Ok, so progress. The switch is a 4-pole, 3-way. Below is a snippet of the preamp circuit diagram with the switch positions marked. The gist appears to be as follows:
The violet wire is a ground wire.
The white pickup wire has a fixed connection to the preamp in addition to going to the switch.
Pole 1 does one thing -- ground the red wire in the (B)ridge pos
Pole 2 is all preamp -- 3 different wires to the preamp connected to a gray wire also going to the preamp.
So there rest of the action is on poles 3-4. Resulting options:
Switch in...
(B)ridge pos
1 - Red pup wire grounded
3 - Yellow preamp wire is grounded
4 - Green pup wire to White pup wire (and white has its cxn to the preamp)
Black pup wire floats
-- This is very close to parallel humbucker. But with the black wire floating, as expected, my bridge coil is cold.
(M)id pos
3 - Black pup wire to Yellow preamp wire
White has its preamp connection
Green pup wire floats (4)
Red pup wire floats
-- This is consistent with the Sterling stock mid setting which would be the rear and dummy coils in series. Neck coil is cold.
(N)eck pos
3 - Red pup wire to Yellow preamp wire
4 - Green pup wire grounded
White has its preamp connection
Black pup wire floats
-- Neck coil hot, bridge coil cold. If the Sterling option would have been coils in series, and white is going to the preamp, presumably that's going to the output jack. And if Green is grounded, then I'd expect red and black to be joined, but black floats.
But I think I've got two options that are going to give some decent settings if, as was my goal, you want more stingray-ey tones:
(1) hard-wire the black pup wire to ground
(B) now you get your full-on parallel humbucker
(M) bridge coil only. By grounding the black wire, the preamp is getting cut out of the mix (assuming the yellow wire was routing part of the signal through some components)
(N) Here you'd have Green and Black grounded, Red and White going out -- so this might be something like an out-of-phase humbucker...
(2) hard-wire Black to Yellow
(B) Yellow is normally grounded, so this just grounds Black, and, again, you get full parallel humbucker
(M) Black would have been tied to Yellow anyway, so this setting is unchanged
(N) Red was tied to Yellow, and now also Black; Green is grounded and White is going out -- so this is kind of a "coils in series" I find the output is notably lower than the full humbucker, but quite possibly usable.
Pretty minimally invasive. I put a switch in there to let me flip back and forth between the two for a while and see if one or the other ends up being more usable.
If anyone figures out better patch points on that preamp, I'd probably be unable to resist more experimenting...
Cheers!
View attachment 911303
