The SGB-MPF-I board is one of the less well documented extensions for the MPF-I and MPF-IP eco system. This project could help finding more information and making it available online.
Available are some photo's (component side only), the ROM dump (from MAME) and a review of the board.
The board is based on the very well known G.I. AY-3-8910 sound generator chip. Based on the schematic, the circuit is simpler than other known implementations.
The main lacking item is the manual, which should provide a better schematic and a description of the ROM routines. From the review we know it can do a piano and some sound effects (Gun shot, Exploding bomb, and Storm).