The ground lines (black) from the pickups may not be connected to the pickups, they are routed near the pickups. One is probably connected to the bridge.
The ground lines converge at the 1/4" phono jack chassis lead.
The neck pot controls volume and balance. The bridge pot controls bass and treble boost / cut.
Neck pot markings:
(on the circuit board)
BEQ2-BAL (RIGHT)
revB 20150617
(on the pot case)
B504
C504
A504
The pot has 12 pin connectors.
Bridge pot markings:
(on the circuit board)
BEQ3 system - B/T (right)
revC
3EQBBT - CF1 2S 01 20150504
B/T1
VR
(on the pot case)
B103
C103
The pot has 6 pin connectors.
TMB EQ circuit board markings:
BEQ2-BT_MAIN revF 2015-04-10
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You may contact me at kevin@kevinsworkbench.com