Dell XPS 15 9570 capacitor fried

Discussion in 'Dell' started by Desosx, Jul 15, 2019.

  1. Desosx

    Desosx Notebook Guru

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    Hello,
    I bought a Dell XPS 15 9570 refurbished from an ebay reseller partner with Dell.
    This laptop always had some overheating problems (idle temperature was 50-60 degrees) with spike of 90 degrees when simply installing programs. I kept this laptop because it might happen that after a clean installation of windows due to the heavy installation of programs in the background, the pc was always doing system and never in full "idle", and also because I softened this problem using throttlestop.
    Yesterday I restarted the pc in order to install windows updates and I see smoke coming from the pc. I immediately unplugged the pc from the AC, and opened the pc to unplug the internal battery.
    By doing this I apparently voided the warranty that I had with this seller, (I will try to contact ebay directly, because I don't think you can send via package a hazardous item like that)
    I'm now thinking... why it happened? Do I try to buy the motherboard only and try to change it and hope for the best, or this can happen again?
     

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  2. Khenglish

    Khenglish Notebook Deity

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    Clean the area up with a tooth brush and rubbing alcohol. It's hard to tell what blew up.

    If a cap blew, just remove the blown cap and run the system as is.

    Usually power FETs blow though, and I'm suspecting that's what happened to your system. Those will need to be not just removed, but also replaced.

    I would not expect a replacement motherboard to have the same failure unless it is common for the model.
     
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  3. Desosx

    Desosx Notebook Guru

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    Ok, I'll do it when I get home, thanks!
    If it is the mosfet, does it make sense to replace it? it might happen again right?

    It shouldn't be common for that model, I searched a bit and the only similar experience was from the previous model but a dog peed on it, and it was not the case for my laptop.
     
  4. Desosx

    Desosx Notebook Guru

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    I cleaned it and this is the result.
    If I connect the AC the motherboard will produce smoke again in the same spot where I cleaned, so I guess it won't turn on.
    What is more probable, that the motherboard was defective or that the AC charger fried my motherboard?
     

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    Last edited: Jul 15, 2019
  5. Khenglish

    Khenglish Notebook Deity

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    There are probably 2 FETs in parallel and only one blew. If you don't replace it then the other is pushing twice as much current as it is supposed to. If there was only one FET, then you can only run on battery, and you can't charge the battery.
     
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  6. Khenglish

    Khenglish Notebook Deity

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    Ok that picture looks bad. I can't even tell what was there. Clean off whatever excess solder you can with an iron, braid, and flux.
     
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  7. Desosx

    Desosx Notebook Guru

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    I don't know if you noticed, but there is also this component at the bottom that has a bubble, and there was a little bit of ash near it.
    Also if I connect the battery the motherboard will produce smoke again.
     

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    Last edited: Jul 15, 2019
  8. Khenglish

    Khenglish Notebook Deity

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    Ah this makes sense.

    That latest pic shows you blew a power FET on one of the CPU phases. This short then drew a ton of current which then blew the AC power FET, which is the first failure you showed me.

    You'll need to remove the blown CPU power FET and make sure all shorts are gone. The CPU FET will need to be replaced.

    This is becoming a lot of work. I do not know what your soldering capability is.

    Also apparently your board's short circuit protection sucks. Stop trying to power it while it is shorted.
     
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  9. Desosx

    Desosx Notebook Guru

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    My soldering capability is almost not existent, I might ask a friend of mine thou.
    Do you think it is worth a try?
     
  10. Khenglish

    Khenglish Notebook Deity

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    Well it's completely dead so you can't make things worse.

    The first step is to remove the shorts. Make sure the CPU output voltage and AC power in are not shorted to GND.
     
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