Right a new thread on this
Taking advice from here , I am about to start building a board to make this work.

I intend to remove Boxford's boards but retain the Lenze controller. Anyone wanting to have a play with these boards shout now!

What is the function of the optoisolator and do I need to retain it ?

Then the transformer has tappings at 20v with rectifier ,
Other tappings at 9v (x2) , and 12v seem to have their rectifiers external, on the the processor board .
Am I better to do away with this and fit distinct PSUs for each required voltage ?, or retain this and rectify the outputs

I am trying to fathom the circuit of the relays , with their forward , reverse, and latching functions for spindle control . These have been working so hope to retain them, Will spend some time getting head around their function

All suggestions welcome