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    flaky trackpad on Dell Latitude E7250

    Hi all,
    Does anyone know whether a jumpy/freezing/'flaky' touchpad can be due to a motherboard problem ?

    I have a Dell Latitude E7250 whose motherboard failed, so I bought a damaged-but-working E7250 on eBay, to use its motherboard (Compal LA-A971P) in mine.

    When I received the eBay laptop and first quickly tested it by booting into the BIOS, I noticed that the trackpad cursor movement was intermittently unreliable - the cursor would follow your finger movement for a few seconds, then stop moving, and you would have to take your finger off the trackpad and put it back on again several times before the cursor would start moving again.
    Felt a bit like the way it does when dirt or grease etc preventing reliable contact between finger & trackpad.
    Occasionally it seemed to falsely detect a double-tap, and select/open the item under the mouse cursor. i.e flaky and hard to use

    Not to worry I thought, I don't need the trackpad from the old laptop, just the motherboard.

    But when I put the new motherboard in my old laptop , I was surprised to find the same problem occured - flaky, intermittent mouse movement , both in the BIOS and in Windows 10.
    In the Dell Diagnostics (F12 button) the problem seemed not so frequent, but still present.
    An external USB mouse works fine in BIOS, Diags and Windows.

    I tried swapping out the palmrest/trackpad - no improvement

    I upgraded the BIOS to the latest + tried disabling/re-enabling touchpad in the BIOS options - no improvement

    I also installed Linux on the laptop just to confirm it wasn't a software problem : touchpad flaky in Linux.

    I read online that power/grounding issues might be a problem, so tried it with 3 different Dell and aftermarket power supplies, and with and without a battery.
    Also tried without LAN cable, wifi nor any other external cables/devices connected.
    Also tried multiple combinations of parts from each laptop (screen, chassis, keyboard, palmrest cable etc) in case one of these was causing it - always the same

    Before I give up on this and buy another motherboard to test against (I'm determined to find what is going on here), I thought I would check with you experienced laptop fixers to see if you have any ideas/suggestions

    thanks for any tips,
    Rob

    #2
    Re: flaky trackpad on Dell Latitude E7250

    Update: it turned out that BOTH the trackpads had the same fault.
    (I had briefly considered this possibility when testing , but thought it was very unlikely , as I didn't recall any trackpad problems from the original laptop).

    I'm relieved to find the problem lay in the trackpad after all, and not in the motherboard

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