Hi Benja

I spoke with my learned friend AngelTech (from the Denford data forum) last night and showed him the possible replacement board. He had this to say: "first off, no that board is no good for an unisolated spindle drive like you have. There is no dc isolation on the board. It would be ok for an isolated spindle drive or an inverter."
So my new plan is to swap my brand new Sprint 1200 for the 1220i (fully isolated driver) and see if that works. I also spoke with Rob Rossini on the phone ( who was very helpful) who said he may be making some more V5 (the diycnc upgrade to the V4 boards) at some point soon.