The Q30 is multiplexed between the left eject hole and the left flashers. You said the flashers are the only thing not working. To be certain, run the solenoid test and test the left eject hole. If you have proven the flashers work by grounding out Q30, and everything else works - then the A/C relay is fine, and as you have already discovered the entire circuit paths after Q30 would also be ok. I think you will find the left eject hole also doesn't work.

Then your problem would be something upstream from Q30. Your best bet would be to stop shotgun guessing and troubleshoot with a DMM, logic probe or scope and check for the pulses at the points in the logic diagram to see where the signal is lost.

s11ssol2 (resized).png

Both the coil and the flasher use the same circuits on the CPU board, so if the eject hole works then the flasher will work. Now since it doesn't work during a game you need to look at the switch input that tells the CPU to turn on the flasher. This would be switch #40. It can be out of adjustment, have a bad diode or a broken wire.

pinbot (resized).PNG

pinb (resized).PNG

Guys, don't forget the number of flasher resistor boards under the playfield on PinBot and other Williams of the era. Those big white wirewound ceramic resistors are notorious for breaking off their wire leads, cold solder joints, and just falling off completely. Even if they look like they're installed and solid, many times the lead is snapped inside the resistor and can just be slid out completely becuase its no longer internally attached.
I'd be looking at those before digging into any board-level repair.

He has already explained that the lamps work when manually grounded, so the current limiting and preheater ceramic resistors are not the problem in this case.

Fair enough, guess I didn't read that portion completely.

Do you at least have continuity from the relay board to the lamp ground wire? Sure, the relay itself may be working but cold solder or something could be preventing it from activating the flasher. Or at least give a place to check continuity from and isolate the breakage. You can always ground the diode on the relay to keep it pulled in then run the eject coil test and it should attempt to flash the bulb since the relay is engaged, correct? If you still don't get a result, then there's a wire breakage between the relay board and the lamp socket.

If you are referring to attract mode, no they don't work then only during a game.