[ANSS-netops] Getting your PC to autoboot after a power interruption

[Gray Jensen]

For those of you that operate remote Earthworm systems or other
unattended 24/7 PCs, you may have encountered the problem of
the system not rebooting itself when power returns after a power
loss.  This is due to fact that current PCs require that the power
pushbutton on the front of the computer be pushed once power is
available.  Even if you have a UPS and/or a backup generator, 
sometimes they run out or fail to work or somebody accidentally
bumps into your power strip and causes power to go off.  On
more than one occasion we have had to send someone hours
away to simply push the "On" button and then drive back.

The solution is to modify the power supply in the computer to
alway be on when the main power switch in the back is on.
The ATX power supply has an input signal called /PS_ON that
allows the motherboard to turn the supply's power on and off.
It does this by grounding the line.  The power supply can be
made to be always on by permanently shorting the line to 
ground.  /PS_ON is pin 14 on the motherboard power 
connector and is usually the green wire.  Ground is available
on a number of the wires including pin 15 which is black.  
Tying these two together will do the trick.

To see detailed instructions on how to make this modification,
FTP to the address below.

ftp://ehzftp.wr.usgs.gov/gjensen/Autoboot.pdf

Gray Jensen
USGS
Menlo Park, CA
gjensen at usgs.gov