Servicing The Air Circulation System; Pack Lock Lubrication - HP 7925D Service Manual

Maintenance
a. Remove and store disc pack. Ensure that the disc pack
is stored in the proper storage container.
b. Disconnect the ac power cord from the main power
source.
c. Remove front and rear doors.
d. Remove the side panels and shroud. (Refer to Section
V, Removal and Replacement.)
Note: Remove components only to the extent
necessary to gain adequate access for
servicing.
e. Record the date the preventive maintenance was per-
formed on the preventive maintenance label. If a new
label is needed, a new one (HP part number 7120-7288)
can be ordered from the nearest HP Sales and Support
Office.
f. Proceed with the preventive maintenance procedures.
7925
h. Set RUN/STOP switch to STOP, DISC switch and
circuit breaker to OFF, and disconnect power cord
from source of ac power.
i. If observed air pressure is less than minimum accept-
able limits, remove and inspect the prefilter.
j. If the prefilter is dirty, replace the prefilter. (Ensure
that the prefilter airflow direction arrow is facing in
the proper direction.)
k. After replacing the prefilter, remeasure the air
pressure.
1. If the air pressure remains below acceptable limits
after the prefilter has been replaced, replace the abso-
lute filter. (Refer to Section V, Removal and
Replacement.)
m. Replace the shroud.
Servicing the air circulation system consists of measuring
the air pressure at the outlet on the pack loading assem-
bly, and periodic replacement of the prefilter and/or the
absolute filter. To measure the absolute filter air pressure,
proceed as follows:
Pack lock (2, figure 6-5) lubrication is performed at every
preventive maintenance interval. The pack lock lubrica-
tion tool (part no. 07920-20086) and the lubricant (part no.
6040-0084) are required to perform this procedure.
2-13. SERVICING THE AIR CIRCULATION
SYSTEM
2-14. PACK LOCK LUBRICATION
a. Remove the shroud. (Refer to Section V, Removal and
Replacement.)
b. Connect the power panel assembly power cord to a
source of ac power.
c. Set the power distribution unit circuit breaker to ON
and the disc drive DISC switch to the on position.
d. Install a scratch pack and close the pack chamber
door.
e. On the disc drive, set the RUN/STOP switch to RUN
and wait until the heads load.
f. Using the air pressure measuring gauge with the air
pressure probe assembly, place the probe over the air
pressure outlet. (See figure 2-4).
The lubricant (part no. 6040-0084)
used in this procedure can cause
painful eye irritation upon contact
and for some people skin inflamma-
tion (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.
a. If the disc drive is operating, set the RUN/STOP
switch to STOP.
Note: Meter may peg when filter is new.
g. Observe the air pressure. Check that air pressure is
equal to or greater than the minimum acceptable
limits given below:
MINIMUM
NORMAL ACCEPTABLE
OPERATION LIMITS
(Inches of water) (Inches of water)
LINE
FREQUENCY
(Hz)
50
60
>
0.30
>
0.30
0.30
0.30
b. 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.
c. Remove and store the disc pack. Be sure to leave the
pack chamber door open.
d. Disconnect the ac power cord from the ac mains
power.
2-8