Pen Solenoid; Pen Drive Motor And Belt - HP 7475A Service Manual

Model 7475A
COUPLER
RING
PAPER DRIVE
SHAFT COUPLER
7475-A-21-1
Section VI
MOTOR SHAFT
COUPLER
RUBBER
0-RINGS
Figure 6-12. Paper Drive Coupler Parts
i.
Reconnect the cables to the PCA. To prevent elec-
trical interference, ensure the motor wires are
intertwined up to the connector and fitted away
from the encoder assembly.
6-68. PEN SOLENOID
a. Remove the top case. Refer to
Top Case Removal.
b. Loosen the paper drive motor clamp enough to
slide the motor to the right about 2 cm (3/4 in.).
See Figure 6-11. (Lift the right end of the motor
slightly to release the motor from the chassis.)
c. Disconnect the solenoid cable from J2 on the
printed circuit assembly. See Figure 6-10.
d. Loosen the solenoid mounting screw enough to
allow removal of the solenoid. See Figure 6-13.
e. When replacing the motor, make sure that the 0-
rings on the drive shaft coupler and the motor
shaft coupler fit inside the grooves of the coupler
ring, and the boss (key) on the underside of the
motor casting fits into the corresponding hole in
the chassis. See Figure 6-12.
f. Make sure the pen carriage slider rod is all the
way to the left, then replace the motor clamp. The
arm on the clamp should hold the slider rod to
the left. Tighten the clamp screw securely.
g. Loosen the clamping screw in the paper drive
shaft coupler just enough to allow the coupler to
slide on the shaft. Make sure the nut remains in
the coupler.
h. Hold the drive shaft to the left by pushing (with a
finger) on the left gritwheel, and push the drive
shaft coupler to the right (with another finger) so
that the coupler parts fit together snugly. Tighten
the shaft coupler clamping screw securely.
6-69. PEN DRIVE MOTOR AND BELT
6-70. To remove the pen drive motor and belt, proceed
as follows:
a. Remove the top case. Refer to Top Case Removal.
Do not remove the encoder printed
circuit assembly or drive pulley from
the motor. The entire assembly must
be assembled and calibrated at the
factory.
b. Disconnect the pen drive motor cable (twisted pair)
from J5 and the flat encoder cable from J6 on the
main printed circuit assembly. See Figure 6-13.
c. Remove the belt tensioner by pressing downward
on the tensioner and sliding the tang at the
bottom out of the slot in the chassis. See Figure
6-14.
6-U