• Supported Platforms
• MX240 Routers

• Related Topics
• MX240 AC Power Supply Description
• MX240 DC Power Supply Description
• Troubleshooting Resources for MX240 Routers
• Replacing an MX240 AC Power Supply
• Replacing an MX240 DC Power Supply

Troubleshooting the MX240 Power System

Problem

The power system is not functioning normally.

Solution

• Check the LEDs on each power supply faceplate.
  • If an AC power supply is correctly installed and functioning normally, the AC OK and DC OK LEDs light steadily, and the PS FAIL LED is not lit.
  • If a DC power supply is correctly installed and functioning normally, the PWR OK, BRKR ON, and INPUT OK LEDs light green steadily.
• Issue the CLI show chassis environment pem command to check the status of installed power supplies. As shown in the sample output, the value Online in the rows labeled State indicates that each of the power supplies is functioning normally:
  
  

  user@host> show chassis environment pem

  PEM 0 status:
    State                           Online
    Temperature                     OK
    DC output                       OK
  PEM 2 status:
    State                           Online
    Temperature                     OK
    DC output                       OK

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

• If a red alarm condition occurs, issue the show chassis alarms command to determine the source of the problem.
• 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.

• Check that the AC input switch ( | ) or DC circuit breaker (—) is in the on position and is receiving power.
• 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 AC power cord or DC power cables from the power source to the router are not damaged. If the insulation is cracked or broken, immediately replace the cord or cable.
• 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.