User's Manual

Table Of Contents

DRAFT 1

TB9300 Installation and Operation Manual Replacing Modules 103

8.5 Replacing a Power Management Unit

Notice You must disconnect the AC and DC power cables before

removing the PMU from the subrack.

Removal 1. If you have not already done so, carry out the instructions in “Pre-

liminary Disassembly” on page 97.

2. At the front of the PMU, unplug and remove the output power

cable

b to the subrack interconnect board. Also unplug and remove

the system control bus cable

3. Unplug the output power cable to the PA

d and move it to one side.

4. Loosen the screws securing the retaining clamps

e and rotate the

clamps through 90° to clear the module.

5. Slide the PMU out of the subrack, taking care not to damage any of

the cables.

Refitting 1. Slide the replacement PMU into the subrack and secure it with the

retaining clamps.

2. Reconnect all the front and rear panel cables previously

disconnected. Connect the DC power cables on the rear panel as

shown in Figure 5.7 on page 81. Tighten the screws to a torque of

18–20lbf·in (2–2.25N·m). Ensure the front panel cables are

positioned correctly, and retained where required by the cable

retaining clips in the top of the subrack (refer to “Appendix B –

Inter-Module Connections” on page 111).

3. Carry out the instructions in “Final Reassembly” on page 106.

(obscured)