Troubleshooting the Power Subsystem
Cisco 12008 Gigabit Switch Router Installation and Configuration Guide
5-10
Troubleshooting the Power Subsystem
The power subsystem in the Cisco 12008 consists of the following:
•AC-input or DC-input power supply(ies)
•MBus modules on the individual cards
•DC-DC converters on the individual cards
•Power distribution system in the Cisco12008 (see Figure 1-23)
Each power supply provides +5.2 VDC and –48 VDC output voltages to the backplane. The
+5.2 VDC output powers the MBus modules on each card in the system. The MBus
modules, in turn, control the DC-DC converters on each card. The DC-DC converter takes
the –48 VDC from the power supply and converts it into the various voltages required to
operate card circuitry.
To begin checking the power subsystem, examine the status of the two LEDs on the po wer
supply faceplate at initial system startup for the following conditions:
•The AC INPUT OK LED on the AC-input power supply or the INPUT OK LED on the
DC-input power supply goes on when the rotary power switch on the power supply
faceplate is turned on (|) and the unit is receiving source AC or DC power.
•The OUTPUT FAIL LED is normally off, but it goes on if the power supply output
voltage is not within tolerance.
In systems with a single AC-input power supply or a single DC-inp ut p o wer supp ly, and in
systems with redundant power when both power supplies are being shut down, the
OUTPUT FAIL LED goes on momentarily as the system shuts down, but goes off and
remains so when the power supply completely shuts down.
Each AC-input or DC-input power supply is monitored by i ts o wn onb oard MBu s modul e,
as well as by the master MBus module on the RP. Each power supply is monitored for
internal temperature conditions, overvoltage conditions, and overcurrent conditions.
Continue checking the power subsystem by assessing the following:
•Is the AC INPUT OK LED (AC-input power supply) or the INPUT OK LED (DC-input
power supply) on?
—If the answer is yes, source power is present and within tolerance; the power
supplies are functional.