Replacing an M320 DC Power Supply

1. Removing an M320 DC Power Supply
2. Installing an M320 DC Power Supply

Removing an M320 DC Power Supply

The power supplies are located at the rear of the chassis below the SIBs. Each power supply weighs approximately 10 lb (4.5 kg).

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

To remove a DC power supply:

1. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during the removal process.
2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
3. Switch the circuit breaker on the DC power supply faceplate to the off position (O).
4. Remove the clear plastic cover protecting the terminal studs on the faceplate.
5. Remove the nuts and washers from the terminal studs (see Figure 1). (Use a 7/16-in. (11 mm) nut driver.)

   Figure 1: Disconnecting Power Cables from the DC Power Supply

   
6. Remove the cable lugs from the terminal studs.
7. Loosen the captive screws on the cable restraints on the right edge of the power supply faceplate.
8. Carefully move the power cables out of the way.
9. Loosen the captive screw on each side of the power supply faceplate completely.
10. Twist the ejector handles on the upper corners of the faceplate counterclockwise to unseat the power supply.
11. Pull firmly to start removing the power supply. Slide it halfway out of the chassis (see Figure 2).

    Warning: Do not touch the power connectors on the rear of the power supply (see Removing an M320 AC Power Supply). They can contain dangerous voltages.

12. Place one hand underneath the power supply to support it, and slide it completely out of the chassis.

    Caution: Each power supply weighs approximately 10 lb (4.5 kg). Be prepared to support the full weight of the power supply as you remove it from the router.

Figure 2: Removing a DC Power Supply

Installing an M320 DC Power Supply

To install a DC power supply (see Figure 3):

1. Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during installation.

   Caution: You must ensure that power connections maintain the proper polarity. The power source cables might be labeled (+) and (–) to indicate their polarity. There is no standard color coding for DC power cables. The color coding used by the external DC power source at your site determines the color coding for the leads on the power cables that attach to the terminal studs on each power supply.

2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
3. Switch the circuit breaker on the DC power supply faceplate to the off position (O).
4. Using both hands, slide the power supply into the chassis until you feel resistance.
5. Firmly push the power supply into the chassis until it comes to a stop. The power supply faceplate should be flush with any adjacent power supply faceplates.
6. Tighten the captive screws on each side of the power supply faceplate to secure the power supply in the chassis.
7. Remove the clear plastic cover protecting the terminal studs on the faceplate.
8. Remove the nuts and washers from the terminal studs.
9. Attach the lugs on the DC source power cables to the terminal studs.
   1. Attach the lugs on the positive (+) DC source power cables to the terminal studs.
   2. Attach the lugs on the negative (–) DC source power cables to the terminal studs.

   Secure each cable lug to the terminal stud, first with a washer, then with a nut. Use a 7/16-in. (11 mm) nut driver or socket wrench to tighten the nut. Apply between 23 lb-in. (2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each nut.

   Note: The DC power supplies in slots PEM0 and PEM1 must be powered by dedicated power feeds derived from feed A, and the DC power supplies in slots PEM2 and PEM3 must be powered by dedicated power feeds derived from feed B. This configuration provides the commonly deployed A/B feed redundancy for the system.

10. Loosen the captive screw on the cable restraint on the right edge of the power supply faceplate.
11. Route the positive and negative DC power cables through the top and bottom of the cable restraint.
12. Tighten the cable restraint captive screw to hold the power cables in place.
13. Verify that the ground and power cabling are correct, that they are not touching or blocking access to router components, and that they do not drape where people could trip on them.
14. Replace the clear plastic cover over the terminal studs on the faceplate.
15. Switch on the external circuit breakers to provide voltage to the DC power source cable leads.
16. Switch the circuit breaker on the power supply faceplate to the on position (|). Verify that the OUTPUT OK status LED on the power supply faceplate blinks, then lights steadily approximately 1 minute after you switch the power supply circuit breaker on.

Figure 3: Installing a DC Power Supply

Figure 4: Connecting Power Cables to the DC Power Supply