1942 10EE stopped working this afternoon - need assistance with trouble shooting

I'm in the middle of a part and the forward/reverse lever no longer turns on the spindle. One minutes all is good, the next the lathe control is dead. The AC motor in the MG unit still starts and stops with the on/off switch.

Where should I start looking?

I popped the bottom panel, 17.5 VDC between GA1 and GA2 and no appreciable voltage between E1 and E2. I'm assuming this is my issue, I'm just not sure where to go next.


Background: 1942 round dial, MG unit with original controls. I power the lathe with a rotary phase converter. IIRC the exciter is a 115V unit. It's belt driven and sitting on top of the larger AC/generator combo motor.


Thanks,
Ryan

Update - com on the exciter looked a bit dirty so I cleaned it and reinstalled the brushes. In the process of doing os I pulled the cable from the end of the 3phase plug. When I rewired it I had two legs backwards - thus when facing the tailstock end of the lather both the MG and exciter were rotating clockwise.

In that configuration the lathe was operational - the drum switch tured on the spindle.

When I switched two legs, the MG and exciter were rotating counter clockwise - and back to no functioning controls.

Is the MG supposed to rotate CCW or CW? If its CCW, what's the harm in reverse (CW) to keep the lathe operational for the remainder of the day?


My problem is in the comm or brushes on the exciter - maybe it needs to be turned and undercut and a set of new brushes.

Ryan

Update #2 - the arrow on the MG indicates the motor should spin CW as viewed from the tailstock end. Cleaning the comm and re-seating the exciter brushes (and swapping 2 legs back) has the lathe back up and running.

Is Monarch still the best source for exciter brushes?

Ryan

You did a great job of diagnosing and repairing your MG Issues.
I'm surprised that the lathe ran with the MG running in the wrong direction. The brushes are angled on the exciter to lower friction and chipping of the brushes on the commutator segments. When turned the opposite way, it can cause rapid chipping and wear of he brushes..

Monarch is a good source for the brushes.

DualValve