My Jackson has had this pesky scratchy noise for a while. Been driving me nuts, to the point where I'd not play it. Even after replacing one of my pups and redoing part of the wiring I still had this scratchy noise.
Open up the electronics cavity again, poke around, resolder a wire or two. Still didn't go away. Unwired EVERYTHING again, soldered it all back together. Same thing.
Only thing left was the input jack itself. Plus I got to thinking about it. The only time it would make the noise was when my guitar would move around, indicating that something was wrong with either the cord itself or the jack. Swapped cords, didn't solve it... Had to be the jack.
Went to local guitar shop, got a new one, put it in last night and wala... Problem gone.
How? How can a jack be the problem? They don't do anything. No moving parts. I looked closely at the jack, nothing was touching that I could tell which might cause some kind of grounding issue.
Anyway... Moral of the story, don't overlook the input jack as the source of an electrical issue.
[U]Ricks Current Mystery Video[/U] - Updated Monday March/02/2015