Second post on this issue long story short....

- Son tried to replicate me measuring test points, "got a big spark" near the 20v TP and the 5v/12v regulated TPs, so two shorts.

- I'm guessing this explains why my MPU board mysteriously died (bought a rottendog MPUSEC replacement) and why the new board is causing this - https://imgur.com/a/y72iB5u (1st pic is with ribbon connected to all boards, 2nd pic ribbon is only connected to DMD board. Isolating the other two does nothing). All lights and logic seem to work, can play a game without sound or DMD (see pics).

- Driver board was recently overhauled and all test points are good. I thought the driver board was the issue, 12 digital was a bit low, now all voltages are rock solid.

- Ribbon cable is new, it is properly seated, I have tried re-seating it many many times, I have examined the headers on all boards, using the old/new ribbon cable results in the same thing.

- Need to know if these shorts messed up all my IC chips? ram chips? all chips? on all boards? or specifically what is most vulnerable? My logic probe skills are minimal at best but getting there.

- The old MPU board will not boot. u22 chip (security), u14 and u24 all seem suspect not getting ANY activity besides oscillator using the probe on any of the buses and u24 gets ridiculously hot. d19 and d20 stuck on d20 off, won't boot. New rottendog board seems functional (it boots and plays) but I don't have another WPC-S to test it in.

I have been working at this all week, learned so much already but I'm really starting to get frustrated and this admission from the boy is not helping.

Update: MPU fixed, DMD board fixed by replacing the RAM, trying to diagnose the DCS sound board now...https://pinside.com/pinball/forum/topic/jack-bot-wpc-s-dcs-sound-board-issues-