Digging up this old thread. I was about to start one with the same topic but found this. It hasn't quite answered my questions. Apologies if this is not appropriate. I will start another thread if directed to.

I have a switching power supply with +5V and +12V outputs. Coupled with the Siegecraft and Pinitech testers I have successfully bench tested some Data East v2, v3 and Williams System 11B boards. These boards work easily due to the external power supply.

The WPC power driver board is a little different and my electronics knowledge is not solid (I was trained in a completely different field with a career in yet another completely different field). I looked through the schematics and I think it's safe to do what I want but I would like to have some confirmation from smarter people with more knowledge and experience than me.

1) I think it's safe to plug +5V, +12V and GND to J114 because I've seen switching power supplies with +5V soldered to the test points for failing +5V circuitry.

1a) Is this safe to do?
1b) For +5V will it cause any damage to the LM323 or other components upstream?
1c) For +12V will it cause any damage to the LM7812 or other components upstream?
1d) If so can I simply pop out F115 to protect those +12V components?

2) If I attach +12V to the +18V test point to supply power to the lamp matrix will this cause issues with the LM7812 or other components upstream?

Yes. I have connections for the CPU board, power driver board, flipper control board, dot matrix controller board and dot matrix display. The dot matrix display is low voltage (completely driven off +5V).

The only thing I haven't figured out is how to connect the sound boards (both pre-DCS and DCS) to the setup. It's the different AC inputs, rectification and negative voltages for the amplifiers that currently have me stumped (as mentioned my electronics knowledge is limited but I do know enough to know that "BadThings(tm)" can happen very quickly if you're not careful or correct).

Thank you for the confirmation!

I wouldn't call a tabletop a test fixture ... more a backwoods hillbilly approach. Pretty much wiring harnesses and the ribbon cables. I've had to fix a few (of my own) boards now and my machines are (currently) not located where the repair work is done so each testing of a repair requires a trip and that slows down the turnaround time. I'm just trying to increase my level of confidence of a repair. It will also serve well in the future as I have a line of project machines waiting.

I'm happy to test high voltage and AC at the machine for three reasons.

1) Having a transformer would greatly complicate the wiring on the tabletop.
2) I am trying to avoid high voltage on the tabletop.
3) Transformers are f***ing heavy.