Hey thanks I did check the fuse! Sorry all for the long haitus. So I worked on it for a few weeks and started testing every resistor, every transisitor, almost got all the way through them and then I read a post on here from someone with the same board and same problem. They sent it to
https://arcademonitorrepair.com/ and got it fixed so I decided I'd try that since I had to focus on work this summer.
Super nice group, but when they got my boards they didn't really look at them too hard. I sent the one I was working on plus the parts board I got with the machine to see if they could get both working. They saw my boards and saw they weren't stock and said they weren't going to try to fix them because it would take a while and I had paid extra to jump to the front of the line so they figured I wanted a response fast. They did say, however, they had the exact same board in stock and working which blew me away so I said sure send me a working board!
I got that one home and it does in fact work. I got it all tuned up and dialed in. The board they sent me has a number of components repaired and I think I need to replace the same components on my non-working board. I ordered all the parts but I've gotten caught up in work so I haven't tried to repair it. Plus I've been enjoying playing my machine haha.
I've got a hypothesis as to what's going on. So I've got a Pandora's box JAMMA edition and I've got a Japanese Vampire Savior CPS2 A/B board and I swap between those two. I bought a 2 way Jamma switcher that swaps between the two boards when I hold P1 and P2 start. The Jamma switcher doesn't work when the Pandora's box is the 2nd board. It swaps from the CPS2 to the Pandora's box, then flips back immediately. When I make the Pandora's Box the 1st board on the Jamma switcher it will power up.
Furthermore, when I take the 2 way switcher out and just hook up the Pandora's box there's this ticking/staticky/electricity shorting sound when the Pandora's box is starting up before it's feeding out video signal. Reading some posts while trying to repair some people have said that fast ticking is a power supply turning on and off, whereas if it was a long wait then a tick over it would be a blown HOT.
The previous owner also had a pandora's box JAMMA edition installed. I think what's happening is that the Pandora's box is feeding nonsense to the chassis board video while it waits to boot and this is burning out something on the board. Probably the power supply is my guess. I did a quick search through google to see if anyone else has experienced this but no easy hits.
Anyway eventually I'm going to replace the power supply components and test my theory. Thanks everyone for your help I'll update the post if I know more!