Strat/Seymour Duncan Pickup Replacement: Those mysterious inner wires.

Here's one for the pickup replacements folks, and it'll hopefully save somebody some anguish: after I put a Seymour Duncan Hot Rails in the bridge position of my strat, which was fairly easy, I decided to finish the job, and got a Vintage Rails for the middle, and a Cool Rails for the neck. Versatility, all that. I followed the wiring diagrams provided, it wasn't that hard...BUT....

There are two more wires in the strat, in the body, itself, that no Seymour Duncan schematic addressed, and I looked hard. The two wires to the jack are documented; but, evidently, there can be two more wires in a given strat. One is a black wire seemingly coming from nowhere in the body (not the jack), the other is just screwed onto the inside body itself (the wire is held by a "ring" that you just screw onto the wood.

Fender evidently has gotten greedy with schematics; they don't share these things anymore as I understand it, you have to buy their wiring book. I refused, and just kept looking and looking, and guessing. So....the black wire that runs into the body had to be a ground (because it's black). But soldering it to the volume pot as a ground breaks the tone knobs. It turns out, and I don't know the logic, that this must be soldered onto the center pot (the middle knob, a tone knob). The other black wire, that screws onto the body, must be soldered onto the volume pot like any other ground wire.

More research showed; the first black wire that runs mysteriously into the body, is actually grounded to the base of the tremolo; this is the one that gets soldered to the middle (tone) pot. The second black wire has to do with the "paint shielding", and requires a ground to be attached to the body to "ground the paint" as it was explained to me. It has to do with a particular kind of paint used on the inside of the guitar. I don't fully understand this but that's the best explanation I got.

Also, the way Fender wired my guitar stock, did not match any of the schematics I could find anywhere. The way the pots were wired to the switch was different than their schematics. So in the end, I just removed every single wire from the guitar and started from scratch, followed the Seymour Duncan schematic, finished the job with the two "mystery wires" the way I had figured out, and lo and behold, a working strat now graces my arsenal again. Sheesh!

Home electronics, what fun.