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Notebooks Black screen on laptop

Discussion in 'Tech Support' started by HandMadeAndroid, 24 Sep 2015.

  1. HandMadeAndroid

    HandMadeAndroid That's handy.

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    I own a w170HR with an LCD screen. One day when I was outside the screen stopped working. I presumed it was a broken screen so I got a replacement. This was because everything works fine when plugged into an external monitor.

    The replacement arrived today so I dismantle the machine and replace the panel. I start it up and the screen is still black. I plug in the external monitor and there's two monitors present in the device manager (win8) The can even see the ID of the new panel under it's properties.

    What the dickens is going on? Could the replacement screen be dicky too or is there something I'm missing. I've tried everything, taking the battery out, holding the power switch down, botting with one stick of ram, etc.

    Thanks in advance for any help
     
  2. blackerthanblack

    blackerthanblack Minimodder

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    I've not checked your model but it could be a couple of things -
    It could be the backlight/invertor - there would still be a very faint image on the screen if you look carefully.
    It could also be the connection between the video card and the screen - the external output would be unaffected by this.
     
  3. glendronach

    glendronach What's a Dremel?

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    It could be the lid switch or if it is an LED backlight, loss of power to the LEDs due to anything from a faulty ribbon cable to a blown fuse link.
    Older screens used CCFL tubes and power inverters to supply the backlight but an internet search suggests that Clevo model is LED.
     
  4. HandMadeAndroid

    HandMadeAndroid That's handy.

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    Hey thanks Glen and Black for taking the time to answer. Firstly the second reply is correct, it is indeed an LED without inverter.

    I'm originally from the UK, but now in Brazil, so this is bit of a problem to repair. We're going to try taking it to a maintenance place. Are the faults you mentioned such as a blown fuse link expensive to repair? Like I said in earlier post, everything works fine through a external monitor so I doubt it's anything on the board.
     
  5. Yadda

    Yadda Minimodder

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    Glen, I have exactly the same problem as the OP and have tried a new VGA cable and a new panel to no avail. My thread is here: http://forums.bit-tech.net/showthread.php?t=283048

    I hadn't considered the lid switch until I read your post, what do they look like? (I thought I'd found it but it was the Bluetooth module).
     
  6. HandMadeAndroid

    HandMadeAndroid That's handy.

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    I think my switch works based on closing the lid puts the machine to sleep.
     
  7. Yadda

    Yadda Minimodder

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    Sure, that's what it does. I need help IDing the switch/sensor location. I've googled around and from what I can see, it's often a removable "reed switch" module located around the touchpad area underneath the palm rest. I stripped my laptop down and had a look but the only module i could see in that area was for Bluetooth.
     
  8. HandMadeAndroid

    HandMadeAndroid That's handy.

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    simple to find location, just get something metalic (I used the wifes tweezers) and move it over the surface until it sticks to something!
     
  9. Yadda

    Yadda Minimodder

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    Tried that. No luck unfortunately. Figured it must be a very weak magnet, too weak to easily detect.

    I did manage to get it into suspend/sleep mode though (blinking power light and TV screen went black), by waving a strong magnet underneath the laptop, around the touchpad area (taking care not to go anywhere near the HDD!). It woke up when I pressed the power button but still nothing on the laptop's own screen.

    I'm thoroughly stumped!

    Edit: I have found the laptop's embedded magnet. It's on the screen bezel which I'd left detached after replacing the panel. Anyway, when the lid's closed, the embedded magnet lines up with a small square surface mounted component on the motherboard which isn't removable. However, since I was able to put the laptop into sleep/suspend mode by waving a magnet around, I'm now not sure that the switch is what's causing my problem because it's clearly doing something. My prime suspect is now the f1 fuse (thanks again Glen, I would never had suspected a fuse). Time to break out the multimeter and soldering iron. Gulp.
     
    Last edited: 25 Sep 2015

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