I've been recruited by the Neo Geo league to defend fun against much boredom

[celerystalker]

That's incorrect, 10 and L are ground and hot for mono sound on a JAMMA board. On a MVS system they're both hots for left and right speaker, so if you slap a JAMMA board in you're crossing hot with hot.

Pin 11 is the hot for one speaker mono audio on MVS, but on JAMMA it's a preout audio hotwire that isn't amplified.

The audio wiring and the test button issue are the sole reason people buy MVS-to-JAMMA fingerboards. Single slot MVS boards do not have these issues though, they're JAMMA compliant.

There is standard JAMMA pinout, photographed directly from the manual for Time Soldiers. That's where I'm getting my info. If there's something else I'm missing, I apologize. I run a one slot at home, so Az may know more than me on this. I'm just comparing a PDF of the MV2-F manual with my regular JAMMA manuals. Plugging a non-stereo JAMMA board into an MVS-2 or 4 harness should result simply is audio only coming from the right speaker in mono. It would be plugging the MVS-2 into an old JAMMA harness that would cause the hot/hot on a mono-wired harness.