Operate computer power supply independently??

J

Jake W. K.

Guest
I have a power supply from a previous computer I've since scavenged
for parts. It is a Hipro power supply with a standard power supply
connector for the motherboard. Is it possible to crosswire or rig
this power supply to where it will operate independently, powering an
additional hard drive or two which are linked by IDE cable to a mother
board in an adjacent case? If it is possible, how or where can I
find out which wires to crosswire to accomplish this?

I've run out of space and power connections in the existing box, which
already contains and powers four hard drives plus two disc drives.

Any help would be greatly appreciated?


Jake
 
Put a 5 ohm power resistor across the +5V output and ground. This will
generally be a sufficient load to make the supply operate independent of the PC.
An amp of current is enough in almost all cases to make the switching regulator
continue to operate.
Make certain your power resistor is rated at more than 5 watts. I would
pick a ten watt one myself to make sure I had plenty of "head room".

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
 
Sir Charles W. Shults III wrote:
Put a 5 ohm power resistor across the +5V output and ground. This will
generally be a sufficient load to make the supply operate independent of the PC.
An amp of current is enough in almost all cases to make the switching regulator
continue to operate.
Make certain your power resistor is rated at more than 5 watts. I would
pick a ten watt one myself to make sure I had plenty of "head room".

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
Click to expand...
I would also connect the black wires of one supply to the black wires of
the other supply. Both are signal-ground, just to
have a reference other then the IDE cable, between the supplys.
rw
 
Well, that goes without saying- no common ground, no way to compare logic
signals. But I suppose I assumed that he would know.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
 
Doing that strikes me as a particularly risky and non-ideal thing to do. AT
and ATX power supplies, in the interest of being cheap, do not regulate the
power rails with exceptional tolerance. If one of them is a fair amount
higher than the other (about 0.7 Volts), I can envision the I/O lines on one
of the devices going high, and feeding power up through the internal CMOS
diodes to the other device's power rails. In such a case, exceptionally
high current may flow and lead to catastrophic destruction of either your
hard drive(s) or your motherboard.

That being said, I've connected such a configuration up once (when I needed
data off of a hard disk in another computer, who's power connector didn't
want to come off). I operated it for a few tens of minutes without
destroying anything. If you were to attempt such a venture for a permanent
solution, I would recommend connecting several of the black wires together,
and the green wires (on the motherboard connector) of the power supplies
should also be connected. This green wire needs to be pulled low by the
motherboard to turn on the power supplies. As a safety feature, I would
connect a comparator, transistor, and other necessary circuitry up such that
the power supplies would automatically power down if the two 5V power
supplies rails deviated by more than a certain threshold of say 0.5 Volts.
You may need some circuitry to give it a delay before deciding to shut down
to provide for temporary transient conditions (such as during power up).

Howard Henry Schlunder


"Jake W. K." wrote in message news:KLUSPx2nrnlnSm58dvMpQyvErbNV@4ax.com...
I have a power supply from a previous computer I've since scavenged
for parts. It is a Hipro power supply with a standard power supply
connector for the motherboard. Is it possible to crosswire or rig
this power supply to where it will operate independently, powering an
additional hard drive or two which are linked by IDE cable to a mother
board in an adjacent case? If it is possible, how or where can I
find out which wires to crosswire to accomplish this?

I've run out of space and power connections in the existing box, which
already contains and powers four hard drives plus two disc drives.

Any help would be greatly appreciated?


Jake
Click to expand...



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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On Mon, 14 Jul 2003 14:28:28 GMT, "Sir Charles W. Shults III"
<aichipREM@OVEcfl.THISrr.com> wrote:

Well, that goes without saying- no common ground, no way to compare logic
signals. But I suppose I assumed that he would know.
Click to expand...
Please don't assume or presume that. Thanks for the information you
did give...but did you see where I asked how or where can I
find out which wires to crosswire to accomplish this?

How do I determine which of the leads you are talking about?


thanks,
Jake
 
The black leads are your common ground. The red leads are the +5V outputs.
The yellow leads are +12V. You can connect the power resistor from the red to
the black and that should be sufficient to make the supply run. Then you can
check any other voltages with a standard voltmeter.
I installed a system with the standard power plugs for PC devices on my work
bench and can troubleshoot them without having to plug them into a PC. Hard
drives, CD-ROMs, etc. are pretty easy to play with this way.
When you use this with a computer, you will only want to connect your common
ground. If you hook the power leads from this supply to the power leads in your
PC, the supplies will buck each other and something will smoke. Just connect
the ground leads, no more.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
 
On Mon, 14 Jul 2003 16:41:16 +0100, Howard Henry Schlunder wrote:

CMOS diodes
Click to expand...
Huh?

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx
 
Probably referring to the devices inside the ICs.

Cheers!

Chip Shults
My robotics, space and CGI web page - http://home.cfl.rr.com/aichip
 
"Jake W. K." <jake@gimmejam.com> wrote in message
news:yvISP5NfXSGdXNFQx2VbJIZ=0zCV@4ax.com...
On Mon, 14 Jul 2003 14:28:28 GMT, "Sir Charles W. Shults III"
aichipREM@OVEcfl.THISrr.com> wrote:

Well, that goes without saying- no common ground, no way to compare
logic
signals. But I suppose I assumed that he would know.


Please don't assume or presume that. Thanks for the information you
did give...but did you see where I asked how or where can I
find out which wires to crosswire to accomplish this?

How do I determine which of the leads you are talking about?
Click to expand...
This may help:
< http://xtronics.com/reference/atx_pinout.htm >.

Connecting pin 14 to ground is required to get the power-supply to turn on.
Wired to a switch on the case, perhaps?
 
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