Can't Jumpstart PSU

[mmntech]

I'm having a couple power supply problems. I have two old ones that I use for powering 12v battery chargers for RC equipment. My first one, an old Aopen 250w all of a sudden decided it would only output 10.1v. So I swapped it out with this other 350w noname one I had. It's a 20-pin ATX supply with a four pin 12v motherboard connector. Problem is I can't get it to jump start. Normally, you bridge pins 13 and 14 (thin green wire with black ground) of the mobo connector and it should power up provided there's a load on it. I connected a couple of fans to it to provide a constant load. However, when I bridge the correct pins, it fires up for a split second then shuts off again. Now I know this PSU works fine in a computer. Any ideas what I'm doing wrong

 

[jonnyGURU]

Originally posted by: mmntech
I'm having a couple power supply problems. I have two old ones that I use for powering 12v battery chargers for RC equipment. My first one, an old Aopen 250w all of a sudden decided it would only output 10.1v. So I swapped it out with this other 350w noname one I had. It's a 20-pin ATX supply with a four pin 12v motherboard connector. Problem is I can't get it to jump start. Normally, you bridge pins 13 and 14 (thin green wire with black ground) of the mobo connector and it should power up provided there's a load on it. I connected a couple of fans to it to provide a constant load. However, when I bridge the correct pins, it fires up for a split second then shuts off again. Now I know this PSU works fine in a computer. Any ideas what I'm doing wrong

You don't have any load on any rail other than the +12V. Might have been how you killed the old Aopen PSU too.

 

[brblx]

putting, say, a 10ohm resistor on the 5v rail should fix that, no?

 

[mmntech]

Originally posted by: brblx
putting, say, a 10ohm resistor on the 5v rail should fix that, no?

Yeah, I suppose I could do that. I found a guide. Then again I might as well just get a proper bench unit instead.

 

[SparkyJJO]

Something else that usually works for me is just connect some old HD to the power supply. Creates enough load on the rails to make it operate normally.