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Troubleshooting the TX Matrix Power System

 

Problem:

Description:

The following alarms, LEDs, command output, and conditions indicate a problem with the power system:

  • The yellow CB TRIP LED lights on the two-input 160-A power supply faceplate to indicate that the power supply detects a fault (the power supply fails, does not have sufficient airflow, is going through a startup test, or is not properly inserted).

  • The blue DC OK LED blinks on the three-input 240-A power supply faceplate to indicate that the power supply detects a fault (the power supply fails, does not have sufficient airflow, is going through a startup test, or is not properly inserted).

  • The yellow OVER TEMP LED lights on the power supply faceplate when the two-input 160-A power supply or the three-input 240-A power supply is not receiving enough airflow to maintain proper temperature.

Solution

To verify that a power supply is functioning normally:

  • Check the LEDs on each two-input 160-A power supply faceplate.

    • If the green CB ON and the blue DC OK LEDs are on, the power source is good and the power supplies are functional.

    • The CB ON LED on the power supply lights when the circuit breaker is functioning.

    • The DC OK LED lights when the power supply is receiving source DC power.

    • The yellow CB TRIP LED lights when the power supply detects a fault (the power supply fails, does not have sufficient airflow, is going through a startup test, or is not properly inserted).

    • The yellow OVER TEMP LED lights when the power supply is not receiving enough airflow to maintain proper temperature.

  • Check the LEDs on each three-input 240-A power supply faceplate.

    • If the green INPUT PRESENT and the blue DC OK LEDs are on, the power source is good and the power supplies are functional.

    • The INPUT PRESENT LED lights when the input is receiving source DC power.

    • The CB ON LED on the power supply lights when the circuit breaker is on.

    • The blue DC OK LED blinks when the power supply detects a fault (the power supply fails, does not have sufficient airflow, is going through a startup test, or is not properly inserted).

    • The yellow OVER TEMP LED lights when the power supply is not receiving enough airflow to maintain proper temperature.

  • Check the display on the craft interface. The Junos OS constantly updates the screen with status information for each component.

    Red alarm or yellow alarm LED is lit—Use the show chassis alarms command to determine the source of the problem. The Junos OS constantly updates the screen with status information for each component. See Table 1 for a description of power supply alarms and how to recover from alarm conditions.

    Note

    On the display and in the CLI, the power supplies are referred to as PEM0 and PEM1, from top to bottom.

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

  • If the DC 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 supply assumes the load, and you can still view the system status through the CLI or display.

  • If the DC OK power supply LED is off and no red alarm condition exists, check that the circuit breaker is switched to the on position (|).

  • Verify that the source circuit breaker has the proper current rating. Each input on each power supply must be connected to a separate power source.

  • Verify that the power cables from the power source to the TX Matrix router are not damaged. If the insulation is cracked or broken, immediately replace the cable.

  • Connect the power supply to a different power source with a new power cable. If the power supply DC OK LED still does not light, the power supply is the source of the problem. Replace the power supply with a spare.

  • If the DC OK LED on the installed spare lights, the replaced power supply is faulty, and you should return it for replacement, as described in Returning a Hardware Component to Juniper Networks, Inc..

  • If the OVER TEMP LED on one of the power supplies lights, check the fans and air filters to be sure they are functioning and providing sufficient airflow through the chassis.

  • Issue the show chassis environment pem command to check the status of the power supplies. The output is similar to the following:

    user@host> show chassis environment pem scc
    Note

    If 0 is displayed for the SCG/CB/SIB in the Current, Power, and Load fields for a PEM, and the voltage field does not match the other PEM, it might indicate a difference between the DC input voltages applied to PEM0 and PEM1. Consider checking your DC power network for unintended voltage drops to the TX Matrix router.

    The current sharing between PEMs relies on equal voltages at the input terminals of the PEMs. The TX Matrix router system power is divided into two load zones, one load zone consists of INPUT 0 of PEM0 and PEM1, while the other load zone consists of INPUT 1 of PEM0 and PEM1. Load sharing will occur only between the PEMs of each load zone (INPUT 0 or INPUT 1); therefore, those two PEMs voltages are the ones that should be equal for current sharing. However, if the voltages do not match, the TX Matrix router operates normally as long as the DC input voltages are within the operating range.

  • If you cannot determine the cause of the problem or need additional assistance, see Contacting Customer Support.

The text in the column labeled ”LCD Message” appears in the display of the craft interface. The text in the column labeled “CLI Message” appears in the output from the show chassis alarms command.

Table 1: TX Matrix Chassis Power Supply Alarm Messages

Alarm Type

LCD Message

CLI Message

Red

PEM pem-number Over Temp

PEM pem-number Over Temperature

PEM pem-number Output Fail

PEM pem-number Output Failure

PEM pem-number Input Fail

PEM pem-number Input Failure

Yellow

PEM pem-number Removed

PEM pem-number Removed