EM806s are good drives. Did you order a programming lead, as it makes setting them up easier?


You'll need to study the wiring diagrams to work out what the power board does. I think some of the later Triacs used something similar, and some of the relays are used as interlocks, to ensure critical things weren't solely controlled by the controlled.
The top board is the later controller. Smaller machines used the in built stepper drivers in the lower board. If everything was still connected, you could possibly try powering it up and see what shows up on the 7 segment display. It would give an indication of if there was anything major wrong with the original controller.