Stepper Motor - Intermec EasyCoder PX4i Service Manual

Chapter 8 — Print Unit

8.3 Stepper Motor

Description
Replacement
70
The stepper motor drives the platen roller via a short belt and the ribbon
assist roller and the ribbon rewind unit via another, longer belt. A freely
rotating pulley attached to the printer's center section makes the outside of
the longer belt drive the ribbon assist roller.
The stepper motor is driven in microsteps (8 microsteps per full step) at all
speeds.
The stepper motor is fi tted by two #T20 Torx screws to a bracket, which in
its turn is attached to the print unit gable by three #T20 Torx screws. The
pulleys of the stepper motor are permanently glued to the motor's shaft.
Replace the stepper motor as follows:
• Switch off the power and disconnect the power cord.
• Open the front and right hand doors.
• Remove the cover over the electronics compartment, which is held by
eight #T10 Torx screws, see Chapter 3.3.
• Disconnect the cable to the stepper motor from the driver board.
• Remove the tension of the belt to the ribbon rewind unit by loosening
the two #T20 screws that hold the unit, see Chapter 7.3.
• Dismantle the stepper motor from the bracket by removing the two
#T20 Torx screws.
• Free the belt from the pulley of the ribbon rewind unit and manipulate
the stepper motor so it comes free from both belts. Remove the stepper
motor.
• When putting back the stepper motor, fi t the short belt fi rst, while
letting the long belt hang loosely on the idler in a loop, through which
you can insert the pulley of the stepper motor. Do not put the long belt
around the pulley of the ribbon rewind unit until you have fi tted the
stepper motor to the bracket and checked that both belts are engaged by
the pulleys.
• Connect the cable of the stepper motor to upper connector along the
inner edge of the driver board (P10).
• Adjust the tension of the belts as described in Chapter 8.4 and put back
the cover.
Refer to illustration on the next page!
EasyCoder PX4i and PX6i Service Manual