• Supported Platforms
• T640 Routers

• Related Topics
• T640 Power System Description
• Replacing a T640 Two-Input 160-A DC Power Supply
• Replacing a T640 Three-Input 240-A DC Power Supply
• Replacing a T640 Four-Input 240-A DC Power Supply
• Replacing a T640 DC Power Supply Cable
• Replacing a T640 Three-Phase Delta AC Power Supply
• Replacing a T640 Three-Phase Delta AC Power Supply Cord
• Replacing a T640 Three-Phase Wye AC Power Supply
• Replacing a T640 Three-Phase Wye AC Power Supply Cord
• General Electrical Safety Guidelines and Electrical Codes for M Series, MX Series, and T Series Routers

Troubleshooting the T640 Power System

Problem

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.

• The following indicate a problem on a two-input 160-A DC power supply:

  • The DC OK and CB OK LEDs are off.
  • If the yellow CB TRIP LED lights but the power supply is not going through a startup test, the power supply detects a fault (the power supply fails, does not have sufficient airflow, or is not properly inserted).
  • The yellow OVER TEMP LED lights when the power supply is not receiving enough airflow to maintain proper temperature.

• The following indicate a problem on a three-input 240-A DC power supply or four-input 240-A DC power supply:

  • The blue DC OK LED is off.
  • If the blue DC OK LED blinks but is not going through a startup test, the power supply detects a fault (the power supply fails, does not have sufficient airflow, or is not properly inserted).
  • The yellow OVER TEMP LED lights when the power supply is not receiving enough airflow to maintain proper temperature.
  • The INPUT PRESENT LED is off, indicating that the input is not receiving source DC power.
  • If the INPUT PRESENT LED is lit but the CB ON LED is off, it indicates that the circuit breaker is off.

• The following indicate a problem on a three-phase delta or wye AC power supply:

  • The green AC OK LED is off when the power supply is not receiving source AC power.
  • The blue DC OK LED is off.
  • If the blue DC OK LED blinks but is not going through a startup test, the power supply detects a fault (the power supply fails, does not have sufficient airflow, or is not properly inserted).
  • The yellow OVER TEMP LED lights when the power supply is not receiving enough airflow to maintain proper temperature.

During normal operation:

• The blue DC OK LEDs light to indicate that the power supplies are functioning normally.
• The green CB ON and the blue DC OK LEDs on each two-input 160-A DC power supply faceplate are on, indicating that the power source is good and the power supplies are functional.

• For a three-input 240-A DC power supply or four-input 240-A DC power supply:

  • The green INPUT PRESENT and the blue DC OK LEDs are on, the power source is good and the power supplies are functional.
  • Each INPUT PRESENT LED is lit, indicating that the input is receiving source DC power.
  • The CB ON LED is lit, indicating that the circuit breaker is on.

• For a three-phase delta or wye AC power supply:

  • The green AC OK LED is lit, indicating that the power supply is receiving source AC power.
  • The blue DC OK LED is lit, indicating that the power supply is functioning normally.

Solution

To troubleshoot the T640 power system:

1. If the OVER TEMP LED on one of the power supplies lights, check the fans and air filters in the chassis to be sure they are functioning and providing sufficient airflow.
2. Check the display on the craft interface. The Junos OS constantly updates the screen with status information for each component. For more information about the display, see T640 Craft Interface Description.

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

   Note: If the system temperature exceeds the threshold, the Junos OS shuts down all power supplies so that no status is displayed on the craft interface. 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.

3. If a red alarm condition occurs, check the display on the craft interface to determine the source of the problem.
4. If the DC OK LED is not lit on one or both of the power supplies,
   • Check the power supply fans to see if they are operating.
   • 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 no red alarm condition exists, verify that the circuit breaker on the DC power supply or power switch on the AC power supply is switched to the on position (|).

5. Verify that the source circuit breaker is on and that the power supply is receiving voltage. If the AC OK on AC power supplies or INPUT PRESENT LEDs on a three-input 240-A DC power supply or four-input 240-A power DC supply are not lit, it indicates that the power supply is not receiving source power.
6. Verify that the source circuit breaker has the proper current rating. Each input on each power supply must be connected to a separate circuit breaker.
7. Verify that the AC power cord or DC power cables from the power source to the router are not damaged. If the insulation is cracked or broken, immediately replace the damaged cable or cord.
8. Connect the power supply to a different power source with a new DC power cable or AC power cord. 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.
9. If the DC OK LED on the installed spare lights, the replaced power supply is faulty. Return it for replacement, as described in T640 Return Procedure.
10. If you cannot determine the cause of the problem or need additional assistance, see Contacting Customer Support.