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    Troubleshooting Power Supplies in an EX9208 Switch

    Problem

    The power system is not functioning normally.

    Cause

    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 glow steady green.
    • 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 must indicate that each of the power supplies is functioning normally:
      user@switch> show chassis environment pem
      PEM 0 status:
        State                      Online
        Temperature                OK
        DC Output           Voltage(V) Current(A)  Power(W)  Load(%)
                                48        12            576      36
      PEM 1 status:
        State                      Online
        Temperature                OK
        DC Output           Voltage(V) Current(A)  Power(W)  Load(%)
                                50        12            600      37
      

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

    • If a major 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, Junos OS shuts down all power supplies so that no status is displayed.

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

    • Check that the DC circuit breaker (—) or AC input switch (|) is in the on position and that the power supply 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 switch 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.

    Published: 2013-04-02