I am trying to get some PC power supplies to work with no computer attached. I know they won't start without a load so I have tried connecting up a floppy drive, hard drive, and CD drive at the same time but the power supply still won't come on. It is one of the newer types of supples with no on/off switch and a 20 pin connector that attaches to the mother board. To be specific it is a Power Tronic PK-6145DT3
145W power supply from a gateway computer. Any help would be greatly appreciated. Thanks
Hold the connector pin side up, with the tab facing you. Pins are numbered from right to left, back to front. Thus, the pin on the right, in the row farthest from you is pin 1, and the pin on the right in the row nearest you is pin 11. PS_ON# is pin 14. Connect that to a ground (pin 15, or one of the others given below) using a jumper wire. That will tell the supply that you want it to be on. You can use this as an ON-OFF switch, by simply connecting it with a toggle switch.
If you short it to ground, and it still doesn't start up, the supply may have a minimum current requirement. In that case, you can get some big sandstone resistors and supply a load for it. From what I've heard, a 1A load on the 3.3 and 5V supply will be sufficient. A 3.3 ohm 5W resistor from one of the 3.3V pins and a ground, and a 5 ohm 10W resistor from one of the 5V pins and ground will usually get it going. The resistors may get a bit hot, so mount them someplace where the fan blows on them, and where you can't bump your hand into them.
The 3.3V pins are 1, 2, and 11, and the 5V pins are 4, 5, 19, 20. The ground pins are 3, 5, 7, 13, 15, 16, and 17. You will know if there is power by monitoring pin 8, which is the PWR_OK pin. It is like a TTL output, 5V means YES, 0V means NO, and you can't draw more than about 4mA from it (to drive an LED, for example.)
Search on the web for the 'ATX/ATX12V Power Supply Design Guide' for more information.
and search for Antec. The "Antec Power Supply Tester #77003" is $9.99. It plugs into the 20 pin ATX power supply connector and has a on/off rocker switch. Is it worth your time to jury rig something that may r may not work when you can add a simple tool to your tool box that will let you check a power supply in a couple seconds?
ATX supplies need a the lead labeled PS_ON to ground (or is is +5V SB) for them to turn on. Some ATX supplies I've played with run happily without a load, others immediately go to shutdown due to overvoltage protection kicking in. If you see the fan just begin to move and then stop then you can be sure the PSU needs a load on +12V and/or +5V.
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