Week of Sept. 6: Jammified the power supply by adding a castoff ATX computer power supply. Misled by Arch Rivals' description at KLOV: "The original game kit comes with a JAMMA adaptor, but the wiring on that adaptor is not strictly JAMMA," this machine had no JAMMA adaptor; all connections were board-to-wire. But I've seen an Arch Rivals JAMMA board for sale recently (by Paige O.), so I believe this game existed in multiple versions. Probably there existed a jamma conversion version which differed from a dedicated cabinet.
Ultimately this will be a MAME-based multigame so I'm not sure there's any point in adding a JAMMA harness. I seem to be doing it for my own amusement, and for future flexibility. Nevertheless, the PSU in Arch Rivals is not so Jamma standard. The switch mode PSU provides only +5v (fer real - same size as a standard arcade switcher - just 1 voltage!) It also has a linear bipolar 12v source is provided from a 12v tap on the main power transformer which connects to a standalone PSU board with DC rectification and a giant smoothing cap. +/- approximately 14v is then jumped to the audio board which has voltage regulator ICs for +/- 12 v. This appears to only power the audio circuitry and audio power amp.
Anyway, the Jamma standard wants +12v, +5v, and -5v. Rather than keep the audio board in use just for the regulated +12v, it seems simplest to just use a switch mode PSU for everything. So I ripped out the 2 power boards, and the PSU box and put in a single ATX PSU. It pains a little since computer PSUs have notoriously short longevity. I want ---steaming pile of meadow muffin--- to last for 50 years without maintenance. But whatever, as I become more handy with repairs that matters to me less and less.
I'm using a J-PAC solely to protect the CRT from VGA. But I'll wire the player one and player two controls with a connector, again for future flexibility. I may be insane. It only becomes apparent to me when I type it all out.