Replacing a DC Power Supply Cable

1. Removing a DC Power Supply Cable
2. Installing a DC Power Supply Cable

Removing a DC Power Supply Cable

1. Turn off the customer site circuit breaker that provides voltage to the DC power supply. 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. Follow your site's procedures.
2. Remove the power cable from external DC power source.
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 TX Matrix Plus Preventing Electrostatic Discharge Damage.
4. Switch the circuit breakers on the power supply faceplate to the off position (O).
5. Remove the input power tray from the power supply.
6. Use a Philips screwdriver to loosen the screws on the metal input power tray cover. Remove the metal input power tray cover.
7. Remove the cable restraint. Use a Phillips screwdriver.
8. Remove the nut and washer from the positive (+) DC power RTN (return) terminal on the upper row. Use a 7/16-in. (11 mm) nut driver (see Figure 1). Remove the cable lug from the terminal stud.

   Figure 1: Disconnecting DC Power Cables From the Positive Input Terminals

   
9. Remove the power lug separator over the terminal studs on the lower row of the input power tray.
10. Remove the nut and washer from the negative (–) DC power –48V (input) terminals on the lower row of the input power tray. Use a 7/16-in. (11 mm) nut driver (see Figure 2). Remove the cable lug from the terminal stud.

    Figure 2: Disconnecting DC Power Cables to the Negative Input Terminals

    
11. Carefully move the power cables out of the way.

Installing a DC Power Supply Cable

1. Locate a replacement power cable that meets the required specifications.

   Caution: A licensed electrician must attach a cable lug to the power cable that you supply. A cable with an incorrectly attached lug can damage the TX Matrix Plus router.

2. Slide the replacement power cable lug onto the terminal stud.
3. Secure the negative (–) DC source power cable lug to the –48V (input) terminal on the lower row (see Figure 3).

   Use a 7/16-in. (11 mm) nut driver or 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

   Caution: You must use an appropriate torque-controlled tool to tighten the nuts. Applying excessive torque damages the terminal studs and power supply. The maximum torque that may be applied to this nut is 25 in-lb (2.8 Nm).

   Caution: All inputs on the DC power supply in slot PEM0 must be powered by dedicated power feeds derived from feed A, and all inputs on the DC power supply in slot PEM1 must be powered by dedicated power feeds derived from feed B. This configuration provides the commonly deployed A/B feed redundancy for the system.

   Figure 3: Connecting DC Power Cables to the Negative Input Terminals

   
4. Replace the power lug separator over the lower terminal studs.
5. Secure the positive (+) DC source power cable lug to the RTN (return) terminal on the upper row, first with a washer, then with a nut (see Figure 4).

   Use a 7/16-in. (11 mm) nut driver or 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

   Caution: You must use an appropriate torque-controlled tool to tighten the nuts. Applying excessive torque damages the terminal studs and power supply. The maximum torque that may be applied to this nut is 25 in-lb (2.8 Nm).

   Figure 4: Connecting DC Power Cables to the Positive Input Terminals

   
6. Route the DC power cables through the cable restraints.
7. Attach the cable restraint to the input power tray.
8. Attach the input power tray cover.

   Figure 5: Attaching the Cable Restraint and Input Power Tray

   
9. Insert the input power tray into the power supply.
10. Verify that the power cabling is correct, that the power cables are not touching or blocking access to TX Matrix Plus components, and that they do not drape where people could trip on them.
11. Verify that the DC source power cabling is correct, that it is not touching or blocking access to TX Matrix Plus components, and that it does not drape where people could trip on them.
12. Attach the power cable to the external DC power source.
13. Switch on the customer site circuit breaker that provides voltage to the DC power source cable that has been replaced.
14. Verify that the INPUT PRESENT LED is lit steadily, indicating that the input is receiving power.
15. Switch the circuit breakers on the power supply to the on position (|).

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

16. Verify that the PWR ON LED on the power supply faceplate is lit steadily. The PWR ON LED blinks momentarily, then lights steadily to indicate that the circuit breakers are on.
17. Verify that the PEM OK LED on the power supply faceplate is lit steadily and that the FAULT LED is off, indicating that the power cable is correctly installed and the power supply is functioning normally.