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Replacing a DC Power Supply

 

A DC-powered router has one or two load-sharing, redundant DC power supplies that install into the rear of the router as shown in M7i Chassis Description. Each power supply is hot-removable and hot-insertable, as described in M7i Field-Replaceable Units (FRUs). When one power supply fails or is powered down, the remaining power supplies automatically assume the entire electrical load for the router. For more information about DC power supplies, see M7i DC Power Supply.

To replace a DC power supply, perform the following procedures:

Removing a DC Power Supply

Before removing a DC power supply from an M7i router with only one power supply, you must power off the router. See Powering Off the M7i Router. The DC power supplies are located at the bottom rear of the chassis, as shown in M7i Chassis Description. Each DC power supply weighs approximately 7 lb (3.2 kg).

Caution

Do not leave a power supply slot empty for more than a short time while the router is operational. The power supply must remain in the chassis for proper airflow.

To remove a DC power supply (see Figure 1):

  1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. Verify that the router is attached to a proper earth ground.
  2. Press the power switch for the power supply (located on the power supply faceplate) to the OFF (O) position.Note

    If you are power cycling the power supply rather than shutting it off for a time, wait at least 60 seconds after turning it off before turning it back on. If you need to power it off again, wait for at least 60 seconds after powering it on.

  3. Shut off the power flowing to the power supply from the external power source, so that the voltage across the leads of the power cables is 0 V. Ensure that there is no chance that the cable leads might become active during the procedure.
  4. Using a number 1 Phillips screwdriver, turn the screw on each field-wiring terminal counter-clockwise to loosen the terminal connector from around the cable lug.
  5. Remove the cables from the terminal connectors and from the hook located on the faceplate to the right of the field-wiring terminals.
  6. Loosen the thumbscrew at each corner of the power supply faceplate, using a Phillips screwdriver if necessary.
  7. Grasp the handle on the power supply faceplate and pull firmly to slide the unit about halfway out of the chassis.
  8. Place one hand under the power supply to support it, then slide it completely out of the chassis.
Figure 1: Removing a DC Power Supply
Removing a
DC Power Supply

Installing a DC Power Supply

To install a DC power supply (see Figure 2):

  1. Verify that there is no power flowing to the power supply from the external power source, so that the voltage across the leads of the power cables is 0 V. Ensure that there is no chance that the cable leads might become active during the procedure.
  2. Verify that the power switch for the power supply (located on the power supply faceplate) is in the OFF (O) position.
  3. Verify that the grounding cable is attached to the chassis and properly connected to an earth ground.
  4. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. Verify that the router is attached to a proper earth ground.
  5. Place one hand under the power supply and grasp the handle on the faceplate with the other hand. Slide the power supply into the chassis until it contacts the midplane.
  6. Starting with the bottom screw, tighten (but do not overtighten) the thumbscrews at each corner of the power supply faceplate.
  7. Verify that a licensed electrician has attached a listed power cable lug to each power source cable.
  8. Loop the power cables through the hook located on the faceplate to the right of the field-wiring terminals.
  9. Depending on the type of power cable lugs used, loosen or remove the screws on the field-wiring terminals.
  10. Insert the power cable lugs into the appropriate field-wiring terminals. Using a number 1 Phillips screwdriver, turn the screw on each field-wiring terminal clockwise to secure the power cable lug. Apply between 8 lb-in. (.9 Nm) and 9 lb-in. (1.02 Nm) of torque to each screw.
    1. Insert the positive (+) source cable into the return terminal, which is labeled RTN.
    2. Insert the negative (–) source cable into the input terminal, which is labeled –48V.
  11. Verify that the DC source power cabling cabling is correct, that the DC power cables are not touching or blocking access to router components, and that they do not drape where people could trip on them.
  12. Turn on the DC power source so that voltage flows to the power supply.
  13. Press the switch on the power supply faceplate to the ON ( | ) position. Note

    After powering on a power supply, wait at least 60 seconds before turning it off.

  14. If the M7I has only one power supply or the router is completely powered off when you power on the power supply, the Routing Engine boots as the power supply completes its startup sequence. If the Routing Engine finishes booting and you need to power off the router again, see Powering Off the M7i Router. Note

    After powering off a power supply, wait at least 60 seconds before turning it back on.

  15. Check the LEDs on the power supply faceplate. When the power supply has powered on successfully, the green OUTPUT OK LED lights steadily.

    After a power supply is powered on, it can take up to 60 seconds for status indicators—such as the output status LED on the power supply, the command display output, and messages on the LED display on the craft interface—to indicate that the power supply is functioning normally. Ignore error indicators that appear during the first 60 seconds.

Figure 2: Installing a DC Power Supply
Installing
a DC Power Supply