Power Off Sequence - Acuson Corporation Aspen Service Manual

Power-Off Sequence
Theory of Operation
The following power-off sequence is needed to power down the
system in a safe and repeatable manner, allowing the system time to
store important information in battery-backed RAM, and store
Aegis exams to disk without damaging the system internal hard
drive.
After the Aspen system has been powered on, pressing the On / Off
power switch resets the latch on the lOB
boand
and removes the
power-on request. This causes an interrupt to be sent to the System
Controller indicating a power down request has been initiated. The
Aspen system then performs a power-down sequence that will
include completing any disk accesses, closing all files that are open
and any other housekeeping that
is
required.
\ii'lIt'n the housekeeping functions are complete, the System
Controller sends a power off request to the lOB, and the lOB passes
on the request to the Main Power Supply, resulting in all the DC
voltages being turned off, thus shutting down the system.
IMPORTANT:
Never tum off the power by pulling the plug from the wall outlet or
turning off the Main circuit breaker, as it may cause hard drive or MO
failures and you may lose unsaved Aegis system exams.
You should always tum off the system by using the power switch on
the User Interface.
The system will also power off if one or more of the following
occurs:
• AC input power is lost
• The Main Power supply detects a fault (e.g., fan failure or over
temperature condition)
• The main circuit breaker opens
This completes the power-off sequence.
The +5 VDC standby voltage (Vstandby) to the lOB remains on to
monitor the On/Off switch for the next power on request as long as
system is plugged into the wall and the main circuit breaker is on.
1096 Service Manual
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