02/01/2010, 02:55 PM
A friend has given me an old laptop to have a look at. It died a few months back. Just out of the blue stopped POSTing, just sitting there with the fan spinning and a blank screen. He's since bought a very nice MSI U100 so it's not a huge loss.
I said I'd have a look at it just to see if there was anything obviously wrong with it like dead RAM or a loose connection. I've gutted it and taken it right back to the circuit boards. I've had them out on the desk with only the bare minimum required for it to POST (1 stick of RAM, tries both sticks in both slots) and nothing else. Nothing's happening.
Looking at the way the laptop is put together I think I might have found the problem. On the southbridge is a small aluminium heatsink. On the bottom cover of the laptop is a vent to allow air to be moved over this heatsink by the CPU fan inlet. However, over the inside of the bottom cover is foil shielding... which blocks the vent.
What I think may have happened is either the chip is dead, in which case there's nothing that can be done or it's suffered a fate similar to many thousands of XBOX 360's. Because of inadequate cooling the solder joints between the chip and the board may have cracked. The classic fix for this is to use a heat gun to melt and reflow the solder fixing the cracks. I however don't have a heat gun so this is what I propose:
Strip the board of everything that can be stripped easily including the cooler, processor, cards and RAM. I could even desloder the larger capacitors making a note of their locations and values for re-soldering afterwards. Next I wrap the board in old cotton t-shirts leaving the southbridge exposed. Then a layer of foil over the t-shirts to stop them from burning. It's then held together with wire. Preheat the oven, yes, the oven to 250°C, higher than the melting point of lead-free solder, and put it in for about 10 minutes. Take it out, leave it to cool, put everything back on and test. If it doesn't work try it again for longer.
So, what does the \/oid think? Batshit insane or do you think there's a small chance that this insane plan might work?
I said I'd have a look at it just to see if there was anything obviously wrong with it like dead RAM or a loose connection. I've gutted it and taken it right back to the circuit boards. I've had them out on the desk with only the bare minimum required for it to POST (1 stick of RAM, tries both sticks in both slots) and nothing else. Nothing's happening.
Looking at the way the laptop is put together I think I might have found the problem. On the southbridge is a small aluminium heatsink. On the bottom cover of the laptop is a vent to allow air to be moved over this heatsink by the CPU fan inlet. However, over the inside of the bottom cover is foil shielding... which blocks the vent.
What I think may have happened is either the chip is dead, in which case there's nothing that can be done or it's suffered a fate similar to many thousands of XBOX 360's. Because of inadequate cooling the solder joints between the chip and the board may have cracked. The classic fix for this is to use a heat gun to melt and reflow the solder fixing the cracks. I however don't have a heat gun so this is what I propose:
Strip the board of everything that can be stripped easily including the cooler, processor, cards and RAM. I could even desloder the larger capacitors making a note of their locations and values for re-soldering afterwards. Next I wrap the board in old cotton t-shirts leaving the southbridge exposed. Then a layer of foil over the t-shirts to stop them from burning. It's then held together with wire. Preheat the oven, yes, the oven to 250°C, higher than the melting point of lead-free solder, and put it in for about 10 minutes. Take it out, leave it to cool, put everything back on and test. If it doesn't work try it again for longer.
So, what does the \/oid think? Batshit insane or do you think there's a small chance that this insane plan might work?
