MV1A PALs
The MV1A MVS boards have two [PAL] PAL20V8H-15 chips which are used to provide some of NEO-C1's functions. If any of them fails, the board certainly won't start up.
They can be replaced with new or working chips programmed with the following JEDEC files:
SNK1A
Does address decoding.
JEDEC file: File:SNK1A.zip
SNK1B
Generates the DTACK signal.
The CN2* inputs are probably connected to the cartridge ROM speed configuration pins (ROMWAIT, PWAIT...)
JEDEC file: File:SNK1B.zip