Keysight N9038A MXE Service Guide 177
RF Preselector Section
RF Preselector Section Troubleshooting
Figure 5-5 A21 RF Preselector Input Assembly Connections - Bottom Side
Verifying Control for The SW1 Cal Switch And The SW2 Transfer
Switch
1. Remove the instrument dress cover (MP24) and the top brace (MP10).
Refer to Chapter 18, “Assembly Replacement Procedures” for instructions
on removing these covers.
2. Referring to Figure 5-4, remove W2 from A21 RF Preselector Input
assembly.
3. Turn the instrument on and allow it to complete its boot up process,
ignoring any error messages.
4. Turn the instrument self-alignment routine off by pressing System,
Alignments, Auto Align, Off.
SW1 Cal Switch Control
5. Switch the instrument input to RF Input 2 by pressing Input / Output, RF
Input, RF Input Port, RF Input 2.
6. Verify that the RF Calibrator signal is turned off by pressing Input /
Output, RF Calibrator, Off.
7. Measure the DC voltages on pins 11 through 20 on P600 of the A21 RF
Preselector Input assembly, as shown in Figure 5-6, and verify that they
are what is expected for the RF Calibrator Off as shown in Table 5-4.
If the voltage levels are incorrect the most likely cause of the problem is
the A21 RF Preselector Input assembly itself.
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