Yep I've tried everything, are you saying that the spindle card sends out a pulse not a constant voltage or should I be getting a set voltage, only I'm beginning to think its the LYNX08 unit thats at fault. As I said before I aint got a clue about electronics, do you think the DIYCNC board sends out a voltage or does it send a pulse that get converted in the LYNX08 card. I'm thinking of buying a new SSD513C unit but dont want to spend £110 and still have a problem. Your advice is much appreciated, thanks