You can get a SBO board running on a very simple test rig with a 12vDC supply and a video cable. No modding of the pcb needed. Makes it easier for testing when you're not hanging out the back of a cab.
"My test rig is crude, but for getting the Game logic on the board works fine. The way I read the schematics led me to believe what I'm doing was OK. The LM323 regulators are tolerant to this input voltage and I've had perfect 5.0x DC reading all over the IC's.
Your 12Vdc will need to be beefy, my Jamma Rigs 12Vdc was not man enough to supply enough current to make the board run, I went for an open frame PSU I had spare that was rated at 4amps and worked fine.
The other AC voltages I left off they are for the Audio amplification, I left them alone and tested sound when the game was back in the cab.
See image below of my wiring. "