Ok this is my other problem I posted at the end of my other thread. Machine is a Kiwa Excel center-4 from 1984. Control is a Fanuc 3m model c. I was having trouble with a watchdog alarm that started all this. Tried a replacement motherboard which ended up throwing a z axis feedback cable is disconnected error. I then took off the z axis servo motor cleaned it with QD electronic cleaner and reassembled. After the cleaning and reassembIing the motor the z wanted to slam into the table. I then checked the signals from the encoder with a scope. Found the encoder had 2 separate square waves when rotated by hand also it had one single pulse per rev on another wire. I checked the same signals at the board. They were the same. I determined by this the signal wasn't getting into the board hence the error it had on the screen. I then bought another motherboard and that's where I'm at now. I hooked up the new board and entered all the parameters and got the control to come up with no errors. When I release the estop and hit the reset button the z axis tries to rapid into the table. When it does this the 2x4 I have holding the head up stops it and the drive throws an ocv error. If the encoder is putting out signals when rotated that means it is working right? What would cause the z axis to take off in the negative direction as soon as the servos are powered up? I also tried another velocity control unit for the z axis with no change. What do I check next? Is my encoder bad even though it puts out signals when rotated? Dan.