Problem- OHM Servo Motors

[KLUCAS4]

How would you go about OHM a servo motor? I understand how to do it but, I dont. The motor I would like to check out has a round plug how do I know which is T1, T2, and T3? The Fanuc Engineers wants me to ohm the z axis motor to ground. Does

[Al_The_Man]

It sounds like this is either a BLDC or an AC servo motor, there would normally be 3 power leads and a ground wire on any power plug to the motor.
If so there would be very low resistance between any of the three power leads to the stator windings. In the order of a few ohms, if that, if there is a fourth Ground lead, there should be no continuity between the three stator leads and ground.
IOW between any of the 3 power there should be the same resistance.
Al.

[KLUCAS4]

Thanks Al. Yes I am pretty sure its an AC servo motor its on A Cin Milacron. She is my old girl but with Acramatic control and Fanuc Drives its hard to get the Fanuc guys to pin point my problem since the alarms are not from a Fanuc Control. They seem to think the srvo amp Is losing its ready signal but, they want me me to ohm the z axis motor to grd then go from there. The machine will come up and run then after about 30min to an hr it loses the servo amp alarms out with ( x axis sero drive failure) then will not restart.

[KLUCAS4]

Just wanted to update this it turned out the servo drive was ok along with the motors. The Fanuc Engineers @ Fanuc America had me to check lead to lead on pins 3 &4 on the servo drive for 100V mine was 7V. So after tracing the wire and checking the volts there it was 110 on common side so I OHM the (Ice Cube Relay from directions from machinetoolhelp.com) and the relay OHM out ok. So I got to tracing back the little blue wires on the bottom of the relay recepticle back to my I/O boards and noticed on one of them no led's were on like the other 3. So I powered down the machine pulled the card out then reseated the board and now everything is working correctly.