cant figure out what went wrong, my car adaptor isnt working now

[sdat1333]

late last week i got my PSOne car adaptor for use on my LCD screen. So i cut off the cig lighter end and figured out which one was ground and wich was power and hooked it up to a molex on a PSU i use for a low end duron system. It worked fine, so i let it be. Anyways now that Im nearing teh end of my mod, I went in to hook up the switch for the adaptor, so I leave the ground to flow thru freely, and put the switch on the 12v line going into the transformer, turn on the system, measure with a MM while the swithc is off, no current so its perfect. Turn the switch on and the PSU cuts out. Im assuming theres a short somewhere but I cant seem to find it. I tried testing it the way i did when i got the adaptor and it still gave me problems so i went away for ~ 1hour and came back, tested it the way i did when i got it, and it worked. So i hook up the switch again, and it doesnt work. So now its a day later and i cant get it to work at all

pls help me

Sean

 

[chopsuwe]

Some older power supplies like to have some load on them or they will switch off again. Connect a car tail light bulb or two to 5V.

 

[SacLANd]

you were trying to measure amps on an unloaded circuit? not a good idea. at that point, its whatever gives out first, your fuse on the MM or the parts on what you're measuring.

 

[theshadow27]

did you hook the switch up across the leads so that when you turn it on it shorts out the PSU? cause thats what it sounds like. hook the switch up to break the circut, not short it