I obtained several of these boards when I got the initial multibus boards. They came with no manuals.
This is a multilayer PC board which makes it much more difficult to trace the wiring and generate a schematic. I have this partially complete. I ignored all the RS-522/449 wiring and only captured the RS-232 interface. The hand drawn schematic is here.
This board has a Z8530 or i82530 SCC chip.
1546 MST 20 February 2012