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23 Front Panel: Description/Voltages

This chapter describes the front panel.
Warnings and Cautions
Only a qualified service technician is authorized to remove the server covers and to access any
of the components inside the server. Before removing the covers, see “Safety Guidelines” on
page 115.

Front Panel Board

The front panel board provides the user interface to the server. Three push-button switches control
server power, reset, and NMI assertion. Four LEDs indicate power on, power supply failure, hard
drive failure, and fan or other server cooling failure. The LCD panel provides information about
the server such as boot status, available number of processors, and other server management
information.
The front panel board also allows other servers to communicate with this server—even while
power is down—via an external Intelligent Chassis Management Bus (ICMB). The ICMB is an
extension of the internal ICMB. A Phillips 80C652 microcontroller on the board controls all front
panel functions while AC power is available.
The board connects to the rest of the server through a connector on the CPU baseboard. All six
system fans plug into hot-plug connectors on the front panel board. The microcontroller controls
fan speed, monitors fan tachometer outputs, and indicates via LEDs—one for each fan—when fan
failures occur. The converter circuit converts 8.4 VDC to 12 VDC and provides over current
protection.