So I finally got some time to continue working on this. I've been reversing the main controller board with the Z80 Processor. I'll do a better write up once I get all of the digital logic sorted out, but this is what I've got so far. I've got all of the connections made on the board, the only thing that's left is to layout the schematic better so it makes sense. Basically my methodology for reversing these boards tends to use a lot of nets and parts are just scattered all over since I don't know the design intent, and I have to go through each sub-circuit, determine the design intent and functionality, then lay the sub-circuit out in a more appealing way. You can see an example of this in one of the original schematics I had for the motor signal condition board, and the final layout (original, final).