d. Stepper Motor Replacement.
Turn off power to the SFD.
Remove the rear cover, following the instructions in paragraph 3-6a (2)
(3) The stepper-motor wiring is connected to the stepper-motor driver (the
black anodized unit in the corner) by means of a header. Cut the cable tie securing the
harness and remove the motor wires from the header (black--terminal 1,
orange - terminal 2, yellow--terminal 3, and red--terminal 4).
(4) Manually rotate the shaft linking the stepper motor to the clutch/brake
assembly until the setscrews on the couplings are visible.
(5) Loosen the setscrews on the motor and clutch/brake sides of the shaft to
allow axial movement. Slide the shaft toward the clutch/brake so the output shaft of the
motor is disengaged from the coupling.
Loosen the tensioning pulley above the motor assembly.
(7) Remove the four motor-bracket screws, then disengage the pulley from
the cogged belt.
When handling the belt, never force it or pry it over a pulley flange. To
slide a belt in or out of position, remove the pulley.
Carefully lift out the motor by angling it slightly for clearance.
(9) Note the pulley is installed on the shaft extending from the mounting side
of the motor. Remove the pulley and save it for installation on the replacement motor
shaft. Note the motor shaft has a flat. Ensure the setscrew is resting on the flat before
(10) Install the new motor, following the above procedure in reverse.
(11) Re-tension the belt so it does not deflect more than 3/8-inch (9mm).
(12) Tighten the tensioning pulley.
(13) Reconnect the motor wiring to the header. Refer to step (3) above for
the connection points with regard to color coding. Secure the harness with a new cable