Is that in the Mach set up as I haven't changed anything on the machine or the wiring going in, I just changed computers. When I look at the diagnostics page all seems correct, there is a green light on the forth pin along on the interface diagram but I'm sure I had that on the old setup. Last time I had this was on the initial set up of my machine in 2009, I had an interference voltage on the 10v supply that controls the spindle speed. I shielded the wires and redirected them which seems to have solved the problem, but its back. Any other suggestions and where are the relay switches? Jim