

 

[rgand]

Yep, rewired the whole thing, and whatdyaknow, fixed it up just fine.    :bananaguitar:  Maybe I can wire a guitar after all.    :icon_thumright:

Good fix. Thumbs-up!