Keysight N9038A Service Guide

282 Keysight N9038A MXE Service Guide
Front End Control
A15 Front End Control Assembly Troubleshooting
Verifying the Control for the A10 Input Attenuator B
1. Remove the instrument dress cover (MP24) and top brace (MP10). Refer to
Chapter 18, “Assembly Replacement Procedures.” for instructions on
removing these covers.
2. Disconnect cable W3 from J801 as shown in Figure 8-6.
3. Connect the A9 / A10 Input Attenuator Control cable from J801 to the
Front End Control Test board J3 & J4 as shown in Figure 8-3.
4. Place the Front End Control Test board on a non-conductive surface.
5. Turn the instrument on and allow it to complete its boot up process,
ignoring any alignment failures.
6. Turn the instrument auto alignment routine off by pressing System,
Alignments, Auto Align, Off.
7. Tune the instrument to a Center Frequency of 50 MHz with a Span of 0 Hz
by pressing FREQ, 50 MHz and SPAN, Zero Span.
8. Verify that the status of the A10 Input Attenuator B LEDs on the Front End
Control Test board are as shown in Table 8-5 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.
The 10 pin connector of the A9 / A10 Input Attenuator Control cable with the RED stripe on the
cable goes to J3 on the Front End Control Test board.
Table 8-5 A10 Input Attenuator B Control Logic
Instrument Setting
10 dB Step
6 dB Step
20 dB Step 30 dB Step
+25V
Atten B
DS18 DS17 DS19 DS20 DS10
Mode Preset On Off Off Off On
Mechanical Attenuator - 6 dB Off On Off Off On
Mechanical Attenuator - 10 dB On Off Off Off On
Mechanical Attenuator - 20 dB Off Off On Off On
Mechanical Attenuator - 30 dB Off Off Off On On
Mechanical Attenuator - 66 dB On On On On On

Keysight N9038A Specifications

General

Brand	Keysight
Model	N9038A
Category	Measuring Instruments
Language	English