Pack Detector Assembly Removal And Replacement; Data And Servo Head Removal And Replacement - HP 7925D Service Manual

Removal and Replacement
7925
d. Remove the two screws at the top of the panel and the
two screws on the underside of the operator panel.
e. Pull the panel out far enough to gain access to the
PCA.
f. Disconnect the plug from jack A12J1 on the fault
indicator PCA.
g. From the rear side of the PCA, remove two nuts (3,
figure 6-9) on mounting posts and lift off PCA.
To replace fault indicator PCA-A12, perform the above
steps in the reverse order.
Note: When fault indicator PCA-A12 (2, figure
6-9) is replaced, ensure that the letters
"hp" on the back of PCA-A12 are ori-
ented so they are on the top side of the
PCA when it is installed in the operator
panel (9, figure 6-9).
5-17. PACK DETECTOR ASSEMBLY
REMOVAL AND REPLACEMENT
To remove the pack detector assembly, proceed as follows:
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,)
d. Open the front door and remove the front shield (15,
figure 6-1).
DETECTOR
IN THE
DOWN
POSITION
e. Remove the front frame assembly. (Refer to para-
graph 5-7.) Remove pack chamber assembly. (Refer to
paragraph 5-9.)
7311-87
Figure 5-1. Pack Detector Assembly
f.
Remove the two screws that secure pack detector as-
sembly to the mainframe, and remove the assembly.
To replace the pack detector assembly, perform the above
steps in the reverse order. When the pack chamber is back
in place, measure the air pressure as outlined in para-
graph 2-13. When replacing the assembly, ensure that the
detector is in the down position as shown in figure 5-1.
5-18. DATA AND SERVO HEAD
REMOVAL AND REPLACEMENT
The data and servo heads are removed and replaced in the
same manner. When any head is replaced, head alignment
must be performed as part of the replacement. To remove a
data or servo head, proceed as follows:
5-6
a. Perform the preparation for service outlined
III
paragraph 5-2.
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\.
e. Remove card cage PCA's. (Refer to paragraph 5-11.)
f. Remove card cage chassis. (Refer to paragraph 5-14.)