HP 7925D Service Manual page 72

Alignment and Adjustment
(NOT TO SCALE)
'--0.051 em (0.020 in.)
REF 7311-53
Figure 3-17. Actuator Crash Stop Clearance
Note: Do not stop the spindle while the DSU is
set to FUNCTION 7. If the spindle must
be stopped, remove any tools from the
actuator assembly; set the DSU to
FUNCTION 1; press the START push-
button, then the STOP pushbutton; and
then set the RUN/STOP switch to STOP.
d. Verify that the head alignment is within a reading of
0.0 ±5 on the HEAD ALIGNMENT meter.
e. Repeat steps b through d for each data head to be
checked.
f. Perform the data head alignment procedure for each
data head that is out of tolerance.
3·20
7925
g. After this procedure is completed and all tools have
been removed from the actuator assembly, set the
DSU to FUNCTION 1.
h. On the DSU, press the START pushbutton and then
press the STOP pushbutton. Set the RUN/STOP
switch to STOP.
3-19. DATA HEAD ALIGNMENT. The data head
alignment procedure should be performed when a servo
head has been replaced, a data head has been replaced, or
when the data head alignment check reveals that a data
head is out of tolerance. To align a data head, proceed as
follows:
I
CAUTION
I
Do not insert the head alignment tool into
the servo head adjustment hole, which is
the fifth from the top (see figure 3-5),
otherwise all data heads will require
realignment.
a. Perform the warmup procedure outlined in paragraph
3-13.
b. On the DSU, set the FUNCTION switch to position 7
and press the START pushbutton. After the 5-second
cycle is complete, torque all data heads to be aligned
to 5 inch-pounds.
Note: Do not stop the spindle while the DSU is
set to FUNCTION 7. If the spindle must
be stopped, remove any tools from the
actuator assembly; set the DSU to
FUNCTION 1; press the START push-
button, then the STOP pushbutton; and
then set the RUN/STOP switch to STOP.
c. Select the data head to be aligned using the binary
combination of toggle switches H8 (CII), H4, H2, and
HI. Press the START pushbutton and wait for the
completion of the 5-second cycle.
d. Insert the head alignment tool, with the "L shaped"
handle end pointing upward, into the data head
alignment hole and adjust the head until the meter
deflection is between a reading of -10 and
+
10 units.
Remove the alignment tool. (Note that the tool
pointer and meter pointer move in the same
direction. )
e. Tighten the data head to 7.5 inch-pounds.
f. Insert the alignment tool and carefully adjust the
data head for a reading of 0.0 ± 1 on the HEAD
ALIGNMENT meter. Remove the alignment tool.