Ok just to prove Im dumber than I look, I've spent the last 3 hours in the shed looking over this board again. Im trying to send myself insane working on a system1 board

I've got the board working again - but only when I run it from a PC power supply, It doesn't boot when using the Gottlieb power supply. Interestingly if I use the PC power supply for +5V and -12V and the gottlieb power supply for 42, 60v the machine boots fine (im making sure I have a common ground between the two power supplies).

TO make things even stranger, the PC power supply is only outputting about -11VDC, not 12V DC...

This is very strange as the Niwumpf board plays fine.

This has me wondering if I have either
1) problem with -12v rail on gottlieb power supply (Niwumpf doesn't use it)
2) enough mains noise to effect the System1 board, but not the Niwumpf
3) potentially have a startup issue with the system 1 with the games power supply not being stable when the reset goes high.

The mains noise on the Gottlieb supply is in the order of 0.05V on both 5V & -12V rail (measured with CRO). Bloody stuff all.

Im scratching my head now, can't let this go... Thinking I might throw some electrolytic caps at the Gottlieb supply.

Guess the good point is the System1 board is up and running again (well with a PC supply).

Anybody seen weird stuff like this before? Any advice...

Time to turn off the brain and go to sleep