Psw 1200 Amp Wiring

soiset

On the psw1200 plate amp, on the circuit board opposite the heat sink, which three prong plug is left unused: the one closer to or farther away from the capacitors? The socket that connects to the plug to which I am referring has three wires: a 22 ga. orange, and two 22 ga. wires within a red insulator, one of which is is in a white insulator, and the other is wrapped around that wire, within the outer red insulator. The socket is white. These wires pass through a square cut hole in the bottom of the circuit board and connect the green pcb.

Thanks