Router Installation Guide

Chapter 4 Troubleshooting the Installation

Troubleshooting an AC Power Subsystem

4-6

Cisco XR 12406 Router Installation Guide

OL-13831-01

Troubleshooting an AC Power Subsystem

AC PEMs provide –48 VDC OUTPUT. The +5 VDC OUTPUT from the CSF

powers the MBus module on each card in the system. The MBus module, in turn,

control the DC-DC converters also present on each card in the system. The

DC-DC converter takes –48 VDC from the power supply and converts it into +2.5,

+3.3 and +5 VDC, which is distributed to the card circuitry.

AC PEMs are monitored by the MBus module and the RP for over- or

undervoltage and over- or undercurrent conditions.

Begin checking the AC-input power subsystem by first looking at the LEDs on the

AC-input power supplies. Figure 4-1 shows the location of the LEDs on the power

supply.

Figure 4-1 AC-Input Power Supply LEDs

1 AC-input power supply 4 Captive screws on release levers

2 Handle 5 LEDs

3 Power standby switch – –

57916

2 5