Troubleshooting the M320 Power System

To verify that a power supply is functioning normally, perform the following steps:

• Check the OUTPUT OK LED on each power supply faceplate (or the corresponding POWER OK LED on the craft interface). If this LED is on, the power source is good and the power supply is functional.
• Check the display on the craft interface. The Junos OS constantly updates the screen with status information for each component. For more information about the display, see M320 Craft Interface Description.

  Note: On the display and in the CLI, the power supplies are referred to as PEM0 through PEM3, from top to bottom.

If a power supply is not functioning normally, perform the following steps to diagnose and correct the problem:

• If the OUTPUT OK power supply LED is off, check the red alarm LED on the craft interface. The Junos OS monitors the system temperature, and if it exceeds a certain limit, the software triggers a red alarm, a condition that shuts down the power supplies.
• If a red alarm condition occurs, check the display on the craft interface to determine the source of the problem.

  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 assume the load, and you can still view the system status through the CLI or display.

• If the OUTPUT OK power supply LED is off and no red alarm condition exists, check that the circuit breaker on a DC power supply or the power switch on an AC power supply is switched to the on position (|).
• Verify that the source circuit breaker has the proper current rating. Each power supply must be connected to a separate source circuit breaker.
• Verify that the power cord (AC) or power cables (DC) from the power source to the router are not damaged. If the insulation is cracked or broken, immediately replace the cord or cable. See Replacing an M320 AC Power Supply Cord orReplacing an M320 DC Power Supply Cable.
• Connect the power supply to a different power source with a new power cord or power cables. If the power supply OUTPUT OK LED still does not light, the power supply is the source of the problem. Replace the power supply with a spare, as described in Replacing an M320 AC Power Supply or Replacing an M320 DC Power Supply.
• If the OUTPUT OK LED on the installed spare lights, the replaced power supply is faulty, and you should return it for replacement.
• If you cannot determine the cause of the problem or need additional assistance, see Contacting Customer Support.