Juniper MX960 Hardware Manual page 677

Connect the power supply to a different power source with a new power cord or power cables. If the
power supply status LEDs indicate that the power supply is not operating normally, the power supply
is the source of the problem. Replace the power supply with a spare.
If all power supplies have failed, the system temperature might have exceeded the threshold, causing
the system to shut down.
NOTE: If the system temperature exceeds the threshold, the Junos OS shuts down all power
supplies so that no status is displayed.
The Junos OS also can shut down one of the power supplies for other reasons. In this case,
the remaining power supplies provide power to the router, and you can still view the system
status through the CLI or display.
To restart a high-capacity AC power supply after a shut down due to an over-temperature situation:
1. Move the power switch on the power supply to the off (o) position.
2. Turn off power to where the AC line goes into the power distribution module (PDM) area.
3. Wait for the power supply LEDs to fade out and for the fans inside the power supply to shutdown.
This can take up to 10 seconds.
4. Turn on power to where the AC line goes into the power distribution module (PDM) area.
5. Move the power switch on the power supply to the on (|) position.
6. Verify that the LEDs on the power supply faceplate are properly lit.
7. Issue the CLI show chassis environment pem command and verify the State is ONLINE and the
Temperature is OK.
To restart a high-capacity DC power supply after a shut down due to an over-temperature situation:
1. Switch off the circuit breaker(s) on the DC distribution panel to remove power to the chassis and
power supplies.
CAUTION: Do not attempt to power-on the power supply if the LED is still
lit and the fan is still running. If you do, the router will not reboot.
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