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    Maintaining M40e Power Supplies



    To verify that the power system is functioning normally, regularly:

    • Check the LEDs on the faceplate of both power supplies:
      • An AC power supply is functioning correctly when the green LED labeled OUTPUT OK is lit steadily.
      • A DC power supply is functioning correctly when the green LED labeled CB ON is lit steadily (indicating that the circuit breaker is switched on) and the blue LED labeled OUTPUT OK is lit steadily (indicating that the supply is receiving power from the DC source).

      If these LEDs are blinking or other LEDs are lit, there could be an error condition. For a summary of LED states, see M40e Power System Description.

    • Issue the following CLI command to check the status of the power supplies. The following example specifies a slot number (0), which is optional. As shown in the sample output, the value Online in the State column indicates that the power supply is operating normally:

      user@host> show chassis environment pem 0
      PEM 0 status:
        State                           Online
        Temperature                     OK
        DC input                        OK
        DC Output                       OK
        Load                            Less than 40 percent
          48.0 V input            55059 mV
          48.0 V fan supply       50181 mV
          5.0 V bias               5032 mV
          8.0 V bias               8224 mV

      Note: The messages in the craft interface LCD and the output from CLI show commands refer to the power supply on the right as PEM 0 and the power supply on the left as PEM 1.

      For further description of the output from the command, see the Junos OS System Basics and Services Command Reference.

    • Check the red and yellow alarm LEDs and the LCD on the craft interface. Power supply failure or removal triggers an alarm that causes one or both of the LEDs to light and an error message to appear on the LCD. You can display the associated error messages by issuing the CLI command:

      user@host> show chassis alarms

      For a list of possible alarm messages, see M40e Chassis and Interface Alarm Messages .

    • Verify that the power source has the proper current rating and that each power supply is connected to a separate power source.
    • Verify that the cable or cord connecting the power supply to the external power source is securely in place and that there is no moisture accumulating near the router.
    • Verify that the cable or cord from the power source to the router is not damaged. If the insulation is cracked or broken, replace the cable or cord immediately.
    • Verify that the power cables or cord do not touch or obstruct access to other router components, and that they do not drape where people could trip on them.
    • Verify that the air flow in and out of cooling system components is not obstructed.

    Published: 2010-10-28