Spindle Ground Contact And Encoder Disc; Pack Lock - HP 7925D Service Manual

7925
Remove the bottom cover (6, figure 6-5) of the
spindle.
The spindle bottom cover is installed by reversing this
procedure. When installing the bottom cover, tighten
the three mounting screws (7) to 12 inch-pounds.
5-27. SPINDLE GROUND CONTACT
AND ENCODER DISC
I
To replace the spindle ground contact (8, figure 6-5) or
an encoder disc (9), proceed as follows:
a. Perform the preparation for service outlined in para-
graph 5-2.
Removal and Replacement
painful eye irritation upon contact
and for some people skin inflam-
mation (dermatitis). When using
this lubricant, hand protection
(latex gloves) should be worn and
care should be taken to keep the
lubricant away from eye tissue.
Note: If the lubricant (part no.
6040-0084) gets on the
skin, a waterless hand
cleaner is recommended to
remove the lubricant.
h. Place the encoder disc in position in the spindle.
g. If the encoder disc requires replacement, replace it
with a new encoder disc.
Note: For proper operation of the disc drive
the part number on the encoder disc
must face toward the bottom cover (6)
of the spindle.
I
b.
c.
e.
f.
Disconnect the ac power cord from the ac mains
power.
Open the front door of the disc drive and remove the
front shield (15, figure 6-1).
Remove the bottom cover (6, figure 6-5) of the
spindle.
Remove encoder PCA-A10. (Refer to paragraph 5-25.)
While holding the spindle motor hub, use a wrench to
remove the spindle ground contact.
a.
b.
c.
d.
e.
f.
If the disc drive is in an operating mode, set the
RUN/STOP switch to STOP.
Allow the spindle to halt (approximately 30 seconds).
The DOOR UNLOCKED indicator will light, which
means that the spindle has stopped rotating, the door
unlock solenoid is energized, and it is safe to open the
pack chamber door.
Remove and store the disc pack. Be sure to leave the
pack chamber door open.
Disconnect the ac power cord from the ac mains
power.
Rotate the spindle hub (see figure 5-6) until one of the
allen screws is visible through one of the large holes
in the spindle hub. Remove the allen screw and re-
place it with the hub locking bushing.
Remove the pack lock retainer (1, figure 6-5) using
the pack lock retainer tool which fits on the 100 foot-
pound torque wrench. Throw out the old retainer.
i. If the spindle ground contact requires replacement,
replace it with a new spindle ground contact.
j. Attach the spindle ground contact to the spindle shaft.
k. Replace encoder PCA-A10. (Refer to paragraph 5-25.)
I
1.
Replace the bottom cover (6) of the spindle.
m. Replace the front shield (15, figure 6-1).
n. Restore ac power to the disc drive.
5-28. PACK LOCK
To perform the pack lock replacement procedure requires
the special tool package for the service kit, part number
07920-67802. To change a pack lock, proceed as follows:
WARNING
The lubricant (part no. 6040-0084)
used in this procedure can cause
Change 1
g. Remove the pack lock assembly (2). Be sure to leave
the compression spring (3) in the spindle assembly.
Throw out the old pack lock assembly.
ALLEN SCREW \
REF 7311-72
Figure 5-6. Spindle Screw Locations
5-15