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How to repair a dying laptop with a blowtorch (for real)!

September 19, 2011 1 comment

Well, it was about time I polluted the Internet with my thoughts and actions. So I’ll just cut to the chase.

A friend gave me an old laptop (a HP dv4000) , mostly because it had a problem that made working rather cumbersome.

Every once in a while the laptop froze completely. Not just the screen, but everything. The hard disk stopped, the touchpad and keyboard stopped responding and all usb devices too. Weird enough when I placed the laptop on the workbench, I discovered that if I applied some pressure over the touchpad when the laptop was frozen, almost everything went back to normal. The touchpad, keyboard and HDD started working. The USB devices however well long gone. Unplugging / pluggin again did nothing. For the USB ports to work the laptop had to be rebooted.

At the time I didn’t have much time to look the cause further and thought to keep it as a fallback laptop incase something happened to the main laptop I used. So I threw Windows XP out the window and installed my favorite linux flavor; OpenSUSE 11.4

The other day having nothing to do, I thought to dig in further…

I haven’t look used the laptop since I installed openSUSE on it. So it was time to make use of the linux goodies.
Behaviour was as above. The laptop froze at random times, killing all peripherals. The kernel logs simply reported dazzled and confused when pushing over the touchpad. That was enough to think it was a hardware problem.

So I put my mind to think. What controls all those peripherals? Of course! The southbridge chip. After disassembling several parts of the laptop it was time to dig in.

I located the southbridge chip almost directly below the touchpad. That made sense for the pressure putting things to work again. So after poking around the Internet I found a few other similar cases and went to try for myself.

Things used:

  • Philips screwdriver to take apart the laptop
  • A small blowtorch
  • A K type (thermosensor) thermometer
  • A pair of angled tweezers
  • A 2 Euro coin
  • A lot of patience
  • A bit of luck
  • Optionally: Solder
The point is to heat the coin using the blowtorch to about 210C measured with the thermometer and put on the southbridge chip to transfer heap and allow the BGA solder balls to reflow, fixing our problem.
During the heat transfer process, I was testing by moving the touchpad from time to time, to check when the chip would work properly.
I had several tries at this. 210, 220, 250 degrees. However the temp dropped to quick when putting the coin on the chip to allow to reach the reflow temp. To help the procedure I had the laptop running all the time to provide additional heat to the southbridge chip. Nothing worked though.
After getting pissed of, I decided to do things my way.
I simply placed the coin on the chip, the K type sensor touching it next to it, and started heating the coin while ON the chip. I had several tries at this also. When I’ve had enough, I said to myself: “I’ll either repair it or throw it way”. And so I did.
I was heating and slightly pressing the coin with the tweezers to help “resoldering”. I had to be extremely carefull here because a bit more strength would make the BGA ball stick together and destroy every chance of making the laptop work. I had to heat the coin up to 350C to get the balls to reflow and apply a very light pressure.
After I check the laptop was working fine, I let it cool done WITHOUT removing anything. Just let it cool gradually.
THE RESULT? I got another fully working laptop available at my disposal.
I didn’t record a video of the procedure because I didn’t think of it in time. I took however two pics at the cooling stage, for your pleasure and my bragging. enjoy!
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