I believe if you put a momentary low (ground) on the blanking line this will initiate a system reset.

Edit: the same thing can be accomplished by driving the output of the 5V threshold detector on the CPU board low to simulate a 5V undervoltage fault. This is likely better as you force the ASIC to generate the blanking pulse.

Going through your test/audit menu you can reset a game that way. Any one game in particular?

That's a good question I took "any way to reset a SS game?" literally as how to wire a reset switch into a Bally Scared Stiff machine ...

Looking at the OPs two listed games, RBION ia a Stern Whitestar game; this board set already has a reset button on the CPU/Sound board which makes it easy ... the other game is a Williams system 11 and I cant help you there, the OP may be better off posting in the early Solid State forum for answers.

I did not want to assume it was a game he has.

OP, But reset for what reason? Just trying to restart a 1 player game when a 4 player game is in process?

You could hit the slam switch on the coin door. I used to that all the time on Black Knight when I was having a bad game.... knee the coin door. I've since learned to play better so I don't do that anymore.

You could wire up the coin return to the slam and hit that.... how often do you need/want to do this? If it's just occasionally, opening the door and hitting the slam isn't too bad. If the game is frozen up and needing a hard reset this won't work, though.

You won't wear anything out by using the power switch if that's what you're worried about - in fact on some games (bally/stern early SS) you might find an issue with the mpu board where one of the reset transistors (q1 q2 or q5) need to be replaced (symptom: boots fine when cold, if you power off for about 5 seconds and on, solid led until you let it sit for a while).

I suppose you could wire a switch that just cuts the power to the mpu.

That would tend to reset the game without having to turn the other power switch off and on. But that is pretty much a reboot anyway.

It's not only little darlings that do that. I've had adults visit that do the same thing. Either make the slams really sensitive or wire a switch up to them hidden in the coin return you can press. Any auto plunger games that can be set to auto plunge after 30 seconds might be a good idea too.