A good start is to check out the manual and see what you’re missing in regards to the boards.
https://www.arcade-museum.com/manuals-videogames/S/sinistar-inst-manual.pdf
You’ll also need to determine what connectors you need, as I notice there’s wires directly soldered to connector headers. The manual should tell you what connector wires are for power, video, audio, controls, etc.
Next, determine how you’d like to power this thing.
You could try to find a working original Williams linear PSU, but there are switching power supplies available.
You’ll need to also decide on the monitor. I’d you go with an arcade monitor (and can find one) that’s be the easiest to connect to. If you decide you want an LCD, you’ll have to also get an upscaler to convert the low res SD signal to display on an LCD.
There’s a lot of things you’ll need to buy just to determine if the board even works. I wouldn’t even think about a cabinet project till you can find out what’s wrong with this board.
Thanks for that info. It's similar to a document I had found, but with higher quality.
https://www.arcade-museum.com/manuals-videogames/S/Sinistar.pdf << the one I found does have the schematic for the CPU/Rom/Sound/Voice boards however, but doesn't have the IO board or linear supply schematic.
The soldered harness has a button to press to insert a coin, the 3-button diagnostics panel for the coin door both soldered to it, the joystick cable is soldered straight to the IO board as well. The audio wires are connected to the speaker on the back of the backplane. I think that's all covered, so the only things I would need to identify are which wires go to the monitor and to the power supply. I think the guy I bought this from actually had this hooked up on his bench and played it while he was between working on other games. I kind of lost contact with him 20 years ago though, and I don't have any of my email from that time. IIRC, he had to take the original harness off and reuse it on another game he repaired. Once I know it works, I can probably construct a new one with some molex-branded connectors if I really want to keep it.
Also found this on troubleshooting it.
https://mikesarcade.com/cgi-bin/spies.cgi?action=url&type=info&page=Williams-hardware.txt According to this, it appears that I have all of the original boards for this aside from the linear power supply. (CPU, Rom, IO, Sound, and voice rom.) It's a stand-up board set, rather than a cockpit one, so no extra sound board for stereo.
I've found upscaler/rgbhv converters, the main concern is that they seem to say only 30-32khz horizontal for rgbhv, and I had seen somewhere that this might be a 15khz game. This was $20 off ebay. I have some 1280x1024 4:3 LCD monitors I can use, with both DVI and VGA connectors, if I can find an adapter board. One idea I have for this once I build a cabinet is to make it switchable between the Sinistar, and a Mame cab. One of those monitors would probably let me do that with the DVI plug to mame, and vga to the sinistar adapter board, then some sort of rig to rotate the monitor for horizontal games. This is definitely not going to pretend to be an original cabinet. I might make it as a 3-player with the middle position being the 49-way joystick for sinistar, and the other two for mame. Or at least that was my plan for it when I first got it.
Also found a power supply that was designed for williams arcade boards for $39
http://www.arcadeshop.com/i/892/williams-power-supply-conversion-kit.htmI found a set of ram chips for $35, but it sounds like I probably want to swap for 4164 chips instead if what I'm reading on other threads is correct, if I need to replace the ram. (And get the necessary parts to modify it for the different power levels of the 4164 chips.) It just so happens I have a stock of MN4164P-15A chips from when I was repairing my Atari 130XE, so that may be an option. It looks like the chips on the board now are 250ns, so 150ns chips should be fast enough. Is this adapter all that's needed for that mod?
http://www.arcadeshop.com/i/894/williams-4116-to-4164-power-adapter.htmI've a reasonable amount of experience on electronics work, but I'm lousy at desoldering parts. I think if I have to replace any sockets I'd probably send that off to be repaired instead.