Shibaura retrofit

Hi, I have a Shibaura machine and i want to retrofit but i wonder if the servo drives are analog, pwm or serial. I want to reuse the drives because they seems to work fine.
The machine controller is tosnuc 777-2.​​​​​​

Machine model VMC-55E
Servo drive models are:
AC14I-F
AC28F-D
AJ-28E
I can't find any info of them, pinout or something.Attached some pics of the drives. 

Thank you

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