Using a USB to power a laptop fan

[Garresh]

Hi everyone. First post here, although I've lurked these forums in the past with questions.

First, the story:

So I've had a Qosmio x505 for a few years now, and it has for the most part served me well. Recently, the CPU cooling fan died. I ordered a replacement part, and swapped it out. Unfortunately, the replacement didn't work. It seems like the motherboard itself is the problem. I've been looking at an alternate solution for a while now. First I considered finding an available output on the power supply, but since it's a laptop it doesn't really have any available. I really don't want to replace the motherboard, and I can't afford to get a new computer for a month or two, so I'm considering making/buying a USB to 3 pin molex adapter.

Something like this: http://www.moddiy.com/products/USB-to-Fan-3%252dPin%7B47%7D4%252dPin-Converter-Cable-%28100cm%29.html

There is some free space in the laptop to place the cables by the fan, so it should be as easy as drilling a small hole in the side of the laptop case. I know this has been asked here before, but my primary concern is that I don't want to start a fire. Although I'm pretty comfortable changing out parts and doing routine computer maintenance, but I'm not really too comfortable with creating my own electrical connections. If the laptop is bricked, whatever, I'll buy a new one in a month or two, but safety issues are a big deal. Anyways, USB puts out .5 amps and 5 volts, and I have both my old fan and the replacement I purchased. Both draw 5 volts. The old one draws .5 amps, and the new one draws .4 amps.

I don't have a link to the new one atm, but here's the specs on the old one: http://www.pchub.com/uph/laptop/88-81229-21553/ADDA-AB7005HX-CD3-Cooling-Fan-.html#

I have no ideas about the wattage. but I figure since the USB and fan both drew power from the motherboard directly, it should equalize without any safety concern, but I just wanted to check. If this checks out I can order that adapter or just make one myself(or ask an electrician family member ) So does this plan check out, or have I overlooked something?

 

[jay_nar2012]

You can make one your self.

Get a USB cable you don't and will never use or get this= http://www.amazon.co.uk/BestDealUK-3-5mm-Barrel-Power-Cable/dp/B003REMLLM/ref=sr_1_2?s=electronics&ie=UTF8&qid=1346758062&sr=1-2#Next

Strip the wires (the USB should have 2 power cables inside colour coded, and i,m talking about the one in the link).

First check if the computer runs without the fan, if it does cut all the wires if not then only cut the black and red and leave the other one and connect that to the laptop (via the fan connector).

Attach the red fan cable to the red usb wire and the black to black and see if it spins.

If it works then get some electrical tape and cover the power wires with it and tidy up the cables.

 

[Garresh]

Oh wow. Nice suggestion on that cable there. And those directions are nice. Just to be clear though, the voltages/amperages match up that there is no fire hazard unless I don't insulate the cables properly?

 

[jay_nar2012]

Wouldn't cause a fire hazard, it would get hot though if you shorted the wires.

 

[Garresh]

Best answer selected by Garresh.

 

[Garresh]

Alright. I think that's everything I need. Thanks for all the help, especially the guide on how to do all this for cheap.