Cisco Systems Cisco 12008 manual Board Power and Fan Tray Power Functions of the CSC

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 Figure 1-15) indicate the operational status of the card.

Figure 1-15 Status LEDs on an SFC

Left LED	Right LED
(OK)	(FAIL)
Status LEDs

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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.

Product Overview 1-53