Hum Help Please 2 Guitars Same Problem

[shortfuse]

I think there is a black cloud above me this week.  I have 2 guitars that have the same exact problem and are completely different guitars.  And nope not the amp or outlets because all my other guitars are fine through the amps and these 2 guitars do the same thing no matter what amp they are in.

Guitar 1
2 - P90's Fralin in the Bridge, and Lollar in the neck, both 2 conductor with the braid over ground style.  Standard Fender 3 way switch.  2 vol 1 tone.  Now this guitar has always been a bit noisy I just caulked it up to the P90's.  It is now unbearable in the neck or bridge position and fairly quiet in the middle position or i should say the same noise level as it always has been.  I have replaced everything pots, switch,  wire & removed treble bleeds.  I have tried taking an alligator clips and physically grounding components to no solution that works.  I even wired it up as a single pickup guitar utilizing 1 pot jack pot PU same noise.  But again when all wired up in the middle position it is quiet.  This did not happen over time last time I used this guitar (month ago) it was fine. 

Guitar 2
Brand new Salsh LP.  Has Seymour Duncan Alnico II Pro Slash APH-2 same style wiring as above 2 conductor braid over ground style.  Now this guitar is brand new less than 6 hours on it.  Played it at the store about and hour but never cranked the amp.  Took it to band rehearsal 5 hours and Holey Buckets this sucker hums, the boys were wanting to put a bounty out on me.  Same issue in the middle position quiet in bridge or neck position hums like an SOB.  After I checked it out with a multi meter at home and could not find anything I took it to my friend shop who is a warranty center he looked it over deemed it the selector switch but did not have one in stock and it would be stuck in line to be repaired for 3 weeks.  I am on the road working again so i opted to buy a switch and install.  I bought a tall switchcraft switch and installed, nothing changed.  I noticed when I moved the shielded cable that runs from the pots / input jack to the switch it made a crackle noise.  I had a 4 conductor with shield and bare ground LP style in the spare parts box replaced it as well and no change.

My thought is grounding issue in both, cant find it and there really is not a whole lot to check.  But I am obviously overlooking something.  Not quite sure how to thoroughly check out the PU's themselves.  I couldnt possibly have bad pickups in both guitars, could I?.  I am stumped.  Will post some gut shots tonight.

[sluckey]

Are you using the same instrument cable?

[shortfuse]

No several different ones.  Amp at band room I have 3 different 20' cables tried switching between the 3.  Home is random but I did try different cables.

[shortfuse]

Here are some gut shots

[HotBluePlates]

Get a meter, put it in continuity mode. Touch one lead to the strings on the Slash LP, and the other lead to one of the pot bodies (or even the sleeve of your guitar cable plug). Get a beep?

The Gibby is probably alright, but doesn't have solder joints on the braid in the same way I did them when I worked at Gibson.

On your other guitar with 3 controls (assuming this has the P-90's), how are the braid portion of the pickup wiring grounded? There's mondo-excessive wire length, and there are simpler ways of wiring it that preclude the need for the extra bits of wire connecting the pot bodies in this guitar. I presume the P-90's will hum/buzz to some extent no matter what because they're single coil.

The easiest way to wire this 2nd guitar is like so: Unsolder the pickup wire going to the pot closest to the hole where those wires pass through the body. Lay it flat against the pot and cut it so it has just enough length to reach down and through the pot lug for this wire's hot lead. Push the braid back a little. Lay the other pickup lead flat alongside this first wire, and down on that first pot body. Use a ~40-60w iron to heat the braids of both, and flow solder onto the pot body (when the pot is hot enough to melt solder all on its own). Hold the wires in place with a screwdriver, etc and remove the iron until the solder cools. The solder joint should be so strong you can lift the entire guitar by pulling up on those pickup wires. Now run the other pickup lead over to its pot, and similarly trim to length, then solder the hot lead in place and finish by soldering the braid against the pot body as before.

So both braids get soldered on the first pot body, and only the 2nd pickup's braid gets soldered on the 2nd pot body. Usually, the string ground wire lays right against one of these braids when they're soldered to the pot body, though you might solder it to the 2nd pickup volume and run it over to the tone pot, etc. Gibson uses those nifty ground plates to both establish a ground among all pots and to spped installation.

[shortfuse]

Thanks HBP your description of rewiring the P90 guitar makes complete sense and I will try it out maybe the shorter ground length, tidy + lead length and dress per say will help decrease some noise.  And yes the P90's always were a bit noisy a bit more than the strats but I always chalked it up to that's the way they were.  I think I have seen a few older 335's done that way.  After Sluckey's comment on the cable and my 2 guitars I have with me on the road are doing the exact same thing made me think a little deeper. 
The problem is not the guitars I think I have a problem in both my DSL50 in my apt, and rack unit at the band room (which has a Marshall JMP-1 and Peavey 50/50 power amp).  I am working out of town and keep an amp in both places so all I have to tote to rehearsal is a guitar.  But I may have messed up the Peavey power amp by having it set up wrong I will post my issue in the amp forum later. As far as the DSL is concerned I am clueless right now and have not had time to check it.  But last night I went to the house picked up my Diezel head to use at rehearsal and the LP was fine and P90's were at their usual noise level.
I never would have though I had a problem with both amps at the same time causing the same type of issue but it seems that is the root cause of the problem.
I will repy back after I rewire the P90 guitar as described above.
Thanks