• Supported Platforms
• M120 Routers

• Related Topics
• M120 Power Supplies Description
• Replacing an M120 AC Power Supply
• Replacing an M120 DC Power Supply
• Troubleshooting the M120 Power System

Maintaining the M120 Power Supplies

Purpose

For optimum router performance, verify the condition of the power supplies.

Action

• Check the status of the power supplies by issuing the show chassis environment pem command. The output is similar to the following:
  
  

  user@host> show chassis environment pem

  PEM 0 status:
    State                           Online
    Temperature                     OK
    DC output                       OK
  PEM 1 status:
    State                           Online
    Temperature                     OK
    DC output                       OK

• Make sure that the power and grounding cables are arranged so that they do not obstruct access to other router components.
• Routinely check the OK and the STATUS OK LEDs on the power supply faceplates and the craft interface. If these output status LEDs are lit, the power supplies are functioning normally. For more information about the power supply LEDs, see M120 AC Power Supply LEDs and M120 DC Power Supply LEDs.
• Check the red and yellow alarm LEDs on the craft interface. Power supply failure or removal triggers an alarm that causes one or both of the LEDs to light. You can display the associated error messages by issuing the following CLI command:
  
  

  user@host> show chassis alarms

  For a list of possible alarm messages, see Chassis and Interface Alarm Messages.

• Periodically inspect the site to ensure that the grounding and power cables connected to the router are securely in place and that there is no moisture accumulating near the router. To review grounding and site wiring requirements for the router, seeDC Power Electrical Safety Guidelines for the M120 and Site Electrical Wiring Guidelines for M Series, MX Series, and T Series Routers.