Thanks Phil. This is not a retrofit, just something to keep the spindle turning at a desired speed for an interim.
Currently undecided if a true retrofit to AC, or another repair/replacement of the spindle drive mother board this round. It seems no matter how many hours are on them, they fail after some years ('06, 13[or so?], 16 and now 2020). The parts are getting more scarce, used spindle drives were $600, now $3k and another 14yr older... it weren't for fresh windings, bearings and brushes just a couple years ago the motor would have likely been nixed at this point (the 200vAC-DC box was replaced with NOS in '16 when the top board was last repaired).
The DC to DC driver linked in the above post has logic, feedback, pulse generator detection, hall effect throttle control, and programmable over-load shut down etc. Here's the datasheet with programming parameters:
LINK
Wouldn't a small circuit with logic be able to send a 0-5v signal to the DC/DC driver input case of an overload on the armature (or use the input current draw protection in the software)? The controller is pretty advanced, and is typically used with LiPo batteries which have a much less safety margin than regulated 208vAC/200vDC stable shop service.
It's amazing when realizing the huge circuit boards of the past have been replaced with tiny bitty things. My Fluke fuse blew and of course didn't have a spare - borrowed the neighbors DMM and it was this little tiny red foreign-built box that couldn't weigh more than a couple ounces, and it got the job done, anyways. Out of curiosity, popped the screws out to look inside, and there was a board the size of a Zippo lighter, and with all the components, maybe 1/8" thick. Shoot, look at tricorders ('err, smartphones). I still have the TripleT in the bottom of the toolbox, it's quite hefty, even for the Fluke.
Am I in left field trying this? Theoretically, it wouldn't take much firmware to actually integrate this DC/DC drive into the System 6 NC, but would rather do a full AC conversion - again this is a temporary "band-aid". Found someone parting a working (wore out ways) machine a few years newer that will almost be "plug-and-play", but all the wiring has already been cut, and uses newer connectors (lots and lots of patch wiring, ugh).