I’m asked to look at a laptop that has suddenly stopped working.

I push the power button, all the LEDs light up simultaneously, for about 30 seconds, and then everything powers down.

I can hear the hard drive spin up, so I try removing the battery, pressing the reset button (under the laptop), but no joy.

The display is totally dead… nothing to see… no beeps.

I then notice that the CPU fan doesn’t spin up… I think ‘thats it!’ probably a faulty fan/heatsink.

I dismantle the laptop. While mostly dismantled, I try to power up again, and sure enough, the fan doesn’t spin, and the top of the cpu gets warmer and warmer until it powers down again.

Yep, a bad fan… the cpu starts running, the bios (or the electronics) notices the fan isn’t spinning, so it waits, the CPU gets too hot, so the bios/electronics powers down the system. Simple huh?

So I order a replacement heatsink/fan part from HP.

I need to go out for a few hours, but while I’m out, I decide to check the fan on another system (when I get back), and see if I can force the fan to spin with a slightly higher voltage (or maybe fix it by cleaning out the dust).

The fan is not as dirty as I would expect, so I just plug it into 5 Volts, and it starts spinning right away! I get a bad feeling about this… If the fan works, then I’ve wasted money buying a part I don’t need, and the actual problem is elsewhere!

I start testing voltages on the motherboard, and it looks like most of the board is powered up correctly, but the fan plug has no power (and I’m not an electronic engineer), so I cannot track down which component is causing the problem… damn!

Looks like a replacement motherboard is needed… After checking the prices, it looks like it will cost the customer about $750!!!

Needless to say, he decides its cheaper to get a new laptop, and drop the current HDD into a usb enclosure, so that he can recover his data.

So its: no fix, no charge, and I really need to be more thorough in checking hardware.

Anybody want to buy a cheap heatsink/fan unit?