I needed to fix up an old SR-88, but the available schematic was almost illegible. I grabbed the highest resolution copy I could find and tried to touch it up. Some of the lines were very nearly gone, so I had to guess at some of them. There are certainly some mistakes and oversights, but I think it's an improvement.
Interesting to note, is that the schematic very closely follows the board layout as seen from the bottom.
I started to redraw the schematic in eagle, but I quit once I debugged the SR-88. The CD4011 NAND was shot. This seems to be a common problem in these and similar machines.
Anyway, here is the partial redraw and one I rearranged to be more conventional.