static & crackle after QTB mod

[radrobot]

I feel like the needy newbie.

Finished the QTB mod and assembled everything back together. Plugged the strat into an amp and everything sounded great. But after a few minutes of playing I started to hear this very subtle static sort of sound. I pushed down on the pickguard and it went away.

Pushing around on the pickguard some more I get the static/crackle noise when I push under the neck and middle pickups. There is no noise while I'm playing, just when I push on the pickguard.

I'm assuming something is touching the copper shielding in the cavity that is not suppose to. I took the strings off and removed the pickguard. As far as I can tell there is nothing touching around the neck and middle pickup.

Not sure if this was wise, but I plugged the pickguard into the amp and started moving wires to see if I had a bad connection. Everything seems to be properly connected.

Frustrated.

Anyone have any advice?

[JohnH]

radrobot - in this "pushed in" position, do all of the controls still work as they should?

If so, it could well be that the shielding on the pick-guard is not connecting cleanly to the cavity shielding, except when you press down. The cavity foil should lap up a little over the top of the cavity, so that when the top is screwed down, it contacts with the pick-guard shielding.

I'm suggesting that because in one case, I noticed that as I lowered the pg assembly down onto the cavity, with amp connected, there was a crackle as the two foils come into contact

John

[radrobot]

johnh said:

radrobot - in this "pushed in" position, do all of the controls still work as they should?

If so, it could well be that the shielding on the pick-guard is not connecting cleanly to the cavity shielding, except when you press down. The cavity foil should lap up a little over the top of the cavity, so that when the top is screwed down, it contacts with the pick-guard shielding.

I'm suggesting that because in one case, I noticed that as I lowered the pg assembly down onto the cavity, with amp connected, there was a crackle as the two foils come into contact

John

Hey John.

Yeah, I lapped over the shielding from the cavity. It seems it should be making good contact. I checked everything over, and now it seems as if there is no grounding going on whatsoever. I think I'm going to rewire it again.

[radrobot]

Please help... anyone.

I rewired the star grounding using a ring terminal (originally I just had all the ground wires twisted together). I also noticed that I did not twist the shield braid on the audio cable to the ground wire connected to the jack. I fixed this thinking this might solve my problem.

I get no static or crackle now - just a light buzz. When I touch the jack plate the buzz goes away. If I touch the bridge the buzz gets a little louder. If I touch the selected pickup, the buzz gets real loud.

Anyone have any suggestions as to what is going on here?

I'm not a pro at this stuff, but I'm not a novice either. I've done many a successful mod and wiring project, but this one is driving me crazy.

With everything I've done, this strat sounds just like my other unshielded strat. When I touch the jack plate on either guitar the buzz goes away.

I've used my meter to check continuity of the shielding in the cavity as well as on the pickguard. I've checked all my wiring over and over again.

This strat is wired with the back tone knob as a blend knob and the middle tone knob as the universal tone. There is a cap on the middle tone knob with one lead going to the pot terminal the and other lead going to star ground. There is also a volume mod with a 220K resistor in parallel with a 471pf capacitor wired from one volume terminal to another (helps preserve high end when rolling back volume). Other than that, everything is a normal strat.

Not sure where to go from here. Thanks for any help.