Head Cam; Head Cam Support - HP 7925D Service Manual

To replace a head cam (11, figure 6-7), proceed as follows:
a. Perform the preparation for service outlined in
paragraph 5-2.
7925
h. Remove the two screws (2) that secure the velocity
transducer (1) to the actuator assembly.
1.
Carefully slide the velocity transducer, with the ve-
locity transducer shaft inside it, out from the rear of
the actuator assembly.
5-22.
HEAD CAM
Removal and Replacement
I
CAUTION
I
The velocity transducer shaft contains a
calibrated magnet. To avoid damage to
the velocity transducer shaft, avoid con-
tact by the magnet end of the shaft with
ferrous or magnetic materials.
j. Carefully slide the velocity transducer shaft out from
the rear of the velocity transducer.
To install a new velocity transducer and/or velocity trans-
ducer shaft, proceed as follows:
I
CAUTION
I
Exercise extreme care when replacing
the velocity transducer. A slight torque
on the back section will break the wires
inside the assembly.
a. If the velocity transducer requires replacement, re-
place it with a new one.
b. Gently push the velocity transducer into the back of
the actuator assembly and secure it in place with the
two screws previously removed.
I
CAUTION
I
The velocity transducer shaft contains a
calibrated magnet. To avoid damage to
the velocity transducer shaft, avoid con-
tact by the magnet end of the shaft with
ferrous or magnetic materials.
c. If the velocity transducer shaft requires replacement,
replace it with a new one.
d. Insert the rod end of the velocity transducer shaft into
the opening at the end of the velocity transducer.
b. Disconnect the ac power cord from the ac mains
power.
c. Remove the shroud. (Refer to paragraph 5-3.)
d. Remove the front frame assembly (refer to paragraph
5-7) and then remove the pack chamber assembly
(refer to paragraph 5-9). Remove the data heads and
the servo head. (Refer to paragraph 5-18.)
e. Remove the two screws (12) which secure the head
cam to the head cam support.
f. Install the new head cam on the head cam support by
loosely tightening the two head cam screws (12).
g. Loosen the two screws (12) on the other head cam (11).
h. Install the head cam alignment tool, part no. 13354-
60001, on the spindle hub. (See figure 5-4.) Ensure
that the head cams mate with the head cam align-
ment tool.
i. Adjust the cams to position with the head cam align-
ment tool. (See figure 5-5.)
j. Tighten the cam securing screws (12) to 7 inch-pounds.
k. Remove the head cam alignment tool. Replace the
data heads and the servo head. (Refer to paragraph
5-18,)
I.
Replace the pack chamber assembly (refer to para-
graph 5-9) and then replace the front frame assembly
(refer to paragraph 5-7).
m. Measure the absolute filter air pressure as outlined in
paragraph 2-13.
n. Replace the shroud. (Refer to paragraph 5-3.) Restore
ac power to the disc drive.
To replace a head cam support (14, figure 6-7), proceed as
follows:
e. Using a slender tool of nonmagnetic material (such as
the eraser end of a pencil), push on the magnet end of
the velocity transducer shaft until the rod end extends
through the hole in the carriage assembly.
5-23. HEAD CAM SUPPORT
f. Tighten the setscrew (4) on the carriage assembly to
secure the velocity transducer shaft.
g. Replace the card cage chassis. (Refer to paragraph
5-14.)
h. Replace the shroud. (Refer to paragraph 5-3,) Restore
the ac mains power to the disc drive.
a. Perform the preparation for service outlined in
paragraph 5-2.
b. Disconnect the ac power cord from the ac mains
power.
c. Remove the shroud. (Refer to paragraph 5-3.)
5-11