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Hotwiring a PSU

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Jan 15, 2001
I have this 300W ATX 2.03 Uneec PSU that I borrowed from a friend of mine...What I'm trying to do is get it to run without a mobo attached...I've done it with the previous versions of ATX power supplies but 2.03 it doesn't seem to work...

Here's what I'm doing, I connect pin 14 (pwr_on) to common and pin 8 (pwr_ok) to common...then I flip the switch and it powers up for a second then shuts down

Has anyone expirenced this problem and anyone solved it?
If I remember right this is how I did it.jump the green wire to a ground wire and that will do the trick.

EDIT: I just tryed it green to any black works,I didnt get the problem your getting...Are you using the green wire?
have a look here..........

yup, i've been doing it with the black wire and the green wire...still the same problem...i get juice for a second and then it shuts off...
What are you using to connect the green and black leads? You probably want to use some wire of the same gague or bigger as the power supply wire. And try and use copper wire (or gold, if you can get it).
nope the PSU isn't broken & I'm using 16 gauge...thats bigger than both the pwr_on and the com's
I have had that problem with a bad PSU and a bad MBD.
It sounds like a bad PSU though.
Well I just got a Second Power Supply for use in this case and I wanted to hotwire it and the green to black does not work. Its a Power Tronic 320w PSU Model PM-S320U and to get this PSU to kick on you had to go *GREEN PS-ON* to *GREY P-OK* for it to kick.up and stay on. I tried what he said green to black and it kicked on for a half second then died. So this might help out some.

Well, I tried PWR_ON to PWR_OK and doesn't work either, it still powers on for a second and then powers off....
I'm having the EXACT same problem. I get it to power up for a second, then it shuts down. And I know the power supply is good, it's been tested rigorously beforehand. I've got the green wire connected to the black wire right next to it. I'm going to try with a few other black wires, like how they have the diagram here.

More specifically, I'm going to connect the green wire to the black wire they have indicated in the attached picture from the above link.

Guess I oughtta think more, before I start cutting and splicing wires, but damn if it ain't the allure of the butt connectors.
Well, after some unsuccessful attempts, I found this out:
1. I'm screwed.
2. It doesn't matter which black wire you connect it to, you get the same results. Fan spins for a few seconds, then dies.

I have no clue why, and I have no resolution. Fortunately, I was just trying to setup a mobo testing rig, so I was able to salvage a power button from an old PC case. Which, in hindsight, would have been quicker and easier. But it would have meant that I wouldn't have gone to Radio Shack and spent over $95 on various toys, including a nibbler.

But if anyone finds out why this happens, I'd really like to know. The power supply I was using (if it helps) is an Astec 90W power supply I stole out of an old Dell OEM case.
For anyone who has gotten this to work, what kind of power supply did you use? I don't wanna get a power suppy to hotwire it for a test rig and not have it work!.
Try this [just an idea]:

Green to Black
Red to Grey

this should work and if it doesn't try putting a load on the 12v line [like a fan or something.] I tested my ATX connector with my computer powered up and found the red wire to be connected directly to grey...
[Oc]Wa11y (Jul 16, 2001 02:28 p.m.):
So green to black, red to grey....
Where's the 12V line? Is that just a normal 4-pin molex? I thought those were 5V.

4-pin molex has 1 12v [yellow], 2 gnd [black], and 1 5v [red.] 5v is used for drive logic and 12v for the motor.

additionally if that doesn't work and both PS are of the same type then connecting *all* wires in parallel should also work. I'm not sure if it is required but you may want to make sure that the one PS is not grounded to its chassis. That is to say if you test from black to one of the PS screws it conducts well then you should locate the connection and insulate it. This is required for 2+ AT supplies but I'm not sure if it applies to ATX.
I know that this is an old thread, but I wanted to post this information to help solve this problem for anyone else who may need it.

First of all, for the PSU to work, there must be a load placed on it. You can rig up something like a 3.8 ohm 20W resistor soldered to two pins. I just used an old hard drive that still spun up. Connect this to any of the four pin connectors. Also, a case fan doesn't seem to have enough draw on it.

PSON# needs to be connected to a common ground (black) , at all times, for the PSU to work. A momentary connection may need to be made between PWRGOOD and +5 VSB. I think this second connection charges a capacitor. When I first tried PSON# to common, nothing happened until I shorted out PWRGOOD and +5 VSB. Now, I just need to connect PSON# to common.

Hope this helps
I know very little about how the Wireing works on the Computer.

but i do know that Red=5Volts and Yellow=12Volts.

Does any of you know of any info sites that can tell me more on this subject.

Thank you all for your help.