Keysight N9038A MXE Service Guide 279
Front End Control
A15 Front End Control Assembly Troubleshooting
8. Verify that the status of the A9 Input Attenuator A LEDs on the Front End
Control Test board are as shown in Table 8-4 for the Mode Preset
instrument setting.
If the state of the status LEDs is correct proceed to the next step. If not,
there is most likely a problem with the A15 Front End Control assembly.
9. Turn the internal 50 MHz RF Calibrator signal on by pressing Input /
Output, RF Calibrator, 50 MHz.
10.Verify that the status of the A9 Input Attenuator A LEDs on the Front End
Control Test board are as shown in Table 8-4 for the RF Calibrator -
50 MHz instrument setting.
If the state of the status LEDs is correct proceed to the next step. If not,
there is most likely a problem with the A15 Front End Control assembly.
11.Change the RF Coupling to DC by pressing Input / Output, RF Input, RF
Coupling DC.
12.Verify that the status of the A9 Input Attenuator A LEDs on the Front End
Control Test board are as shown in Table 8-4 for the RF Coupling - DC
instrument setting.
If the state of the status LEDs is correct proceed to the next step. If not,
there is most likely a problem with the A15 Front End Control assembly.
13.Change the Mechanical Attenuator setting to 2 dB by pressing AMPTD,
Attenuation, Mech Atten, 2 dB.
14.Verify that the status of the A9 Input Attenuator A LEDs on the Front End
Control Test board are as shown in Table 8-4 for the Mechanical
Attenuator - 2 dB instrument setting.
If the state of the status LEDs is correct proceed to the next step. If not,
there is most likely a problem with the A15 Front End Control assembly.
Table 8-4 A9 Input Attenuator A Control Logic
Instrument Setting
Calibrator
Path
RF Input
AC
Selected
2 dB
Select A
2 dB
Select B
DC Select
+25V
Atten A
DS12 DS13 DS14 DS15 DS16 DS11 DS9
Mode Preset Off On On Off Off Off On
RF Calibrator - 50 MHz On Off On Off Off Off On
RF Coupling - DC On Off Off Off Off On On
Mechanical Attenuator - 2 dB On Off Off On Off On On
Mechanical Attenuator - 4 dB On Off Off On On On On
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