Help getting an unresponsive MV4 board running...

I have an MV4 board that I would like to get running, but at the moment I'm getting nothing from it. As I don't have a proper Supergun, I connected it using the board from a Chinese consolized MVS (which works fine with another 1 slot board I have, at least for power and video).

I've done a decent bit of tinkering with other MVS and AES bords, but have never touched an MV4 before, so was wondering what steps I should take to try and get it working? Only things I've checked so far are that with the top board removed, the voltage regulator on the power amp section of the board is outputting 5V and the BIOS voltage is 2.5-2.6V. The boards are a little dusty, but I can't see any signs of corrosion of broken traces at the moment.

Edit: Does the MV4 make use of the -5V line on the JAMMA pinout? The pin is populated, unlike other MVS boards, but I don't know if it's internally connected.

You should have a steady 5V going everywhere except to the audio power amp.
It comes straight from the JAMMA connector so you might have a weak/defective PSU or a short on your MV4.

MVS boards don't need -5V.

I doubt the power from that consolized unit is enough to power a 4 slot especially since he's using a 7805 or similar circuit to convert the 12v to 5v so it would be limited to 1.5A and some 4 slots use more than 5A.

Thanks, I've ordered a Supergun and will give it another shot once it arrives and I get hold of a PSU.

If I do get it working and decide to consolize it with a 5V mod, what minimum amperage AC adapter would you recommend?

So I got a proper Supergun running, but unfortunately am having some issues with it. As you can see in the video, the diagnostic BIOS showed no issues, but I'm having what I believe are sync issues. I've tested the Supergun with an MV-1FZ and had zero problems. I've checked continuity on the sync line from pin P on the JAMMA connector to the 100 and 470 ohm resistors, which both appear to be fine as well, but am having trouble working out where the line goes to from there without having to remove the BIOS socket. Any pointers? Is it even necessarily a sync issue?

https://www.youtube.com/watch?v=SGrVEgwsH4Y&feature=youtu.be