Troubleshooting the TX Matrix Plus Power System

Problem

• The blue PEM OK LED on each power supply is on steadily, indicating that the power source is good and the power supplies are functional.
• The CB ON LEDs is on steadily indicating that the circuit breaker on the power supply is on.
• The INPUT PRESENT LEDs lights green indicating that the input is receiving source DC power.
• The green PEM OK LEDs on the craft interface are on steadily, indicating that the power supplies are functional.
• The red PEM FAIL LEDs on the craft interface are off, indicating no faults have been detected on the power supplies.

• The power supplies are automatically shut down.

  Note: 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 the system shuts down both power supplies, no status is displayed on the craft interface.

• An alarm indicates that the temperature of the power supply exceeds the maximum (“temperature hot”) threshold.
• An alarm indicates that a power supply has been removed.
• An alarm indicates that the power input or output has failed.
• The PEM OK LED on the power supply is off.
• The yellow FLT LED on the power supply is lit indicating that the power supply detects a fault.
• A green PEM OK LED on the craft interface is off, indicating that the power supply is not functional.
• The red PEM FAIL LEDs on the craft interface is on, indicating that a fault has been detected on the power supply.

Solution

1. Check the LEDs on each seven-input 420-A power supply faceplate.
   • PEM OK power supply LED is off—Determine if there is a red alarm LED on the craft interface.
   • PEM OK power supply LED is off but no red alarm condition exists—Verify that INPUT PRESENT LEDs are lit steadily green and that the PWR ON LEDs are lit indicating that the circuit breakers are switched to the on position (|).
   • FLT LED on a power supplies is lit— the power supply has failed, does not have sufficient airflow to maintain proper temperature, or is not properly seated in the chassis. It might also indicate that the power supply is going through a startup test
     • Verify that the fan trays and air filters in the chassis are functioning and providing sufficient airflow through the chassis.
     • Verify that the power supply is properly seated in the chassis.
2. Check the LEDs on the craft interface:
   • Verify that the PEMS OK is lit and that the FAIL LED is not lit.
   • 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 left to right.

3. Issue the show chassis environment pem sfc 0 to verify that the power supplies are Online, DC Input is OK, and the DC output for each channel on each PEM are equal.

   Note: The current sharing between PEMs relies on equal voltages at the input terminals of the PEMs. The TX Matrix Plus router system power is divided into multiple load zones. The input voltage on each input should match the voltage on the same input on the other power supply. However, if the voltages do not match, the TX Matrix Plus router operates normally as long as the DC input voltages are within the operating range.

   user@host> show chassis environment pem sfc 0

   sfc0-re0:
   --------------------------------------------------------------------------
   PEM 0 status:
     State                      Online
     Temperature                35 degrees C / 95 degrees F             
     DC Input:                   OK
     DC Output             Voltage   Current       Power    Load
         Channel 0           53820     14140         761      59     
         Channel 1           53550     12720         681      53     
         Channel 2           53840     12930         696      54     
         Channel 3           53690     14990         804      63     
         Channel 4           53620     15070         808      63     
         Channel 5           53900     14820         798      62     
         Channel 6           54120     5020          271      21  
   
   PEM 1 status:
     State                      Online
     Temperature                35 degrees C / 95 degrees F             
     DC Input:                   OK
     DC Output             Voltage   Current       Power    Load
         Channel 0           53820     14140         761      59     
         Channel 1           53550     12720         681      53     
         Channel 2           53840     12930         696      54     
         Channel 3           53690     14990         804      63     
         Channel 4           53620     15070         808      63     
         Channel 5           53900     14820         798      62     
         Channel 6           54120     5020          271      21  

4. Issue the show chassis alarms command to check for alarms. See Table 1
5. Verify that the source circuit breaker has the proper current rating.

   Note: All inputs on the DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and all inputs on the 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 power cables from the power source to the TX Matrix Plus router are not damaged. If the insulation is cracked or broken, immediately replace the cable.
7. Connect the power supply to a different power source with a new power cable. If the power supply PEM OK LED still does not light, the power supply is the source of the problem.
8. Replace the power supply with a spare. If the PEM OK LED on an installed spare lights, the power supply that was replaced is faulty, and you should return it for replacement.
9. If you cannot determine the cause of the problem or need additional assistance, contact JTAC for assistance.

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.