FAQ: How do I power my DC-DC PSU on my workbench?

**2k1Toaster** · 06-27-2009, 10:44 PM

Originally Posted by focus_se

I am using a 24 pin atx psu for my workbench. I found some pinouts online but I dont think they were the same, so Ive had to leave it plugged into another mobo.

Anyone out there know the pins needed to "jumpstart" the psu?

A 24pin is exactly the same as a 20pin + a 4pin extension. Most good quality and up actually have the 4pin extension detachable.

So it is still pin 14 shorted to ground.

**blk02si** · 06-28-2009, 12:12 AM

Green Wire shorted to ground

**Wagonmaster** · 08-04-2009, 04:58 PM

I have a Radio Shack power supply that will give me 13.8 volts and 3 amps.

Is 3 amps enough?

**2k1Toaster** · 08-04-2009, 05:04 PM

Originally Posted by Wagonmaster

I have a Radio Shack power supply that will give me 13.8 volts and 3 amps.

Is 3 amps enough?

3A * 13.8V = 41.4W [Watts] at 100% efficiency. Usually those are 85% to 75% efficient, so you really have 31W.

So if you are running less than 31W worth of stuff, you should be ok. Otherwise, no.

**Wagonmaster** · 08-04-2009, 09:11 PM

Originally Posted by 2k1Toaster

3A * 13.8V = 41.4W [Watts] at 100% efficiency. Usually those are 85% to 75% efficient, so you really have 31W.

So if you are running less than 31W worth of stuff, you should be ok. Otherwise, no.

Thanks Toast-Man

**Kitiara** · 08-01-2010, 07:32 AM

Thank you for the tutorial and pics. I was having issues getting mine to run off a jump start unit unit I had (it would start and then stop after a few seconds) I found this and liberated an old PSU from a drawer and a few mins later it was working fine. Now I can get windows etc installed and have it ready to go in the car when I get the monitor.

**vat2010** · 02-24-2011, 08:25 PM

Sparkfun sells a ATX breakout board. From the link http://www.sparkfun.com/products/9558

This is a breakout board for our right-angle, 24-pin ATX connector. Pair this board with the ATX connector and a standard PC power supply and you'll have 3.3V, 5V, and ±12VDC to supply to your project. Make sure you ground the PS_ON pin to enable all of the outputs.

**cdevelasco** · 12-14-2011, 06:55 PM

I seem to have a problem with my set up. I had an Opus 90W PSU powering a car PC and it all worked fine, the car got sold so I took out all of the car PC parts, as a consequence the car PC and the Opus 90W where on the shelf for a couple months.

I built a workbench (according to these instructions) to test the car PC set up before installing it in a new car. I am using a normal 450 W nominal ATX power supply, the 12V output from one of the molex connectors of the ATX power supply is wired to the "Battery" pin of the Opus and also to the "Ignition" pin of the opus 90w (I also added the switch to this wire in order to simulate the car on/off state). The ground/black wire of the same molex connector from the ATX power supply is connected to the "Ground" pin of the Opus 90W. So Basically when I jump start the ATX Power supply (by shorting the green wire to a black wire), the opus LED begins to blink normally as if the power supply was in Idle or stand-by state (Led flashes for 0.1 sec and then is off for a few seconds, then flashes again, etc.). The moment I flip the switch on the Ignition pin in order to simulate that the car is turned on, after about a second I can see that the power LED of the PC Flashes for a second, as if the PC was powering up, however all of a sudden it turns off and the PC never fully boots, the LED on the OPUS also goes to a total OFF state, it never flashes at all and remains off. Its as if the Opus begins to power the PC for a second and then totally turns off, and the LED light of the OPUS 90W stops flashing completely.

Once I disconnect power to the Opus 90W and reconnect it, the LED begins to flash normally again as if it was in idle/stand-by state, however I can't seem to get the opus to power and boot my car PC (which is a Via Epia M10000). Any ideas on what may be going on? I thank you in advance for your help.