Keysight N5221A/22A Service Guide 4-45
Troubleshooting
Measurement System Troubleshooting
If the measured signal is missing on any receiver (other than the R1
receiver noted above) and the analyzer does not have receiver attenuators,
replace the A23 or A24 mixer brick, whichever is appropriate. Refer to
“Removing and Replacing the A23 and A24 Mixer Bricks” on page 7-37.
If the measured signal is missing on the A, B, C, or D receivers and the
analyzer has receiver attenuators, continue testing at “Checking the A42,
A43, A44, and A45 35-dB Receiver Step Attenuators” on page 4-45.
Checking the A33 Reference Mixer Switch
1. Remove the front panel REF 1 jumper and connect a spectrum analyzer to
the front-panel REF 1 SOURCE OUT connector.
2. If the measured signal is present, replace the A23 mixer brick. Refer to
“Removing and Replacing the A23 and A24 Mixer Bricks” on page 7-37.
3. If the measured signal is not present replace the A33 reference mixer
switch. Refer to “Removing and Replacing the A33 Reference Mixer
Switch” on page 7-43.
Checking the A42, A43, A44, and A45 35-dB Receiver Step Attenuators
1. Locate the appropriate semirigid cable at the output of the receiver step
attenuator to be checked:
— Options 219 and 419
— Port 1; W88 of A34
— Port 2; W94 of A37
— Port 3; W90 of A35
— Port 4; W92 of A36
2. Disconnect the appropriate semirigid cable from the output of the step
attenuator.
3. Connect the spectrum analyzer to the open step attenuator connector. Set
the spectrum analyzer to measure a signal at 800 MHz.
4. If the 800 MHz signal is not present, replace the receiver step attenuator.
Refer to “Removing and Replacing the A34–A37 Source Attenuators, the
A38–A41 Bias Tees, and the A42–A45 Receiver Attenuators” on page 7-45.
5. If the 800 MHz signal is present, replace the associated mixer brick, A23 or
A24. Refer to “Removing and Replacing the A23 and A24 Mixer Bricks” on
page 7-37.
Checking the A20 IF Multiplexer Board
1. Locate each of the flexible RF cables at the output receivers of the IF
multiplexer board:
— 2-port models
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