nothing, there is the 2 inputs and that is it. i tested them, and i dont know if this helps solve anything, it looks like 33 volts ac to 1 wire, and nothing to the other, then when main board calls, it switches 33 volts to other input, and nothing on other.. does that mean that only 1 of the eye sensors has power at a time? just throwing it out there.
I never before read schematics, so please correct me on anything i have wrong.
looks like ac comes in, the bridge rectifier, sends dc voltage to motor positive, and thats is it from the diode diagram. so ac voltage continues to OP1 sensor. (no power to OP2). Then if it makes a connection, sends the ac voltage, on down to the 4093(which is really just relaying a sighnal whether it comes from OP1 or OP2). [i dont know is the 4093 would flip voltage from ac to dc]..which then goes to the tip120. ac voltage activating the relay, (emitter ground) sending the ground to the negative of the motor.
moves until the light sensor on OP1 had a hole, loses connection. then main board switches IN to 2nd wire, rectifier does same thing, everything else same, but it moves motor until OP2 has a hole in disc, and loses connection. this would leave the motor with no power in off cycles. and allow the main board to know which position it is, by whether IN1 of IN2 has power to it.