Verifying Power Supply Failure

To verify a power supply failure:

1. Check the Power Supply Power Switch
2. Check the Circuit Breaker
3. Perform a Power Supply Swap Test
4. Check the Router Cooling System
5. Test the Power Supply

Check the Power Supply Power Switch

Purpose

To verify power supply failure by checking the power supply power switch.

Action

If the OK power supply LED is off and no red alarm condition exists, check that the power switch is ON.

Check the Circuit Breaker

Purpose

To verify power supply failure by checking the circuit breaker.

Action

To check the circuit breaker:

1. Verify that the source DC or AC circuit breaker has the proper current rating. Each power supply in the router must be connected to a separate power source.
2. Make sure that the power switch is in the ON (|) position in the circuit breaker box for DC-powered routers. If the circuit breaker box has been tripped, reset it.

Perform a Power Supply Swap Test

Purpose

To verify a defective power supply by performing a swap test.

Action

To perform a power supply swap test, follow the procedure in the appropriate router hardware guide to remove the faulty power supply and connect it to a different source with a new power cable. If the power supply does not power on, then the power supply is the source of the problem. Return the faulty power supply for replacement, as described in the appropriate router hardware guide.

Caution: When replacing a power supply, do not leave a slot empty for more than two minutes while the router is operational. The power supply must remain in the chassis for proper airflow.

Warning: Do not touch the power connectors on the back side of the power supply. They can contain dangerous voltages.

Check the Router Cooling System

Purpose

The power supplies require an unobstructed airflow.

If the NO AIRFLOW LED on one of the power supplies lights, check that the airflow around the power supply is sufficient.

Action

To check the airflow, use the following command:

Sample Output

Class Item                   Status     Measurement
Power Power Supply A         OK
      Power Supply B         Absent

[...Output truncated...]
Fans  Top Impeller           OK         Spinning at normal speed
      Bottom Impeller        OK         Spinning at normal speed
      Rear Fan 1             OK         Spinning at normal speed
      Rear Fan 2             OK         Spinning at normal speed
      Rear Fan 3             OK         Spinning at normal speed

[...Output truncated...]

Meaning

The command output displays the power supply status and the cooling system status. When monitoring the power supplies, look at both the power supply status and the cooling system status. If the cooling system temperature is above a certain level, the power supplies are automatically cut off.

To check the power supply temperature on M40e and M160 routers, use the following command:

PEM 0 status:
  State                       Online
  Temperature                 OK
  DC input                    OK
  DC output                   OK
  Load                        Less than 20 percent
  Voltage:
    48.0 V input        69028 mV
    48.0 V fan supply   48839 mV
    5.0 V bias           5013 mV
    8.0 V bias           8253 mV
PEM 1 status:
  State                       Online
  Temperature                 OK
  DC input                    OK
  DC output                   OK
  Load                        Less than 20 percent
  Voltage:
    48.0 V input        69307 mV
    48.0 V fan supply   49170 mV
    5.0 V bias           4991 mV
    8.0 V bias           8263 mV

The command output displays the temperature of the air flowing past the power supplies (PEMs). The status is either OK or Failed.

To check the status of a specific power supply, indicate the slot number. For example, type show chassis environment pem slot, where slot can be either 0 or 1.

Test the Power Supply

Purpose

To verify power supply failure by testing the power supply.

Action

On certain power supplies (M5/M10, M40e, and M160 routers), a self-test button is used to test the power supply, It is located beneath the power supply LEDs.

Tip: The self-test button is for use by qualified service personnel only