Re: Squier Bass Wiring Issues
It sounds to me like you need a complete shielding/grounding job. You can do it yourself, and it won't break the bank. A 100' roll of 10mm copper tape with conductive adhesive can be had for
$6 on ebay.
One thing I would advise is to take care of your bridge ground before you do anything else with the shielding. What I do is lay a foundation of copper tape that is the same shape as, but just a hair smaller than, the bridge -- taking care not to overlap any tape, so the bridge has a perfectly smooth surface to rest on. Then I solder the ground wire to the copper tape, and leave the other end hanging in the control cavity. I poke some small holes in the copper for the screws -- I make them small so the screws will thread themselves through the copper, thereby helping to ensure the conductivity. Then the bridge is ready to be mounted, and I can carry on with the rest of my shielding.
When you lay your copper tape down, make sure you press down on every bit of each piece of tape, to fully engage the adhesive. In the control cavity, you can overlap all you want, and it's far better to have multiple layers than it is to miss a spot. When I'm done laying the tape, since I like a clean looking control cavity, what I do is solder the bridge ground wire along the bottom corner of the control cavity. I check to make sure the bridge ground is indeed connected, then I put more copper tape over where I soldered the wire in the cavity, rendering it invisible.
For the top of the cavity and the pickguard, some people use tabs. I like to go out all the way around the cavity, out to just beyond the pickguard screw holes. On the pickguard, I like to go out almost to the edge. This ensures full shielding contact all the way around the cavity, and it gives the pickguard a uniform surface to rest on.
To finish it all off, I go around and solder a lot of the seems/edges in the tape in the cavity. It's not necessary to do all of them (with conductive adhesive, it's not really necessary to do any of them) but I get a bunch of them. I do it because I like insurance, and I'd rather do too thorough of a job than one that isn't quite thorough enough. At the end of it all, solder a wire from your shield to the ground lug on your output jack. If it's done correctly, you will pretty much eliminate all extraneous noise, anything that is not a signal coming from your pickup.
This is a photo of a rear route control cavity I shielded using this process:
