Sanyo 31C426 RGB input pinout

[dr.ido]

It's probably analog RGB - From memory the Sanyo MBC550 computer had an analog RGB output.

I've used other monitors that had this connector on an Amiga, though not all monitors using this connector for RGB were analog. If it is a TTL RGB input you'll get a picture with incorrect colors (if it locks at all, from memory the sync is also different).