Technical data

6-14
Chassis Operations
6
Several conditions can trigger the alarm:
❏ A failed fan in a warm environment
❏ Blocked airflow in or out of the enclosure
❏ An ambient temperature near the specified limits of the
enclosure (50˚ C/122˚ F)
The overtemperature LED turns off when the cooling problem is
corrected if the correction is made before the power supply sensor
warms another 5˚ F to system shutdown. Powering down to correct
a problem may not be necessary, because many failures are caused
by nothing more than inadvertent blockages of the airflow. Prompt
removal of a blockage allows recovery without a shutdown of
system power. In general, power should not be removed from the
system until a normal system shutdown is completed.
SCSI Enclosure
The power supply in the SCSI peripheral expansion enclosure is
monitored in the same way as that of the main chassis. A heat
buildup beyond the first threshold within a monitored SCSI
enclosure illuminates the warning LED.
If temperatures climb further, however, no power shutdown
occurs.
Voltage Monitoring Function
Overvoltage protection circuitry monitors the power supply inputs
and outputs. If the power inputs of a monitored power supply go
out of range, or if the +5Vdc output strays out of tolerance and
remains so, the power supply of the affected chassis is shut down
automatically.
The voltage monitoring function is confined to the system itself; it
does not extend to the SCSI Device Storage Module.