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
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