Ive connected a test button to a Vogatek supergun (version 111) for neogeo mvs use but it dosnt seem to be doing anything when pressed. Is there a specific time i need to press it to get the test screen to appear?
Do you have a 1-slot MVS pcb? The test switch on the Vogatek MkIII is used only on MVS boards with 2 or more slots. You can always wire the test button directly from the jamma connector.
What BIOS does your MVS mobo have installed? If you have a fresh UNI-BIOS, I think you can just hold down your start buttons or something at startup to get to the service menu. Or set one of the hard dips. I've never used my cabs service/test buttons for my 1-slot, so I'm hoping some guess work will still help you out.