Cisco Systems XR 12404 manual Troubleshooting an AC Power Subsystem

Chapter 4 Troubleshooting the Installation

Troubleshooting an AC Power Subsystem

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 power subsystem by first looking at the LEDs on the power supply. The INPUT OK LED on an AC PEM lights when AC power is applied; the OUTPUT OK LED lights when the PEM power switch is turned on.

Figure 4-1shows the location of the LEDs on the AC PEM (item 5).

Figure 4-1	AC PEM
1	2	3

INPUT	OUTPUT OUTP
OK			UT
	OK
		FAIL

65

INPUT 100-240V 12A

50/80HZ

66289

4

1	AC PEM handle	4	Power cord receptacle
2	On/Off switch	5	LEDs
3	Bail Latch	6	Captive screws

	Cisco XR 12404 Router Installation Guide
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