Just been messing about again and noticed that there is an LED on the BOB, this is on normally, but after running the axes up and down manually a bit, the LED flashed off then on and Mach threw the "e-stop requested" error, after that the torch relay will not trigger and the axes start messing about.

I really can't believe I've fried a BOB or the PC surely?

If that is the case then there is little hope of success as I have done almost everything I can to shield this stuff, I have not driven a ground rod yet as its in the factory at work and i doubt the landlord would appreciate that :)

I could understand it if I hadn't connected the plasma ground lead or something else stupid but I even checked it with a meter to the work-piece first!

I will need to order a parallel cable as they are not standard ones and have two DB connectors whereas a parallel lead has a centronics on one end, got boxes full of them :(

I will disconnect the motor drives and watch that LED for a test. I'll also ring cnc4you and see exactly what that LED indicates.

I might be able to pinch another PC but even if that works, I wouldn't risk another test without discovering the point of destruction.