Thread: Computer Power Supply Help

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I aquired 2 computer power supplies. I am wiring up a MIB and some other props with wiper motors. I figured out the wiper motor wiring and they worked fine with a 12V battery hooked up. I jumped the green wire on the power supply harness to power it up and it turns on.My power supply looks just like scary terry's. The wiper motors turn on , but goes to slow, when I hook them up to the 5V side of the harness but when I hook it up to the 12V side, it shuts it down.
Any help would be much appreciated.
Thank you

Never mind. I found my answer. A $1.99 10 ohm 10 watt pre-load resistor is all I needed.

Im Still stumped. I put in the resistor as stated in the tutorial. it worked great at first then i turned it on and off a couple times and now its doing the same thing it did before the resistor was installed.
PLEASE HELP!!!!!!!

How many amps are the power supply and wiper motors rated at?

The motor is rated at 9.4 amps and the PS is rated at 12 amps.

Someone check my math, but I think you need a resistor thats rated to handle 112.8 watts if you are drawing 9.4amps and 12volts. Man, high-school electronics suddenly seems so long ago. Your 10watt resistor is probably fried.

OK, So do you have any idea what I could do? I just looked at the motor and it doesnt say what the amps are. I thought It was 9.4 but that was a different one. Its just a small wiper motor from a ford escort. Did I waste my money on these power supplies?
Thanks

Ok, I did some checking on Ford Escorts and they generally have 20amp fuses on the wiper motors which means they probably draw 14-16amps. If thats correct you now need a 10 ohm resistor rated at 200watts. Anybody care to check my math....please.

Thank you for doing the research. I dont think that such a thing exists. I googled it with no joy. So, if thats the case, how does everyone run wiper motors with a Power supply from a computer?

I think my brain is finally into the correct gear. Your power supply is only able to safely provide 12amps at probably 12-19volts. Your motor needs lets say 16amps. The reason it works slowly on the 5volt side of the harness is because when the voltage is lowered the amps are increased. Even if you aquire a 200watt (pricey) 10ohm resistor you will be drawing more amps than your power supply is designed to handle and the resistor and the power supply will both get HOT! I would suggest a motor that uses significantly fewer amps.