Tuesday, April 19, 2011

Acer 17.3" Shuts off when moved or touched

Newer Acer 17" Model [7736Z-4809] laptop arrives after being repaired.  



The initial repair was a DC jack. Seems that the jack didn't last long and was sold to a reseller. Physically broken and replaced.  

After replacement, the unit would charge and run.  Minor tests completed based upon user diagnosis.  However, if the laptop was moved when on/running, it would shut off immediately, and the lights would go off. (Charge and Run lights).




 When the unit was moved or tapped at the area on the right where logo stickers are, it would shut off -everytime. Thinking it may have been a ground issue with the case, I tapped the motherboard after it was removed, and still presented the same problem.  Repeated on/off testing located the area where the open circuit was occuring.  The PCI controller chip (indicated in square).  Since this model did not use high temp glue to hold the chip to the motherboard, the best reflow method for this model would be Low Temp reflow with liquid flux instead of the petroleum based flux.



Why? Because if the chip is having issues with the solderballs too much heat would separate the chip from the board, requiring reball or motherboard replacement. A High Temp reflow would cause that problem. And there would be no way to rescue it at this shop. So that is why low-temp reflow method was used. 



A low temp reflow involves liquid flux, and heating only half the chip at one time. First the lower half, then allowing it to cool a little, then the top half.  This method assures that the chip does not become unseated, as well as preventing solder balls pooling together and shorting out. The liquid flux aids in bonding the solderballs to the motherboard as well as removing oxidation (not much at low temp).

8 comments:

  1. After some reflows, i get the problem with turn on/shutdown. What can be causing that, shorts or maybe bad flexcable? Had problem with Dv9000 and dell

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  2. You may be overheating and the solder is pooling together. Into small puddles causing shorts, or it may be an underlying issue. You can retry a reflow process on a level surface with liquid flux. No guarantee but it may work.

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  3. Hi Mayo, any news on the video and the kit.
    Chow Mike

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  4. Its in Post Process and editing. Having a friend do it so that I have time to do other things

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  5. Ok cool enjoy your other things.

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  6. Ok i will try that. What do you do with all that epoxy that is around gpus etc? Do you remove it, or will it melt during reflow? How do you remove it.

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  7. P: This one did not have epoxy around the southbridge, that may have came in later units after the problem was recognized. In that case you can heat the epoxy and remove it with an awl, scraping with the point sideways, not downward. This way only the epoxy is touched and not the motherboard. Caution is advised it you need to do that.

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  8. hi i'm french sorry for language i have a probleme the dc jack is ok but i haven't light the battery and the transfo is ok
    why the link of the video is failied

    thx

    ReplyDelete

I cannot repair laptops for you via the internet, I can only answer questions related to posts. This is because I have not had experience on every motherboard that is out there. Bear with me.

If you do need it repaired. Contact me for quote (US/CDN Only)

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