Thursday, August 16, 2012

How to (unsucessfully) reflow the solder on a motherboard

The HDD in my 7 year old laptop died recently.  Todd was nice enough to give me 2 old laptops he had laying around, one of which was much nicer than the one I had been using.  The catch was that neither of them worked.  I managed to salvage the HDD from the one, and put it in my laptop, which is now going strong for another 7 years.

The other laptop was a HP Pavilion dv6000.  When I turned it on the lights came on, but nothing else, no beeps or screen output, then it began to cycle endlessly.  It turns out this is a common problem with that model, due to faulty solders.  There had been much success online with people fixing this by heating the motherboard up hot enough to melt the solder and let it reflow.  As I had my other laptop working, and nothing to lose I decided to try it.

My first step was to disassemble the laptop gradually over a few days without following any guide or taking any pictures.  While taking it apart I kept noting how there was no way I would remember how to reassemble this thing, but I never let that distract me.  Once I had the motherboard removed, I had to remove everything that could possibly be removed.  Of particular importance were the motherboard battery and paper stickers.

Eventually, I had the bare board.  I decided to use my toaster oven as my regular oven is gas, and there seemed to be concern about airflow moving tiny components around while the solder was liquid.  I also read it was a good idea to cover most of the board in tin foil and only expose the parts you want to reflow.  I didn't do this, because there was no tin foil in the first place I looked.  One helpful tip I found online was to put a piece of solder on one of the exposed screw-in pads, and place that where you can watch it.  This serves as a useful temperature monitor.  I put a piece on each forward corner.

I placed it in the toaster oven and set it to toast at 400F.  It only took about 5 minutes for the one piece of solder to melt, however, the other piece remained solid for a minute longer.  I let it sit molten for about 5 minutes, and then shut it off.  Right after I shut it off I heard a lot of crackling sounds.  I suspect this might have been due to the board cooling very fast in the toaster oven, as opposed to a real oven that would have cooled much more gradually.

I let it sit for 30 minutes and then opened the door and let it sit for about 10 more.  I removed it and nothing seemed like it had burst into flames or exploded.  When I lifted the board up I noticed some solder on the pan, in a splatter like pattern.  I also noticed a tiny component that had fallen off.  I tried to match up where the part was and what part of the motherboard had been above it.  I spent about 5 minutes trying to find a spot it could have came from, but to no avail, not that there was any hope I was going to resolder this flea sized thing back on even if I did know where it came from.

Still, I figured it was possible that it would still work without it.  After all, the tinier something is the less important it is, right?

I reassembled the laptop only as far as I figured it would need to be to get any sort of screen output.  I put in the CPU and RAM and connected the power and power button connector.  I pluged it in and turned it on... and... it did the exact same thing as before.  I was somewhat surprised, with that missing part, but then again I guess if the solders were already bad then a missing part was pretty much the same thing.  I guess I should have flashed the bios instead.

I didn't really care, as I had already gotten my laptop working and spent days researching Linux and setting everything up.  But here are some protips for anyone else that may be trying this and actually wants to succeed:
  • I think I should have used the regular oven instead of the toaster oven.  Even with the gas, I don't think it would be a problem, and I think the fast cooling of the toaster oven was worse.  Also, the fact that the two test pieces of solder melted at different times told me that it wasn't a very even heating.

  • I probably should have wrapped the board in tin foil.  Perhaps this would have helped keep that other random part from falling off.

  • I definitely should have opened windows from the start.

  • There was red glue of some sort around the solders on the chipset.  Someone mentioned that you should carefully remove this.  That was probably good advice because it was charred black.

1 comment:

  1. This is a great post for a lot of reasons. I love the lengthy self-depricating posts, especially if someone actually stumbles upon this looking for the real solution. Also the flash the BIOS inside joke.