Some notes on the Microbot Alpha II (or 'Teachmover') robot arm.
The base of the arm contains one PCB, marked “Microbot Inc. Alpha Motor Drive Assy: 10131 Rev A” (serial 636). It contains 12 single-phase stepper drivers (a combination of RIFA and ST PBL3717 ICs), as well as two LM339N quad comparator ICs.
The PBL3717 drivers can output 5-1200mA per phase at 10-50v, with 5v logic, and rather than 'typical' step/dir control, they have a 'phase' and two-pin selectable current level input. They are capable of full or half stepping.
SW4 is unused
Power socket pinout, as seen facing the board
| _______ | | | | | | | |1 | | | | | o o | +5v |0 | | | | | | |0 | | | | RST | o o | |µ | |_| | | | |F | | +VMotor | o o | GND | | | |_______| |__| | |__________________________________ \___________________________/ DB-50 Connector