Super gun problem, powersupply fan doesn't even come on

I recently attempted to build a supergun. I followed the stuff on Engadget, and used one of the JROK video adapters. I’m pretty sure everything got wired correctly. However, when I turn on the device, the thing pops on, then pops off. The ATX power supply fan does not even turn on. If I unplug the Jamma connector from the 3s or NEO GEO board though, it turns on just fine, and runs. Anyone have any idea what might be causing this? Might i have a short somewhere?

Check your wiring again, especially the grounds. What kind of power switch are you using? Also, don’t use the 3S board to test your supergun, it’s worth too much money and those boards are very sensitive.

That sounds exactly like a short somewhere. Check all your screws and where everything is touching. I’ve had screws in to tight cause boards to short on me before.