Keysight FieldFox Handheld Analyzers Service Guide 157
Repair and Replacement Procedures
Removing and Replacing the Measurement Group Assemblies
Replacing the RF Assembly Including the A4 RF Board
(N995xA, N996xA)
1. Separate the front and rear cases. Refer to “Separating the Front and Rear
Cases” on page 115.
2. Remove all measurement group assemblies as one unit. Refer to
“Removing All Measurement Group Assemblies as One Unit” on page 136.
3. Refer to 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.
4. Refer to Figure 7-35. Remove the nineteen shield screws (3) and the two
System board screws (4).
5. Refer to Figure 7-36. The System board and shield can now be separated
from the RF assembly.
6. Place the System board on the new RF assembly. Refer to Figure 7-37.
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.
7. Refer to 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.
8. Place the RTC board onto the System board shield with the battery
towards the shield and secure with the two screws. Torque to 9 in-lbs.
9. Reconnect W17 to the System board.
10.Perform the steps under “Final Assembly Procedure” on page 164.
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.
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