Keysight N9040B Option 508 Service Manual page 53

Boot Up and Initialization Troubleshooting
Potential Problems During Boot Process
Is the +5.1V_STBY LED on the A7 Midplane board on?
If yes:
If not:
Before replacing the power supply, verify the midplane and motherboard interconnects are
mechanically secure.
Keysight Technologies N9040B UXA Signal Analyzer Service Guide
After verifying that the connections from the yellow front panel Standby
LED back to the A4 Processor board are not at fault, replace the A4
Processor board.
Replace the A6 Power Supply assembly.
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