Maté el ordenador…

Well, I didn’t. That was only to introduce the murder’s weapon : Yerba Mate. This is some highly conductive beverage that, oddly enough, make serious damage when split over the keyboard of an Asus X53S laptop.

The murder's weapon.

Emergency procedure: turns everything off, unplug the battery and power outlet, and let any liquid flows out and dry for a few days. Asian technic: put the device in a closed bag with rice, which will absorb humidity.

If on the contrary you are the kind of guy to carry on with your thesis manuscript whatsoever, even if your keyboard misbehaves and despite pyrotechnic effects coming from the inside of your computer, here is a way to bring your laptop back to life.

DISCLAIMER : Fiddling stuff randomly is the best way to learn, but also to hurt yourself. I can’t be held responsible for any injury, death, or destruction that might occur following this article. Be careful, unplug power supplies, and never let a hacked device without supervision unless you are sure of your hack.

Legal aspects being detailed, let’s hack!

In a nutshell: the motherboard has been seriously damped in maté. Careful cleaning done, two transistors have burst (MTB20N03AQ8) and another one (IT8572E) with pins oxidized by the beverage.

First ones are not available in France, but there are equivalents largely supplied. (Farnell, Mouser, RS…).

The second one is much more difficult to find. So let’s assume some hot-air rework will be enough.

I’ve considered buying a new motherboard from Aliexpress or eBay, but it turns out kind of expensive, whereas repairing my current motherboard seemed a reasonable challenge, if the diagnostic was correct. And if not, I can afford buying two transistors for nothing, and pick a new mother board later.

During repair, I noticed that a resistance close to one of the transistors I was changing looked very bad. Ohmeter spoked: infinite resistance, whereas the other transistor presented a similar design with a resistor of 100 kohms. This design is familiar: it’s a low-pass filter. Let’s put the same value on this side and everything happen, well, happens.

Desoldering it, the electric path went along with it, probably damaged by the short. Fortunately, a via was nearby, which also let me replace the 0402-sized resistor by a bigger one.

Putting everything back together, pushing the big button.


And here it is, ready for duty! How many Windows update in six months? :D

And here it is, ready for duty! How many Windows updates in six months? :D

Everything starts fine. The keyboard appears to be dead too. But it’s 15$ on eBay so this is no big deal.

Final word: don’t throw your electronic devices… They might be repaired. If you don’t think you can handle it, have a look anyway, go to a makerspace, or give it for free to someone who can fix it. One less piece of garbage contaminating the planet!


The murder’s weapon.

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