Tom on Thu, 16 Jan 2003 14:30:32 -0500


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Re: [PLUG] SCSI cases


Paul,
The load I refered to is a "POWER SUPPLY LOAD RESISTOR, 1A" part number 113 
0282.  Its just a 5 Ohm, 5 Watt power resistor with a disk drive power plug.  
This provides a 1 Amp load for the 5 Volt power line.  The 5 V line on pin 9 
is the 5VSB or 5 V standby power line. 5VSB is used to power the keyboard and 
the keyboard controller  (or ASIC) on the mobo so you can use the power key 
on the keyboard and the wake-on-lan, etc. features.  The 5VSB would be good 
to use for a debounce circuit for an on/off switch.  The ATX power supply 
spec says PS_ON# is supposed to be debounced.  I have used a piece of wire to 
"jumpstart" the ATX clone power supply in a Power Computing Mac Clone 
reliably.  Of course the apparent lightning hit (as evidenced by the charred 
modem port driver chip) probably accounted for the dead keyboard controller 
chip.  
HTH,
Tom

 
On Thursday 16 January 2003 11:08, Paul wrote:
> The 5V line (Pin 9?) is for stand-by power to the mobo.  Could I use
> that five volts to power a debounce IC to control the power-on pin (Pin
> 14)?
>
> I saw the tester for $12.75 (not including shipping).  It's big.  Maybe
> it has a big resitor in it?
>
> Tom wrote:
> >There's one pin that you have to short to ground to turn the supply on. 
> > It's pin 14 (PS_ON#) on the Motherboard connector.  That's the one just
> > to the left of the latch.  You can short it to pin 15 or 16 (COM), the
> > pins inline with the latch or to pin 13.  The Apple power supply works
> > the same basic way but I think the connector is different.  You still
> > need a load on the 5V line.  Cyberguys (www.cyberguys.com) lists one for
> > ~$10.
>
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