Urgent Help - PM 940M down. Motor issue

[Sticks]

2023 mfg PM 940M

My Mill blew the run capacitor a couple days ago without warning - no symptoms.

I replaced it with a like capacitor, and after 2 uses, the mill started not turning up to full speed going rev (normal operation) for 2-5 seconds. It would spin right up going fwd, then switch back to rev and it would occasionally start right up, unless it was sitting for an hour or so, then right back to a slow start.

Today, it will not spin up at full speed in either direction.

I tested the capacitors and they are both still within spec. This leads me to think that either a winding in the motor has gone out, or the inertia board has failed.

Anybody know the specs (+/- xx.xxx ohms) for continuity testing the motor at the 4 wires - Rd [U1], Rd [U2], Gr/Y [V1], Wh [V2], and Or [W1].

Also need to know how to remove the motor. Is it just the 4 bolts on top of the head, or do I need to pop the top cover off, in which case, how?

 

[RJSakowski]

I would check the forward/reverse switch. Your symptoms sound like an intermittent open somewhere. Maybe a bad wiring connection somewhere. Was your replacement run capacitor a non electrolytic? Unlike start capacitors, the run capacitor is in the circuit whenever the motor is engaged.. An electrolytic would fail quickly under those conditions.

 

[markba633csi]

Sounds like the start winding is partially shorted or there is a problem with the internal start switch
I don't know what the windings would measure- PM might be able to help there
You should still be under warranty - might be new motor time

 

[Sticks]

I am getting 220 on all legs (Leg to Leg / 120 Leg to ground) when the switch is engaged at the motor.

The wiring diagram is less than helpful Switch to motor is Z1, Z2, U1, U2. non specific as to what each one is (fwd/Rev)

 

[B2]

Which motor do you have? Maybe a picture of the motor plate, showing brand, model, etc. I also have a 940M-CNC-VS with 3 phase 1.5KW motor. But I have had it a few years so it maybe different from yours and yours might be wired differently?

 

[markba633csi]

Voltages sound ok (120v to ground on all 4 wires in F/R would make sense for 240v circuit); problem is motor itself

 

[Sticks]

Here is the motor tag

 

[Sticks]

Voltages sound ok (120v to ground on all 4 wires in F/R would make sense for 240v circuit); problem is motor itself

Poop. I hope not. Working on finding a replacement in case PM calls me out of warranty. Little under 1 year in my possession. Took delivery 07/25/2023

 

[markba633csi]

Supposed to be 3 year warranty according to the website

 

[Ulma Doctor]

A picture of the control board may help to troubleshoot