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Troubleshooting the T4000 Power System

 

Problem:

Description:

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

  • If all power supplies have failed, the system temperature might have exceeded the threshold, causing the system to shut down.

  • Table 1 lists alarms for the power system, including the solution.

  • Table 2 lists abnormal LED states for the power supplies, including the solution.

Solution

  1. Check the display on the craft interface to determine the source of a yellow or red alarm (see Table 1). Junos OS constantly updates the screen with status information for each component. Note

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

    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 that case, the remaining power supply assumes the load, and you can still view the system status through the CLI or display.

  2. Issue the show chassis alarms command to check for power system alarms. See Table 1.
  3. Check the LEDs on each six-input DC power supply faceplate. See Table 2.
  4. Use the show chassis environment pem command.
    user@host> show chassis environment pem
  5. Verify that the customer site circuit breaker for each input has the proper current rating. Note

    All inputs on a DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and all inputs on a DC power supply in slot PEM1 must be powered by dedicated power feeds derived from feed B. This configuration provides the commonly deployed A/B feed redundancy for the system.

  6. Verify that the DC power cables from the power source to the router are not damaged. If the insulation is cracked or broken, immediately replace the DC power cable .
  7. Connect the power supply to a different power source with a new DC 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 still does not light—The replaced power supply might also be faulty. To return it for replacement, see Contacting Customer Support.
  8. If you cannot determine the cause of the problem or need additional assistance, see Contacting Customer Support.

In Table 1, 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: Power System Chassis Alarms

Alarm Type

LCD Message

CLI Message

Alarm Condition

Solution

Red

PEM pem-number High Temp

PEM pem-number High Temp

The power supply is not receiving enough airflow to maintain proper temperature.

Check that the power supply fans are running and that the air filters are clean to be sure they are functioning and providing sufficient airflow through the power supply.

If there is not sufficient airflow, replace the air filters.

Use the show chassis environment pem command to view the temperature.

PEM pem-number Input Fail

PEM pem-number Input Failure

A feed to the power supply has failed.

Check the input feed connectivity and voltage levels. Voltage range should be between –40 V and –72 V.

PEM pem-number Not OK

PEM pem-number Not OK

The power supply experienced a failure.

Replace the power supply.

PEM pem-number Improper

PEM pem-number Improper for Platform

The power supply is not supported.

Install a supported power supply.

Yellow

PEM pem-number Absent

PEM pem-number Absent

A power supply is not installed.

Install a supported power supply in the appropriate slot.

PEM pem-number Inputs Cfg

PEM pem-number Configuration Mismatch-number of inputs

The number of installed cables does not match the number of cables configured in the set chassis pem feeds command.

Ensure that the number of cables connected to the power supply is correct and that the number of cables connected matches the number of feeds configured on the router with the set chassis pem feeds command. Correct one or both of the following:

  • add or remove cables connected to the power supply

  • reconfigure the number of feeds and the input current by using the set chassis pem feeds and set chassis pem input-current commands

Table 2: Troubleshooting PDU LEDs

LED

Color

State

Condition

Solution

INPUT PRESENT

Green

Off

The input is not connected, not receiving voltage or is under –40 V.

  • Verify that the customer site circuit breakers are switched on. If the customer site circuit breakers are off, switch them on.

  • Verify that the input is receiving power within the supported voltage range.

    If the customer circuit breakers are switched on but the input is not receiving power, switch off the customer site circuit breakers, and reinstall the DC power source cables.

DC OK

Blue

Off

The power switch on the power supply faceplate is off, the power supply is not functioning normally, or the input voltage is not present or is under –40 V.

Verify that the customer site circuit breakers are switched on, and that the input is receiving power within the supported voltage range.

  • If the customer site circuit breakers are off, switch them on.

  • If the customer circuit breakers are switched on but the input is not receiving power, switch off the customer site circuit breakers, and reinstall the DC power source cables.

Blinking steadily

The input is okay, but the power supply might not be properly inserted, or there is a fault (such as insufficient airflow or faulty output).

The LED blinks when the power supply is initializing; but if it continues to blink, verify that the power supply is installed properly and that the power supply switch is in the on position.

If the LED continues to blink, replace the power supply.

OVER TEMP

Yellow

On

The power supply is shut down because of excessive internal tempature.

Check the power supply fan and air filters to be sure they are functioning and providing sufficient airflow through the power supply and that the power supply is operating within the specified ambient temperature.

Wait approximately 30 to 60 minutes and turn on the power supply. If the over temperature condition persists, replace the power supply.

Use the show chassis environment pem command to view the temperature.