Pen Carriage, Penholder, And Damper Removal; Pen Carriage - HP 7475A Service Manual

Model 7475A
e. Slide the pen drive motor into place and tighten
the clamp. (A boss on the side of the motor
casting must fit into a notch in the chassis.)
f. Place the belt over the drive pulley.
g. Replace the belt tensioner and spring. Move the
pen carriage from side to side and make sure the
belt and pulleys are properly aligned.
h. Connect the motor and encoder cables to the main
printed circuit assembly. To prevent electrical
interference, ensure the motor wires are inter-
twined up to the connector and fitted away from
the encoder assembly.
i.
Replace the top case, making sure the PAPER
LOAD/HOLD lever extends through the case and
the tabs inside the front of the case align properly
above and below the base plate.
6-72. PEN CARRIAGE, PENHOLDER, AND
DAMPER REMOVAL
6-73. To remove the pen carriage, penholder, and damper,
proceed as follows:
a. Remove the top case. Refer to Top
Case
Removal.
b. Remove the paper drive motor. Refer to Paper
Drive Motor Assembly Removal.
c. Remove the pen solenoid. Refer to Pen Solenoid
Removal.
d. Remove the pen drive motor. Refer to Pen Drive
Motor and Belt Removal, steps b., c., and d.
e. Slide the belt from the pen carriage and move the
pen carriage to the left. See Figure 6-15.
Two springs will be released during
the next two steps -the pen down
spring and a preload spring on the
slider rod between the carriage and
penholder parts. Proceed carefully.
f. Remove the end bearing cap while sliding the
pen
lift bar to the right and out of the carriage as-
sembly. See Figure 6-14. (To replace the end cap
on the lift bar, merely slide the cap onto the bar.)
g. Move the slider rod to the right just far enough to
release the left end of the rod from its mounting.
See Figure 6-13. Slide the rod to the left and out of
the carriage/penholder assembly.
Section VI
h. The plastic damper is merely pressed into the
carriage and penholder parts. Remove carefully.
6-7 4. To reassemble, proceed as follows:
a. Carefully replace the damper.
b. Place the pen down and preload springs into
position and hold the parts together while insert-
ing the slider rod from the left. Make sure the
preload spring is positioned over the rod properly
so that it does not drag on the slider rod.
c. Replace the slider rod in the chassis.
d. Replace the pen lift bar.
e. Replace the pen solenoid.
f. Replace the paper drive motor, making sure that
the rubber 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 under
side of the motor casting fits into the correspond-
ing hole in the chassis. See Figure 6-12.
g. 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.
h.
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.
i. 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.
j. Reconnect the cables to the PCA.
k. Replace the pen drive motor and belt as instructed
in Pen Drive Motor and Belt.
1.
Measure the pen down force by using a gram
gauge. To do this, it is necessary to apply power
to the plotter, and select and lower a pen onto the
platten. Place the tip of the gram gauge under the
lip of the pen body and check that the pen just
starts to lift with 19 ±10 grams. See Figure 6-16.
If
the pen does not start to rise within IO to 29
grams, replace the pen down spring. Refer to
Table 4-3 for part number.
m. Replace the top case, making sure the PAPER
LOAD/HOLD lever extends through the case and
the tabs inside the front of the case are aligned
properly above and below the base plate.
6-13