*****SOLVED - SEE BELOW

This was a project SoF. Some issues have been repaired, but I'm still finding non-serious hacky/sloppy things.

The only non-stock board is the AUX power board. It is the older revision with the single F2 fuse (not F2a/F2c). But there is a possibility it was original, as the game has Proto EPROMs and is a very low production number. No Red boards though.

Here is what happens on Power on:

*MPU Boots into attract mode.

*During Solenoid test, Q25 transistor pops quickly (not lock on), takes out the Pre-Driver 4401 and even the gate on the 7408!!! F4 Blows shortly afterward. I believe it occurs right away at the 2C coil test, but the 4 times it has popped, I get too startled to read the displays and make note. The traces are getting too delicate to keep replacing, so I need to solve it for good before the next power on. It makes my basement smell awesome :\

*Flash Bulbs on the ORN wire side blow out their filaments (01C, 02C, 03C, 04C, 05C, 08C).

Possible Issues:

1. 50v YEL-VIO is leaking to the ORG 25v "C" side - Problem with this hypothesis is that the AUX relay tests out fine, and D39-42 test out fine, as do D31-46 on the AUX board.

2. I wired a coil/flasher wrong somewhere - I did strip the PF to CC it, but I've quintuple checked my wiring, and it all looks good and matches my photos and schematics. The only hairy area is that GI relay on the underside of the PF. The schematic leaves out the wiring on that, but it appears it just gets daisy chained 25v power from the top center flasher and controlled by the brn-red gnd wire engaging. Nothing fancy there.

3. I have continuity between the RED 25v Controlled Solenoid line and the ORN "C" side 25V Switch Solenoid line - This is with flash bulbs installed though, so that makes sense right? The job of the diodes on the AUX board is to block the interaction between the ORN/BRN and ORN/YEL-VIO.

That was a lot. Hopefully someone has some insight for me (Thanking Grumpy in advance).

SOLVED. I'm dumb and had interconnect board flasher connections wrong on it. J4 was swapped with J11 on that board. They aren't keyed the same either, I just had them upside down, they're keyed the same inverted. It is hard to believe I made such a silly mistake, but I probably rushed those connections and forgot about them.

Also found a hack on the back box that was connecting both strands of GI to the same terminal on the GI relay. Now I just gotta put it back together and tidy up the wire mess I made.

So, yes, the ORG and RED power lines SHOULD NOT have continuity anywhere, for anyone reading this in the future.

Lesson learned - Check the stuff you normally don't look at.