Exercising The Disc Drive; Head Cam Tool Alignment - HP 7925D Service Manual

Alignment and Adjustment
INSTRUCTIONS
[!]
LOOSEN FOUR HEAD CAM SCREWS
[}] SEAT HEAD CAMS AGAINST SIX ALIGNMENT TOOL PINS
I2l
o
TIGHTEN HEAD CAM SCREWS
Figure 3-3. Head Cam Tool Alignment
7925
h. Connect the 50-pin jumper cable, part no. 13354-60012,
between the 50-pin connector on the DSU and J1 on VO
sector PCA-A2.
i. Connect the 20-pin jumper cable, part no. 13354-60013,
between the 2o-pin connector on the DSU and the 2o-pin
connector on the head alignment peA.
I
CAUTION'
Do not plug or unplug any cables from
the data heads to read/write
preamplifier PCA-A6 or from the servo
head to track follower PCA-A5 or from
the head alignment PCA to read/write
preamplifier PCA-A6 while the heads
are loaded. Incorrect information can be
written on the disc.
j. Connect the head cable connector from the head align-
ment PCA to the head connector located at the top or
read/write preamplifier PCA-A6.
k. Connect the primary power cord to the ac mains power.
3-4
3-10. EXERCISING THE DISC DRIVE
After the DSU has been installed, the disc drive should be
exercised to relax any mechanical stresses. This is particu-
larly important when one of the mechanical assemblies
has been replaced. To exercise the disc drive, proceed as
follows:
a. Install the DSU as outlined in paragraph 3-9.
b. Set the RUN/STOP switch to STOP and the DISC
switch to the on position.
c. Install a scratch pack in the pack chamber assembly.
d. On the disc drive, set the RUN/STOP switch to RUN.
Set the unit select switch to 0 (zero).
e. On the DSU, set the FUNCTION switch to position 3
(RANDOM SEEK).
f. On the DSU, rotate the DELAY potentiometer fully
clockwise to MAX.