Running power supply without motherboard


J

John

I have a tower case, that I want to use to house three DLT drives and
have an internal to external SCSI cable on the back to connect it to
my main PC. Is there a way to get the power supply in this case to
power up without a motherboard attached to it? I assume if I have any
old AT cases around this might work right off no? Let me know for
both ATX and AT as I'm not sure which one I will find in my available
cases. Thanks.

JR
 
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W

William W. Plummer

You might want to get the ATX power supply spec from www.intel.com . To
get an ATX PS to turn on you need to ground the light green wire 4th from
one end of the 20-pin connector. You can use the black wire next to it in
the 3rd pin as the ground. Just jam a paper clip between the two.
 
G

Gary Tait

I have a tower case, that I want to use to house three DLT drives and
have an internal to external SCSI cable on the back to connect it to
my main PC. Is there a way to get the power supply in this case to
power up without a motherboard attached to it? I assume if I have any
old AT cases around this might work right off no?
AT, yes, it will work straight to power your HDDS.
Let me know for
both ATX and AT as I'm not sure which one I will find in my available
AT will require the power PS_ON line to be connected to ground.
 
N

Nil Einne

AT will require the power PS_ON line to be connected to ground.
Don't you just have to push the power button? I was under the
impression (from experience) that most, if not all AT power supplys
have a direct power switch. I.E. the button/switch directly turns on
the power by completing the circuit between live and neutral ala wall
socket power switches etc. There is no need to connect anything on the
power connectors.
 
W

William W. Plummer

Nil Einne said:
Don't you just have to push the power button? I was under the
impression (from experience) that most, if not all AT power supplys
have a direct power switch. I.E. the button/switch directly turns on
the power by completing the circuit between live and neutral ala wall
socket power switches etc. There is no need to connect anything on the
power connectors.
You might be commenting on my msg regarding getting an ATX power supply to
come on. I was assuming the poster was trying a MB, PS, etc on a table top
with no case. So, no power switch or reset. The older AT power supply
design does not support the smart ("hold in for 5 seconds to turn off")
power switch logic. So, my comments don't apply.

Again, get the ATX power supply specs from www.intel.com if you want the
true poop. But here it is in a nutshell. That ATX supply has an always-on
5 volt supply that allows the smart power button to run even when the
"computer" is off. The black rocker switch on the back of the PS allows the
entires thing to be turned off. When you jab the power button, it sets a
flop that grounds the light green wire into the PS. This tells the power
supply to turn on in order to bring up the computer. If you have the power
supply alone and want to measure its outputs, just short the light green
wire to the black (ground) wire next to it. These are the 3rd and 4th pins
on one side of the 20-pin ATX MB connector. If you have a MB and PS
connected, but no case, just use a screwdriver tip to short the pins where
the power switch connects. That will simulate jabbing the power button on
the case.
 
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N

Nil Einne

You might be commenting on my msg regarding getting an ATX power supply to
come on. I was assuming the poster was trying a MB, PS, etc on a table top
with no case. So, no power switch or reset. The older AT power supply
design does not support the smart ("hold in for 5 seconds to turn off")
power switch logic. So, my comments don't apply.
No. I was referring to Gary Tater's comments who was talking about AT
power supplys. I am aware of the differences between ATX power
supplies and AT power supplies.
 

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