Service manual

Operating Principles
EPSON FX-880/FX-1180 Service Manual
2-11
Platen Gap Adjustment Mechanism
The platen gap (the gap between the platen and the printhead) can be adjusted to allow the printer to use
paper of different weights or thicknesses. When the platen gap adjust lever is moved forward or
backward, the carriage guide shaft rotates. Because the carriage guideshaft is eccentric at the ends, this
rotation moves the carriage either toward or away from the platen, and changes the platen gap. The
platen gap (PG) sensor detects the position of the adjust lever. The correct platen gap is 0.38 mm ± 0.02
mm with the adjust lever set to position 0. If the lever is set to position 2 (the 5th slot from the top) or
higher, the printer goes into copy mode.
Figure 14. Platen Gap Adjustment Mechanism
Paper Feed Motor
The paper feed (PF) motor advances the paper at minimum increments of 1/216 inch. This motor is a 2-2
phase, constant-voltage stepper motor. CPU ports P70 to P73 generate phase signals to drive the motor.
PFA to PFB are turned on or off within the µPA1476H (IC1), depending on the phase data sent from the
CPU.
When pin A19 of the CPU goes HIGH, D1 outputs +35 volts to hold the motor stationary.