Keysight Technologies FieldFox N9913A Service Manual page 157

Repair and Replacement Procedures
Removing and Replacing the Measurement Group Assemblies
Replacing the RF Assembly Including the A4 RF Board 
(N995xA, N996xA)
Do NOT loosen the 2.4 mm connectors that interface the RF assembly to the airline/test ports.
Doing so will invalidate the RF assembly calibration.
1. Separate the front and rear cases. Refer to
2. Remove all measurement group assemblies as one unit. Refer to
3. Refer to
4. Refer to
5. Refer to
6. Place the System board on the new RF assembly. Refer to
7. Refer to
8. Place the RTC board onto the System board shield with the battery
9. Reconnect W17 to the System board.
10.Perform the steps under
Keysight FieldFox Handheld Analyzers Service Guide
Cases" on page 115.
"Removing All Measurement Group Assemblies as One Unit" on page
Figure 7-35. Remove the two screws (2) attaching the RTC board
(1) to the System shield. Unplug cable W17 and remove the RTC board.
Figure 7-35. Remove the nineteen shield screws (3) and the two
System board screws (4).
Figure 7-36. The System board and shield can now be separated
from the RF assembly.
Plug in the A5 System board to the A4 RF board, 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.
Figure 7-38. 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.
towards the shield and secure with the two screws. Torque to 9 in-lbs.
"Separating the Front and Rear
"Final Assembly Procedure" on page
136.
Figure 7-37.
164.
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