Product Overview 1-53
Overview of the Cisco 12008
If the FAIL LED goes on, it indicates that one of the three SFCs in the lower card
cage has failed. To determine which of the SFCs has failed, you must remove the
air filter assembly and examine the status of the LEDs on each SFC.
Two side-by-side LEDS behind a vertical tab near the center of the SFC (see
Figure1-15) indicate the operational status of the card.
Figure1-15 Status LEDs on an SFC

Board Power and Fan Tray Power Functions of the CSC

DC-DC converters on the CSC provide power for its own circuitry, as well as power for the
fan trays. These functions are described briefly in the following sections.
•Board power—A DC-DC converter on the CSC takes the –48 VDC being delivered to
the card from the backplane and converts it into the +3.3 VDC required to drive the
card’s electronic circuity.
No redundancy is built into the CSC for the +3.3 VDC operating voltage; if the DC-DC
converter fails to deliver this voltage, the card shuts down, at which time the redundant
CSC, if installed, takes over to maintain normal system operations.
However, in a nonredundant CSC configuration, the failure of the installed CSC causes
the entire system to shut down.
H11366
Status LEDs
Left LED
(OK) Right LED
(FAIL)