Here is some of the information I've managed to gather from the literature. The maintenance manual for the machine gives a pretty good description of the various components. I'll include any information that seems pertinent (even if I have no clue what it denotes).
Axes servo drives - Gettys N360 SCR They are 3-phase half-wave drives. I have the factory manual for the drives. It includes diagrams and schematics, but some of it is tough to read because an obvious printing error jumbled up some of the text and placed some of it on the schematics.
The axes servo motors are Gettys permanent magnet motors. The tachometer produces 9.5 VDC for every 1000 RPM, and the armature voltage at 1000 RPM is 34.2V +/- 10%.
The encoders are 500-line optical incremental encoders. The literature gives a bunch of specs for them, but I have no idea what most of them mean. For example, the outputs are described as quasi-sinusoid or square wave single channel or dual channels in quadrature. I sure hope I don't have to understand such concepts if I am to be successful with this retrofit!
The spindle uses a size 3 Fanuc AC spindle drive and motor. If I understand correctly, it is a servo-type motor. It is rated at 3.7 kW (5 HP) continuous and 5.5 kW (7.5 HP) for 30 minutes. The base speed is 1500 RPM and the max is 6000. The input command voltage goes between +10V DC (max speed) and 0V (halt). Power supply is 200/220V +10% / -15% at 50/60 Hz +/- 1 Hz. Velocity feedback is provided by a pulse generator. The Fanuc part numbers for the spindle motor and drive are listed, but I assume those are not necessary.
Anyway, I hope that some of this information will be able to help move me in the right direction. As I said, I just assumed that it would be best to replace the servo drives. This is mainly because they are so old (from the early 80s). There is a factory-installed 4th axis on this machine. So, there is a spare drive on hand. The original rapid speed was 200 IPM (with feeds topping out at 100 IPM), so changing out the drives probably wouldn't turn a fast machine into a slow one. If more detailed information is needed, please let me know. The literature I have seems quite detailed, so there is a good chance it will have any info that might help. Thank you to all for taking time to read my posts and help me with this project! I'll be damned if I'm going to end up like these guys.http://www.youtube.com/watch?v=x3RgyZRgshA