Converting a Computer PSU to a Stand Alone Power Supply

[Rick_Br]

Hopefully this is the right place for this.
I pulled a Thermaltake TR2-430W PSU out of a computer headed to e-cycling with a plan to use it for power an electrolysis tank. The model number is XP550NP. I am having a problem keeping it running for more tan 20 or so seconds. What I ahve done so far:
1. Cut off all the connectors and bundled like colors
2. connected the green power on wire to a black ground
3. connected the brown sense wire to an orange 3.3V wire
4. using 12 volt bulbs I put a load on each primary rail - 1 amp on the 3.3V rail, 3 amps on the 5V rail and 2 amps on the 12V rail.

With this set up the PSU runs and all bulbs light for about 25 seconds then it shuts down. Looking for any and all ideas to get this running correctly.

 

[The Cobbler]

there's hacks on you tube for making them stay on. I remember watching one several years ago .

 

[Wrench97]

The green wire is only a momentary ground to turn on if you leave it grounded it will shut back off.

 

[CoogarXR]

The green wire is only a momentary ground to turn on if you leave it grounded it will shut back off.

Since when? Every old ATX power supply I have repurposed has just had the green wire grounded and nothing more, and they ran forever. It's been 15 years or so since I have used one like that- did something change on newer ones?

 

[lilredex]

This what I have found.....

 

[Wrench97]

Think about how the power button on a PC works, it's a momentary switch, when it's on you hold it in and it turns off.

 

[Jack Ryan]

As an aside, little boards like this one come in useful for making GP supplies.

24 Pins Output Terminal Power Adapter ATX Transfer Board XH-M229 Test Module 821355579610 | eBay

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They can be had very cheaply.

Jack

 

[American Locomotive]

I'm guessing you probably accidentally connected two power rails together you should not have. It should stay on.

The green wire is only a momentary ground to turn on if you leave it grounded it will shut back off.

The green wire is not momentary. The power switch on the computer is momentary, but the computer itself connects the green wire to ground for as long as the computer is on. As soon as the green wire is disconnected from ground, the power supply shuts off. The power switch on the computer does not connect to the green wire.

 

[iron block]

Your pinout diagram has lost the minus signs on a couple of pins. MIght be worth rechecking your wire bundles to make sure that, say +5 and -5 aren't shorted, and the same for +12 and -12. Those would make the supply unhappy and it might well shut down in 30 seconds. See pinouts for more info.

Actually, -5 may not be supported in some power supplies. But -12 definitely is so be sure to verify that one.

 

[Rick_Br]

Regarding green as momentary - I did try just touchong the green to black - PSU started but when I pulled the green away from the black it immediately shut down.

Rick

 

[CoogarXR]

Regarding green as momentary - I did try just touchong the green to black - PSU started but when I pulled the green away from the black it immediately shut down.

Rick

That's what I thought. That's how I have my bench supply setup. I have an old IBM server power supply mounted inside my bench top, and I just have a small toggle switch that connects green to ground. I have two standard filament (non-led) pilot lights on 5v and 12v to serve as a dummy load, and to show that both rails are live.

I used to do the same when using a computer power supply to power security cameras. PC power supplies are great for that. Fan cooled, nice clean 12v, plus they have good short-circuit protection.

 

[cherokee]

Personally, and I know it all comes down to you I would not bother. Yes you can get low wattage power supplies for nothing now, and again IMHO that is because they are worth it....nothing.

Yesterday I just chucked a couple 430's and saved a 550 for someone that wanted to play with it. I only keep if they are over 880W and that is on the fence for a low output build, last PC I built had a 1300W in it, with 800W going to the graphics card alone.

Get yourself an adjustable powersupply, they are not that much and have tons of other uses even if you don't tinker with that stuff.

 

[Rick_Br]

Personally, and I know it all comes down to you I would not bother. Yes you can get low wattage power supplies for nothing now, and again IMHO that is because they are worth it....nothing.

Yesterday I just chucked a couple 430's and saved a 550 for someone that wanted to play with it. I only keep if they are over 880W and that is on the fence for a low output build, last PC I built had a 1300W in it, with 800W going to the graphics card alone.

Get yourself an adjustable powersupply, they are not that much and have tons of other uses even if you don't tinker with that stuff.

I hear ya - I'm actually going in a different direction with electrolysis but this PSU is just pi$%^&ing me off - like I said above I'm in stubborn mode now

Rick

 

[SlappyWhite]

From memory on an ATX PS it was to connect green to any black and leave the connection in place. Then the power switch on the PS should turn it on and off. OR leave the PS switch on (or if it does not have one) and add a switch on the green to black connector. Sounds like you tried something similar, might be worth a second look. If the green to black connection is lost it should turn off.

The PS relies on the motherboard to keep it turned on buy shunting between green and black, the above should hack around that. Why, when the PC is SW turned off it breaks the green to black connection....

 

[flyingblind]

Been a long time but I had to use a resistor on one of the wires to make it think it was powering somthing to stay on. eta I am not even sure where the power supply is now. Been years since I needed a 12 volt power supply. I usually use a battery charger now days.

 

[dogdog]

you don't need that much amperage for electrolysis... unless you are doing some Huge tank size objects. For that 100+ lb old cast iron radiator max I have seen it draw is about 10AMP. and dials down to about 3AMP @ 12V after the initial rusts transferred off. higher voltage makes a difference when there are rust but doesn't seem to want to start. and more rust on the part the easier. I have tried 5V and 12V for etching with salt water. and that worked well, those need some amps.

anyways. nothing I can help on the PSU part. other than not sure if you needed to load up all voltage rails... lots of online instructions just say the 5V or the 12V with a 10Watt resistor (load?) or something to foul the PSU to think there is a load and not to shutdown.

 

[cherokee]

I hear ya - I'm actually going in a different direction with electrolysis but this PSU is just pi$%^&ing me off - like I said above I'm in stubborn mode now

Rick

I get that, you will work if you know what is good for you.....shortly after that comes.......hammer time.

 

[theoldwizard1]

Think about how the power button on a PC works, it's a momentary switch, when it's on you hold it in and it turns off.

The power button sends a signal to the CPU. The CPU shuts down the computer.

Most PSU have a 5V standby line that supplies power as long as there is AC.

 

[wyliesdiesels]

I'm guessing you probably accidentally connected two power rails together you should not have. It should stay on.


The green wire is not momentary. The power switch on the computer is momentary, but the computer itself connects the green wire to ground for as long as the computer is on. As soon as the green wire is disconnected from ground, the power supply shuts off. The power switch on the computer does not connect to the green wire.

yup. the power button actually connects to the motherboard for ATX motherboards & power supplies, which have been around since at least 1996.

Older AT power supplies had a power switch connected directly to the power supply.