Troubleshooting the M7i Power System When the LED on One M7i Power Supply Is Off

Problem

The LED on one power supply is off, but the LED on the other supplies indicate that they are functioning properly.

Solution

Perform the following diagnostic procedure:

1. Check the red alarm LED on the craft interface:
   • If it is lit, issue the following CLI command for information about the cause of an alarm condition:
     
     

     user@host> show chassis alarms

     For a list of messages that can appear in the output, see Overview of Troubleshooting Resources for the M7i Router.

     A common cause of power supply shutdown is that the temperature of the power supply or another router component has exceed the maximum limit.

   • If the red alarm LED is not lit, check that the power switch is in the ON position on the power supply faceplate.
2. Replace the faulty power supply with a spare. For instructions, see Replacing an M7i AC Power Supply and Replacing a DC Power Supply. If the LED lights correctly on the spare, the original power supply is faulty. Return it to Juniper Networks for replacement, as described in Contacting Customer Support.
3. If the spare power supply also does not work, connect the router to a different power source. You might also try replacing the AC power cord (on an AC-powered router) or DC power cables (on a DC-powered router). For instructions, see Replacing an AC Power Cord and Replacing an M7i DC Power Cable (you do not need to disconnect and reconnect the grounding cable).
4. If you cannot determine the cause of the problem or need additional assistance, see Contacting Customer Support.