Hi
Randy is right. They used the 24V line for the stepper.
The 12V line was used for the analog electronics.
Still, as I recall, the 24V didn't need exact regulation.
I'd have to check my schematics for the drives.
Dwight
Be sure to check the labels on the stepper motor. Some years ago I had a
brief "aquintance" with a SSSD drive from Control Data. I binned it
immediately, as it showed that the steppermotor needed 115VAC !
Nico