Keysight E4990A Troubleshooting Manual page 27

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Troubleshooting
26
Step 4.
Check the external monitor
Connect an external VGA monitor to the External Monitor Output
Port on the E4990A rear panel.
• If something is displayed on the external monitor, the
problem seems to be related to the LCD display. Also, check
the A52 Front Panel I/F board because the ON/OFF setting of
the LCD backlight is controlled by the A52 Front Panel I/F
board.
• If nothing is displayed even on the external monitor, the
problems seems to be in the A60 CPU module.
Step 5.
Check the flat cable
Check the flat cable between the A60 CPU Module and A52 Front
Panel I/F board.
Step 6.
Check around the backlight
Check the inverter board and the cable between the inverter board
and A52 Front Panel I/F board. Also check the cables between the
LCD and A52 Front Panel I/F board. If the cables are normal, check
the LCD display.
Impedance Analyzer