Input Attenuator B Control Logic Verification; Low Band Switch Control Logic Verification; (All Except Option 503) - Keysight n9020a Service Manual

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
5-5
board according to
Table 5-5 Input Attenuator B LED's
Attenuator
Setting (dB)
6
10
16
20
30
40
50
60
66
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, 2 MHz 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
5-6.
Table 5-6
and verify the proper LED's illuminate on the Front End Troubleshooting
Table 5-5.
DS20
30 dB
Step LED
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
Test Board
Test Point
In1A
DS19 DS18
20 dB 10 dB
Step LED Step LED
OFF OFF
OFF ON
OFF ON
ON OFF
OFF OFF
OFF ON
ON OFF
ON ON
ON ON
Vol tage
(VDC)
−9.90
216
Table
DS17
6 dB
Step LED
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
ON
Table