[reabdet21]

I have a fault that I have not seen before. If first happened during a milling program. The z axis began running away downward. It ruined the part and faulted. I rebooted again and the z axis slammed home and the other two axis were normal for the homing. commanding the z axis would then cause a runaway for a couple of inches and then a dac overflow fault. I shut it off and left it off for a while. I booted normally but soon faulted again with a dac overflow. It always boots normally after I leave it unpowered for a while but soon faults. For that reason, I don't think this to be a sensor problem. Any thoughts would be appreciated. When it faults, the z axis moves at a high rate of speed. The mill is a 1998 with the enclosed computer and 2 cannon plugs on the z drive motor.

[mactec54]

I have a fault that I have not seen before. If first happened during a milling program. The z axis began running away downward. It ruined the part and faulted. I rebooted again and the z axis slammed home and the other two axis were normal for the homing. commanding the z axis would then cause a runaway for a couple of inches and then a dac overflow fault. I shut it off and left it off for a while. I booted normally but soon faulted again with a dac overflow. It always boots normally after I leave it unpowered for a while but soon faults. For that reason, I don't think this to be a sensor problem. Any thoughts would be appreciated. When it faults, the z axis moves at a high rate of speed. The mill is a 1998 with the enclosed computer and 2 cannon plugs on the z drive motor.

Encoder or Cable is damaged check the cable end to end and use a meter and check each wire, if the cable is ok and it's connection then the motor will need a repair or replacment

[mbservice]

Check the brushes on the motor if not as Mactec said new motor required

[reabdet21]

I replaced the z axis servo and everything works great. The brushes looked good so the fault was probably within the encoder. Thanks Mactec54 and Mbservice.