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    Replacing the Circuit Breaker Box on a DC-Powered M40e Router

    The circuit breaker box on a DC-powered router is field-replaceable, but you must power off the router before removing or replacing it.

    Removing the Circuit Breaker Box from a DC-Powered M40e Router

    The circuit breaker box on a DC-powered router is located on the rear of the chassis above the right power supply, as shown in M40e Chassis Description. It weighs about 6 lb (2.7 kg).

    Caution: Do not remove the grounding lug from the grounding points on the chassis during this procedure.

    To remove the circuit breaker box (see Figure 1):

    1. On the console or other management device connected to the master Routing Engine, enter CLI operational mode and issue the following command to shut down the router software. (If two Routing Engines are installed, also issue the command on the backup Routing Engine.)

      user@host> request system halt

      Wait until a message appears on the console confirming that the operating system has halted.

      For more information about the command, see the Junos System Basics and Services Command Reference.

      Note: The SFM might continue forwarding traffic for approximately 5 minutes after the request system halt command has been issued.

    2. For each power supply, press the power switch on the circuit breaker box 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 from both external power sources, 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. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to an M Series, MX Series, or T Series Router.
    5. Using a Phillips screwdriver, loosen and remove the screws securing the protective shield over the terminal studs on the circuit breaker box. Remove the cover.
    6. Using a 7/16-in. nut driver or wrench, loosen the outer nut securing the cable lug to each terminal stud. Remove the outer nuts and washers, leaving the inner nut and washer on each stud.
    7. Slide the cable lug off of each terminal stud. Leave the inner washer and nut on each stud.
    8. Remove the rear lower impeller assembly by loosening the thumbscrew at each corner and pulling the impeller assembly straight out of the chassis. For complete instructions, see Removing the M40e Rear Lower Impeller Assembly.
    9. Using a Phillips screwdriver, loosen and remove the screw at each corner of the circuit breaker box. Loosen the thumbscrews at the top and bottom edge of the box.
    10. Pull the circuit breaker box straight out of the chassis.

    Figure 1: Removing the Circuit Breaker Box

    Image g001262.gif

    Installing the Circuit Breaker Box in a DC-Powered M40e Router

    To install the circuit breaker box (see Figure 2):

    1. Verify that there is no power flowing from either 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. For each power supply, verify that the power switch on the circuit breaker box is in the OFF (O) position.
    3. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to an M Series, MX Series, or T Series Router.
    4. Align the guide pin on the back of the circuit breaker box with the opening in the chassis, then push the circuit breaker box straight in.
    5. Tighten the thumbscrews at the top and bottom edge of the circuit breaker box. Using a Phillips screwdriver, tighten the screw at each corner of the box.
    6. Slide the power cable lugs for both power sources onto the terminal studs on the circuit breaker box:
      • Connect the positive (+) source cable lugs to the return terminals on the circuit breaker box, which are labeled RTN(+).
      • Connect the negative (–) source cable lugs to the input terminals on the circuit breaker box, which are labeled –48V.
    7. Slide a washer and then screw a nut onto each terminal stud (if the washers and nuts were not installed on the studs, they should be in the accessory box). Using a 7/16-in. nut driver or wrench, tighten the nuts.
    8. Replace the protective shield on the circuit breaker box and tighten the screws that secure it to the box.
    9. Replace the rear lower impeller assembly by lining up the rails with the guides inside the chassis, pushing the impeller straight in, and tightening the thumbscrew at each corner of the impeller cover. For complete instructions, see Installing the M40e Rear Lower Impeller Assembly.
    10. Apply voltage from the DC power sources to the power cables so the router receives power.
    11. Press the switches on the circuit breaker box to the ON ( | ) position.
    12. Confirm that the LEDs on the power supply faceplates indicate correct operation: the green CB ON LED lights steadily, the blue OUTPUT OK LED blinks briefly, then lights steadily, and the yellow CB OFF LED does not light.

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

      If the system 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 system again, see Disconnecting AC Power from the M40e Router or Disconnecting DC Power from the M40e Router.

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

    Figure 2: Installing the Circuit Breaker Box

    Image g001261.gif

    Published: 2010-10-28