Simply grounding the pin won't trigger a switch closure. You need to short the two pins together to allow the signal generated by the MPU to return to the MPU and be read as a switch closure. From what I see shorting pin J3-1 to J2-7 should trigger a self-test switch closure.
I am not 100% sure on this, but I think the button on the MPU at S33 only clears audits. I would suspect a bad connector on the MPU this goes to the coin door. So, the wiring to the coin door, the coin door switch, or a bad pin, loose fit, or other connectivity problem would be my first course of action.
> Simply grounding the pin won't trigger a switch closure. You need to
> short the two pins together to allow the signal generated by the MPU
> to return to the MPU and be read as a switch closure. From what I see
> shorting pin J3-1 to J2-7 should trigger a self-test switch closure.
> Bill Stahly
Bill has the right idea here. Though A4J2-7 is marked as not used in the manual.
My guess is that you'd need to short A4J3-1 to either A4J3-2 or A4J3-3, but that's a bit of a WAG.
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Install any Bally system 1 MPU in your game, once it powers up, see if
you can enter test mode via the coin door test button. You will
immediately isolate whether it is the board or cabinet wiring. Borrow
a board from someone or take yours to somebody with a Bally SS pin
aind install yours in their cabinet. If you can get into test mode,
you now know your board is good an the problem is in your game's
This is a very simple circuit. U10 pin 40 ---> 100 ohm resistor ---> J3, pin 1 ---> Self-Test switch ---> Solenoid Driver Board J2, pin 7 (dedicated ground). This circuit on the MPU is in the corrosion zone so even after changing the socket you must ring out all of the traces and may additionally need to replace connectors at the harness.
Get your multimeter, set it to the 200 ohm/continuity scale. Put one probe on top of U10, pin 40 right at the IC. Put the other probe at J3, pin 1. You should read about 110 ohms. If not then check the solder pad to the pin. If you now get continuity you need to double-check your soldering to the socket for U10. The other side of the self-test switch grounds out on the solenoid driver board: J2, pin 7, self-test dedicated ground return. This is a simple ground, not a strobed line as others have said. All of the headers here are candidates for potential broken solder joints.