V3 looks to be the sound CPU, I swapped it out with a known working Hitachi 6809 (from a working Namco System 1 board) and still the same issue. Likewise, the sound CPU in the other working board works fine.
Not too sure at this point where to go.
I saw this over on shmup today - marqs has modified his firmware to work on a NeoGeo MVS board (Mv1c board in this case) - he said its the easiest and will be updating his public github soon with the code and instructions...
According to this post - its the chip at U3.
I will try replacing this and see if it works.
I have a PacMania board that boots up fine, has music - but some sounds are missing. I assume at least when you eat dots there should be sound :)
Anyone have an idea of where I can start troubleshooting? Perhaps start by reburning the 2 sound EEPROMS?
Actually - I just figured it out - darn Flux! even though my multimeter didn't show continuity between the DAO pad and GND - there must have been, because I cleaned it up and now all works as expected!
Now I am ready for the Multi!