[stagen]

Trying to source a known working x/y axis DC servo, type MT30M4-38, for my Partner 1 mill.
My attempt at cleaning up the commutator has left me with a motor that runs away when the reset button is pressed.

[Jim Dawson]

If the tach, encoder (if equipped), or armature wiring was reconnected incorrectly, the motor would likely run away on reset. You might doublecheck wiring before buying a rather expensive motor.

[stagen]

Well, I swapped the armature leads around at the terminal block in the electrical cabinet, and now she’s working. Those two were the only wires cut and reconnected when I removed the motor. Colors were matched red/red, black/black, so that didn’t cause the issue. I’m wondering if the field coil lost polarity when I disassembled the main housing? Only thing I could find from a brief google of the issue, I’m no motor expert. Anyways, it’s working again so I’m happy.

[Jim Dawson]

Well, I swapped the armature leads around at the terminal block in the electrical cabinet, and now she’s working. Those two were the only wires cut and reconnected when I removed the motor. Colors were matched red/red, black/black, so that didn’t cause the issue. I’m wondering if the field coil lost polarity when I disassembled the main housing? Only thing I could find from a brief google of the issue, I’m no motor expert. Anyways, it’s working again so I’m happy.

Who knows, that is a strange one. Happy to hear you got it working.