Quoted from Alienagent

I tried fixing it - (Monopoly)
I repaired the original power supply and it now runs without the additional power supply that was in there.
That didn't fix it-
I think it has 12v problems.
Tim

That was where I last left it too. (I also replaced caps in the original supply and tried the old 12 volt section, and then reversed it when there was no apparent difference.) Basically the board has to sense an unregulated +12volts before it will complete it's power on sequence.  That being said, it did at some times, sometimes without failure, and then with a number of failures, and back to working again, which made troubleshooting it difficult.  The power supplies appeared to be outputting the correct 12volts, but I suspected the traces or connectors were compromised in a place that I couldn't trace out (and eventually I was forced to give it up to make room before I could source the problem).  Went to a lot of trouble getting an additional MPU to test (similar problems), which would lead one to believe it wasn't the MPU traces (but as I recall there was something else inconclusive about that MPU swap as well), schematics, etc.