Tuesday, May 15, 2012

There I Fixed It

(Note: for personal reasons posting may be light to non-existent for a while.)

You have a laptop. A good one, only two years old, and mostly working fine. Now, unfortunately, the laptop fan is — not broken, exactly, but sometimes it doesn't spin up when it should. Maybe the bearings are clogged, the motor may be going bad or perhaps a temperature sensor is malfunctioning.

The reason doesn't really matter — when the fails your laptop runs hot. Really hot. Even a slight extra load, such as watching a Youtube movie, is enough for it to slowly overheat and grind to a halt. It happens increasingly often, and it's becoming difficult to even use the machine by now. You need to do something.

What do you do? You could bring it to a repair center and have them fix it. But the machine is two years old and out of warranty. You're probably within a year from a new laptop anyhow, so a possibly expensive repair doesn't strike you as a great idea. And you depend on the machine every day, so you'd need to find and set up a replacement computer for a couple of weeks while it is in for repairs. Serious money. Major hassle.

You could open it up and hope to find some obvious flaw such as clogged-up dust or a loose cable. But you've already dusted the fan from the outside, these machines are difficult to open without special tools, and integrated laptop motherboards leave very little scope for home repairs. You're far more likely to break something else than to fix anything.

Or, you could take a junk-drawer cooling fan1, a left-over cellphone USB cable, a soldering iron and liberal amounts of gaffers tape:

There, I fixed it
There, I fixed it!

USB ports give you 5 volts and 100mA of power for low-power devices. The fan I found draws 0.4 watts at 5 volts, or 80mA — nicely within the low-power limit. Solder the leads red-to-red and black-to-black, then use tape or heat-shrink tubing to isolate the connections (remember to thread the tubing on the leads before you solder... I always do that).

Gaffers tape works great both to hold the fan and to create a flexible, pliable enclosure to fit onto the air exhaust on the side. Gaffers tape is wonderful stuff — it ­cuts without tools, it's strong and flexible, and the glue doesn't leave any residue. A roll is pretty expensive but it lasts for years at home.

The result? My laptop idles at 75-80° without the fan, and will soon hit critical temperatures with any extra load. With this fix the machine stays between 55-60° in normal use and will remain below 80° even when I run 3-D applications or do intensive image processing. It's not completely silent, but the sound is so soft and muted — the tape dampens any vibrations — that I soon forget it's even there.

It's a hack. But when I can ill afford the time and money to repair or replace the computer, this hack solves my problem at no cost and with minimal effort.

We often underestimate the utility of the hack, the kludge, the temporary patch. It's not as good as a permanent fix, but often it doesn't need to be. If this hack keeps my machine running fine until it's time to replace it, then it's just as good as a real repair. Better, as it took less than an hour instead of many days or even weeks.

"Everything worth doing is not worth doing well", as a wise man put it. "'Perfect' is the enemy of 'good enough'", said another. Words of wisdom.

#1 Aren't you happy you saved that fan a few years ago? All that junk really does come in handy from time to time, no matter what other family members may say.


  1. hehe, nice hack!

    Though, if you want a more elegant solution, see if you can find an independent repair shop, ie. a one man company. Last year I had a problem with the fan in my now 5 year old macbook, and found a guy in town who fixed it for 60 euros including a new fan (that he actually got from ebay cheap...).

    Good luck!

  2. Of course. But then I'd have to take the time to find a shop, bring the machine, be without it until they fix it...

    This was something I could do from start to finish while waiting for dinner to get ready.

  3. Yeah, it's a neat hack. What I did was that I left my macbook to the repairman an afternoon when I had no use for it, and he investigated it. The morning after I picked it up and we booked a time for the actual repair to take place (a cpl of days when I was out of town anyway not needing it).

    But I understand completely, if the hack works, there's no need for another fix..


  4. That's pretty fast, actually.

    I think this is a bit more complicated though. The fan hasn't stopped working altogether; instead it idles at low speed when it should spin up to high. And sometimes it _does_ spin up. It's not a software issue (it's not under OS control at all), so I suspect perhaps a faulty temp sensor somewhere or something.

    Also, I just like the simplicity of the extra fan ;)

  5. nice work.. I've done some basic work on laptops, thought a fan shouldn't be that hard but find for example


    looks like a real mess. I'd have gone for the gaffer tape solution too..

    my desktop died this weekend after only 2 years. I'm going to build a desktop machine now, tired of getting proprietary OEM builds that can't be fixed..

  6. And as I said in the comment above, it's not at all clear the actual fan is to blame. I might spend a lot of effort replacing the fan only to find out it's something unfixable on the motherboard.

    What I _would_ like to do is make this a real USB device. That way I could control the power programmatically, and have it turn on or off in response to the temperature just like a "real" fan. Then replace this found fan with a low-profile one. If I had the time for a small hardware project that'd be a good one.

  7. Love the idea of an USB fan!!!!


  8. ddon: actually, I'm really considering it now. It shouldn't be too difficult; there's integrated USB controllers available for almost nothing, and I'd basically just want to use it as an on-off switch.

    I have an older small laptop with a similar issue. With a controllable external fan I could revive it and set it up as a low-power home server. It'd be useful beyond just keeping this one alive for a while.

  9. Just saw this now. Very sweet! Clever little idea, and really geek-charming, in spite of the hideous look :)

  10. Let me assure you that it looks plenty worse in real life :)


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