So today i fired up a Naomi 1 MOBO in my AWSD cab using a Capcom I/O, the game booted up fine up until the 'press start button' screen and then said I/O error and it wasn't picked up in the test menu.
Tried it again in another cab and this time it booted up to the same place, only this time it let me start a game for a bit before the screen went blank and the I/O error screen come up again.
Didn't think i had another USB cable to try, then i remembered my printer one will do, tried it and worked fine, tried the original cable and that worked fine too....i'm baffled...only change is the game yesterday it was Virtua tennis today CAPvsSNK :smt017
Best to use both JVS power plugs on the Naomi 1 mainboard in the Awave.
The Capcom I/O can easily flake out, normally the I/O IC burns out, you defintley need to check your +5V under load to make sure it isn't too high or too low.