Keysight N9020A - Input Attenuator B Control Logic Verification; Low Band Switch Control Logic Verification; (All Except Option 503)

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Front End Control Troubleshooting
A15 Front End Control Assembly Troubleshooting
Input Attenuator B Control Logic Verification
Press AMPTD, Attenuation 6 dB on the analyzer and verify the 6 dB Step LED
DS17 is illuminated. Change to the input attenuation settings found in Table
5-5 and verify the proper LED's illuminate on the Front End Troubleshooting
board according to Table 5-5.
If the LED's illuminate correctly, the switch control logic for the input
attenuators from the A15 Front End Control Assembly is correct. If the LED's
are not illuminating as expected, the most probable cause is the A15 Front End
Control Assembly.
Set the input attenuator back to 10 dB by pressing AMPTD, Attenuation, 10 dB
on the analyzer.
Low Band Switch Control Logic Verification
(all except Option 503)
Press Mode Preset on the analyzer. Press FREQ, 50 MHz, SPAN, 2MHz on the
analyzer. Make sure the auto alignments are turned off by pressing System,
Alignments, Auto Align, Off. Connect the voltmeter positive lead to test point
listed in the table below and the negative lead to the instrument chassis. These
test points are located under the J2 connector. Verify the voltages in Table
5-6.
Table 5-5 Input Attenuator B LED’s
Attenuator
Setting (dB)
DS20
30 dB
Step LED
DS19
20 dB
Step LED
DS18
10 dB
Step LED
DS17
6 dB
Step LED
6 OFF OFF OFF ON
10 OFF OFF ON OFF
16 OFF OFF ON ON
20 OFF ON OFF OFF
30 ON OFF OFF OFF
40 ON OFF ON OFF
50 ON ON OFF OFF
60 ON ON ON OFF
66 ON ON ON ON
Table 5-6
Test Board
Test Point
Voltage
(VDC)
In1A −9.90