Sun Microsystems SPARCcenter 2000 Service Manual page 40

2
Controlling Area Actions
AC distribution unit When the key switch is in the
position and the AC breaker on the AC
distribution unit is turned on, the disk drive
trays receive AC power.
Key Switch When the key switch is turned to the (On)
position, the DC power supply receives AC
current.
Control board The control board holds the system in reset
until all of the DC supplies reach nominal
operating voltages. Buffers on the control
board pass status signals from the power
supply and the main blower fan to the system
board(s).
System board The system board monitors the AC voltage,
the DC voltages, the DC blower fan rotation
speed, and the system board temperature
sensors. The system board can turn off the AC
distribution unit if the monitored conditions
cannot reach or stay within nominal ranges.
POST POST tests the system boards individually,
then POST tests the ability of system boards to
work together on the backplane.
POST does not test individual SBus cards,
drives, or interface cables.
POST next configures a system, omitting
marginal or failing circuits. The system uses
one of two possible schemes to assign the
system master. Refer to Section E.2, "System
Master Board" for specific information.
2-2
The third column shows how to verify the system is operating properly.
Table 2-1 Hardware and Software Control of the System
(Standby)
SPARCcenter 2000/2000E Service Manual—June 1996
Observations and Verification
Listen for the sound of the disk drives and
small AC fans in the drive trays.
Listen for the sound of the large DC blower
fan in the top of the system cabinet. The left
(green) front panel LED should light
immediately, indicating presence of DC power.
Four yellow LEDs on the left side of the
control board must be off. Four green LEDs on
the right of the control board must be on.
POST turns on the middle (yellow) front panel
LED while tests are running, and should turn
it off after about 60 seconds. The two green
LEDs should remain on.
Any other LED combination indicates a
problem. If all three LEDs are on, the problem
is not severe enough to prevent the system
from booting and running. If the right side
green LED remains off, the problem is major.
POST displays error messages on a terminal,
while displaying codes on the system board
LEDs (note: POST may reset the SuperSPARC
modules and the LED codes may be lost).