Agilent Technologies FieldFox MW N9913A, Service Manual, Page: 129 / 156

N9927-90003 7-35
FieldFox Analyzer Repair and Replacement Procedures
Removing and Replacing the Measurement Group Assemblies
Replacing the A5 System Board
1. Separate the front and rear cases. See “Separating the Front and Rear Cases” on page 7-10 .
2. Remove all measurement group assemblies as one unit. Refer to “Removing All Measurement
Group Assemblies as One Unit” on page 7-27 .
3. Remove the I/O side panel. Refer to “Replacing the I/O Side Panel, Doors, and Gasket” on page
7-14 .
4. Disconnect cable W3 and W4 from the A5 System board.
5. Refer to Figure 7-22 . Remove the RTC board. Refer to “Replacing the Real Time Clock (RTC)
Battery Located on the A5 System Board Shield” on page 7-31 .
6. Remove the System board shield by removing the nineteen screws (item 2). Discard the screws, new
ones are provided in the Repair and Re-assembly Kit .
7. Refer to Figure 7-23 . Remove the four screws (item 2) that secure the A6 SOM board (item 1) to the
A5 System board. Discard these screws; new ones are provided in the Repair and Re-assembly Kit .
8. Unplug the A6 SOM board from the A5 System board.
9. Refer to Figure 7-24 . Remove the two screws (item 1) from the A5 System board, lift it up from the
RF bottom shield, and unplug it from the A4 RF board connector. Discard the screws, new ones are
provided in the
Repair and Re-assembly Kit .
10. Refer to Figure 7-25 . Plug in the new A5 System board to the A4 RF board, over the new gasket, and
aligned with the three dowel pins in the RF bottom shield. Make sure the bullets are straight up when
connecting the System and RF boards.
11. Refer to Figure 7-23 . Replace the SOM board onto the System board. Install four new screws (item 2)
from the Repair and Re-assembly Kit and tighten them in the torque sequence indicated by the circled
numbers (1 - 2 - 3 - 4) in the illustration.
12. Refer to Figure 7-26 . Place the System shield onto the System board by aligning the dowel pins.
Replace the nineteen shield screws. Torque these screws (plus the two System board screws, #13 and
#21) in the sequence shown by the circled numbers (1 - 21). Repeat this torque sequence one
additional time. Torque to 12 in-lbs.
13. Place the RTC board onto the System board shield and secure with the two screws. Torque to 9 in-lbs.
14. Remove the System board to FPIB cable (W14) from the old A5 System board and install it on the
new board.
15. Reinstall the I/O side panel. Refer to “Replacing the I/O Side Panel, Doors, and Gasket” on page
7-14 .
16. Perform the steps under “Post-replacement Procedure” on page 7-44 .