Damaged PC power supply?

[jackda]

I bought a ATX PC power supply. I shorted the Green wire and and put a load on the 5V line and got 12V. I then opened the case and cut some wire out and now I can't get the power supply to work. Did I damaged the power supply. Any ideas? When I ground the green wire the fan kicks in for a second.

[jkmadsci]

What wires did you cut?

[jackda]

I cut all the connector off then tie a 10 ohm resistor to the 5V line and shorted the green to ground. I see one fuse on the board. Are there any more?

[jkmadsci]

Is it possible that when you cut the wires you have 2 different wires touching eachother?. if fan spins then fuse cant be blown. Usually no other fuses on supply

[jackda]

Yes it's possible. Is there a fix of any kind?

[Andrew0820]

Generally, there is a single fuse -- sometimes in a fuse clip, but most usually simply soldered to the board. The fan bump is characteristic of A/C power without a DC load.

1. Make sure when you cut the wiring that you did not get any shorts. I will sometimes bundle cut ends from the same rail, slip a piece of heat shrink over them and shrink fit. This holds the wire together and isolates the ends.

2. Leave the Power_On wire (green) unattached for the time being.

3. Make sure your load resistor is intact -- test with a multimeter. Also make sure this resistor has good contact with the 5v rail (red) and DC ground (black) The DC ground is isolated from the case ground, so grounding the resistor to the case structure will not work. Be sure the 5v rail does not have a DC ground except thru the resistor. If any of the DC rails are directly grounded, the overload circuitry will kick in and the latch the PS into overload until it is reset.

4. When all of the above have been checked, power up the AC and then touch the exposed end of the green PS_On to an exposed DC ground (black). There is little voltage here, but stay away from anything else inside the case. There are a number of places that you can get seriously whacked. If the PS kicks on, breaking contact between PS_On and ground will shut it down. Be careful not to allow any exposed ends to touch any other exposed components in the case. Unplug the AC and give the caps time to leak down before doing anything else inside -- they can hold a charge and will make you unhappy if you get into the wrong spot.

Let us know what happened.

[jackda]

I did as you said and still the same thing. Theres 8 ohms between 5V and DC ground from a resistor on the PCB. When I touch the green wire to DC ground I get a jump on the 12V line and then it dissipates. Thats why my 12V fans turn on for a moment. Is there a certain way to reset the Power Supply? It sure is funny that it was working before I openned the case.

[jackda]

I touched the green wire to -12V and the power supply turned on. There a tone that I can hear. Is there a speaker on the Power supply? I followed the green wire on the PCB and found a dead 10kohm resistor. I'll have to change it out. Can I damage the power supply by putting -12V on the line? Do I have to put a switch on the Green wire to start the power supply normally? Thanks guys.