Cisco GSR12/60 - 12012 Router -AnyLAN, SONET/SDH Installation And Configuration Manual page 215

For the troubleshooting procedures in this chapter, the Cisco 12012 consists of the
following subsystems:
•
Power subsystem—consists of the following components:
— AC-input power supplies or DC-input power supplies. The Cisco 12012 can be
configured for source AC power or source DC power. A minimally configured
Cisco 12012 system operating with source AC power has two AC-input power
supplies installed. Adding a third and fourth AC-input power supply provides
power supply redundancy and current sharing among the power supplies.
A Cisco 12012 system operating with source DC power has one DC-input power
supply installed. Adding a second DC-input power supply provides power supply
redundancy and current sharing between the power supplies.
Caution Do not mix AC-input power supplies and DC-input power supplies in a
Cisco 12012.
— DC-DC converters. A DC-DC converter is installed on each card in the upper and
lower card cages. The converter is under control of the MBus module, another
component on each card. The DC-DC converter takes –48 VDC and converts it into
+3.3 VDC and +5 VDC for use by the card circuitry.
— Harnesses. Two harnesses link the backplane with the two blower modules.
•
Cooling subsystem—comprises the two blower modules, which includes the individual
blowers, the blower speed control card, the faceplate LEDs, and the air filter. The two
blower modules should be operating whenever the system power is on.
The variable speed feature in the Cisco 12012 allows a blower to operate at a slower
speed and provide quieter operation when the internal system temperature is within the
normal operating range. If the internal temperature exceeds a specific temperature, the
blower speed increases to move more cooling air through the system. As a result, it
might be difficult to determine whether or not the blower is operating in noisy,
air-conditioned rooms. If you determine that the blower is not operating, contact a
service representative immediately; there are no installation adjustments that you can
make.
Troubleshooting Overview
Troubleshooting the Installation 5-3