Have you checked out David Gersic's website? He's THE zaccaria guy. You're more skilled at this stuff than I am but he describes the reset circuit and power failure circuits at the below link which might help.

http://www.zaccaria-pinball.com/gen2/powersupply.html#PowerFail

Here's an old RGP post where david talks about things in more detail. Perhaps this will help.

https://groups.google.com/forum/#!topic/rec.games.pinball/oOPVe6ko3mw

There's also this but I can't find a source for getting David's version of the test rom. I'll contact him as I'm going to need it in the near future myself anyway.

http://www.pinrepair.com/zac/manuals/zac_gen2cpu_testdoc.pdf

Glad that I could help. Whenever you get to updating your universal display let me know if I can help. I've got one of the first ones you developed. Sticker on the box says v1.0 code. I didn't realize when I ordered it that you only supported Williams games so far. Out of all the games my brother and I own we only have 1 digit display williams. We have a whole slew of Zaccaria gen2 games, a couple stern's and some bally's though.

Not sure I have a way to reprogram the board (I assume the unpopulated header on the right side is a programming header?). Let me know what I might need for that. If it's not too expensive I'm open to getting whatever it is I need.

I don't currently have access to a board to look at unfortunately but looking at the data sheet says "Run/Wait - Informs external circuits as to the run/wait status of the 2650 processor". This would likely not be used right?

Here's the part on Run/Wait. TLDR it should be high while the processor is running instructions.

In case you missed it there's a section on david's page for datasheets for everything.
http://www.zaccaria-pinball.com/gen2/datasheets/index.html

Unfortunately for some reason he said he's not releasing his test rom so we're stuck with the Leon one for now it seems.

run_wait (resized).png

Oh i forgot to ask. What oscilloscope did you get? I'll probably be getting something to replace the dinosaur i currently use. (It's a tektronics 468 or something. Super old).

I'm considering getting the Rigol DS1054Z in the future. It's 50mhz but you can software mod it to enable 100mhz. Not that I need that for pinball stuff probably. Mostly because it has 4 channels and there have been a couple times where I wish I could watch 3 things.

does yours use BC548's? that's what TR3 is so should probably use those in place of the 3081.

That is an awful lot of bad chips

Did you get the flippers sorted out? There are 2 fuses on the bottom of the playfield for the flippers (maybe 1 for flippers and 1 for something else? i can't remember). But there's also a relay under there for the flippers. Hopefully the relay is still good.

Unfortunately my devil riders is currently folded up. I may set it up here in the near future and if I do I'll take a look at things.