Repurposed Power Supply

svec70 · 11-24-2008, 03:25 PM

I plan to rewire a couple of Dell HP-P2507F3P 250 watt power supplies that I have pulled from some old Optiplex machines. Does any one have the pin out specs for the 20 pin plug coming from the power supply? I want to wire a switch in line with the power connections to turn the power supply on and off but even with a load such as a 10 ohm 10 watt resistor across the 5 volt leads, the power supply is not coming on. Does anyone have the wiring specs for this power supply?
Many thanks,
Bob G.

**wrench97** · 11-24-2008, 03:39 PM

If the supply doesn't get the pwr_Ok signal on the grey wire it won't come on you have to jump pin 8 and pin 4(5v)> Test your power supply with a multi meter

svec70 · 11-24-2008, 04:47 PM

Thanks for the lead. I jumpered 4 and 8 but got nothing. I do have 5 v on the purple lead but until the psu is on I don't think I will see 5 v on any of the red leads.

The PSU is out of the case in a stand alone mode. Is there any other way to fake it into thinking it is in the PC and connected to the mother board so that it will power up.

Thanks again

Bob

**linderman** · 11-24-2008, 05:13 PM

did you try jumper the green wire to any black wire in the main plug then turn the switch on @ back of power supply

**linderman** · 11-24-2008, 05:14 PM

AT YOUR OWN RISK & DONT RISK WHAT YOU ARE NOT WILLING TO LOSE !!!!

try to jump the 5V wire to the grey wire (power good)

**wrench97** · 11-24-2008, 05:19 PM

I am assuming your not trying to use this as a pc power supply but as a power source for something else?
Try using a case fan that has a 4pin Molex connector for load on the supply.

**linderman** · 11-24-2008, 05:29 PM

http://pinouts.ru/Power/atxpower_pinout.shtml

see if your wiring pattern matches these ....... you need to look at the snap lock for orientation

svec70 · 11-24-2008, 06:29 PM

Thanks everyone for the ideas. The final solution that appears to be working is to connect the green to the gray on the P1 plug. I have loaded the circuit with the 10 ohm resistor and also have a 12 volt car lamp and an old hard drive connected.

My use for the power supplies has to do with model railroading. I have built a number of circuit boards to interface physical devices on my layout with the parallel port on an old machine. The boards for the most part use 5 volt logic...hence the repurposed supplies.

Thanks again.

**magnethead** · 11-25-2008, 05:22 PM

I use an old 350W to power my hobbies in the dorm that i dont have power bricks for. If i'd had seen this post sooner i'da posted how i did it.

11-24-2008, 03:25 PM	#1 (permalink)
svec70 Registered User Join Date: Nov 2008 Posts: 3 OS: Windows XP	Repurposed Power Supply I plan to rewire a couple of Dell HP-P2507F3P 250 watt power supplies that I have pulled from some old Optiplex machines. Does any one have the pin out specs for the 20 pin plug coming from the power supply? I want to wire a switch in line with the power connections to turn the power supply on and off but even with a load such as a 10 ohm 10 watt resistor across the 5 volt leads, the power supply is not coming on. Does anyone have the wiring specs for this power supply? Many thanks, Bob G.

11-24-2008, 03:39 PM	#2 (permalink)
wrench97 Moderator, Hardware Team Join Date: May 2008 Location: S.E. Pennsylvania Posts: 18,560 OS: Win7	Re: Repurposed Power Supply If the supply doesn't get the pwr_Ok signal on the grey wire it won't come on you have to jump pin 8 and pin 4(5v)> Test your power supply with a multi meter __________________ Power Supply and Selection

11-24-2008, 04:47 PM	#3 (permalink)
svec70 Registered User Join Date: Nov 2008 Posts: 3 OS: Windows XP	Re: Repurposed Power Supply Thanks for the lead. I jumpered 4 and 8 but got nothing. I do have 5 v on the purple lead but until the psu is on I don't think I will see 5 v on any of the red leads. The PSU is out of the case in a stand alone mode. Is there any other way to fake it into thinking it is in the PC and connected to the mother board so that it will power up. Thanks again Bob

11-24-2008, 05:13 PM	#4 (permalink)
linderman Moderator, Hardware Team Join Date: May 2005 Posts: 20,437 OS: win 2000 pro / Win XP pro My System	Re: Repurposed Power Supply did you try jumper the green wire to any black wire in the main plug then turn the switch on @ back of power supply __________________ I still know nothing and I respect that fact, striving to improve and, along the way, help anyone that comes from the place that I used to be! Power Supply Selection LEARN TO BACK-UP YOUR DATA FREE & EASY YouTube - Runtime Software DriveImage XML tutorial

11-24-2008, 05:14 PM	#5 (permalink)
linderman Moderator, Hardware Team Join Date: May 2005 Posts: 20,437 OS: win 2000 pro / Win XP pro My System	Re: Repurposed Power Supply AT YOUR OWN RISK & DONT RISK WHAT YOU ARE NOT WILLING TO LOSE !!!! try to jump the 5V wire to the grey wire (power good) __________________ I still know nothing and I respect that fact, striving to improve and, along the way, help anyone that comes from the place that I used to be! Power Supply Selection LEARN TO BACK-UP YOUR DATA FREE & EASY YouTube - Runtime Software DriveImage XML tutorial

11-24-2008, 05:19 PM	#6 (permalink)
wrench97 Moderator, Hardware Team Join Date: May 2008 Location: S.E. Pennsylvania Posts: 18,560 OS: Win7	Re: Repurposed Power Supply I am assuming your not trying to use this as a pc power supply but as a power source for something else? Try using a case fan that has a 4pin Molex connector for load on the supply. __________________ Power Supply and Selection

11-24-2008, 05:29 PM	#7 (permalink)
linderman Moderator, Hardware Team Join Date: May 2005 Posts: 20,437 OS: win 2000 pro / Win XP pro My System	Re: Repurposed Power Supply http://pinouts.ru/Power/atxpower_pinout.shtml see if your wiring pattern matches these ....... you need to look at the snap lock for orientation __________________ I still know nothing and I respect that fact, striving to improve and, along the way, help anyone that comes from the place that I used to be! Power Supply Selection LEARN TO BACK-UP YOUR DATA FREE & EASY YouTube - Runtime Software DriveImage XML tutorial

11-24-2008, 06:29 PM	#8 (permalink)
svec70 Registered User Join Date: Nov 2008 Posts: 3 OS: Windows XP	Re: Repurposed Power Supply Thanks everyone for the ideas. The final solution that appears to be working is to connect the green to the gray on the P1 plug. I have loaded the circuit with the 10 ohm resistor and also have a 12 volt car lamp and an old hard drive connected. My use for the power supplies has to do with model railroading. I have built a number of circuit boards to interface physical devices on my layout with the parallel port on an old machine. The boards for the most part use 5 volt logic...hence the repurposed supplies. Thanks again.

11-25-2008, 05:22 PM	#9 (permalink)
magnethead Registered User Join Date: Mar 2006 Location: Texas, USA Posts: 3,570 OS: Vista ultimate 32bit My System Blog Entries: 3	Re: Repurposed Power Supply I use an old 350W to power my hobbies in the dorm that i dont have power bricks for. If i'd had seen this post sooner i'da posted how i did it. __________________ For proper support: what are you running? graphics, cpu, m/board, ram, PSU brand wattage PCI-E requires 26 amps at 12 volts. That's a 650W PSU. Power Supply Info and Selection . Info on thermal compounds & application . TEST PSU USING MULTI-METER . Bench Testing Your System