Cisco XR 12404 - Manual (Page 104)

Chapter 4 Troubleshooting the Installation
Troubleshooting an AC Power Subsystem
4-6
Cisco XR 12404 Router Installation Guide
OL-13830-02
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 4-1 shows the location of the LEDs on the AC PEM (item 5).
Figure 4-1 AC PEM
1 AC PEM handle 4 Power cord receptacle
2 On/Off switch 5 LEDs
3 Bail Latch 6 Captive screws
INPUT
OK OUTPUT
FAIL
INPUT
100-240V
12A
50/80HZ OUTPUT
OK
66289
4 5 6
1 2 3
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