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Solved: Laptop screen stopped working after cleaning its fan.

Discussion in 'Hardware' started by Qqwy, Jan 13, 2013.

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  1. Qqwy

    Qqwy Thread Starter

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    Hello there, everyone.

    I have a HP Compaq 6720s laptop. This is a laptop that is about six years old. The last two years the fan had been extremely loud. Because I guessed that there might be quite a bit of dust inside of the fan, I decided to open the laptop up and clean the fan.

    This turned out harder than I'd expected, since the fan is on the bottom of the motherboard.
    I used the following video to guide me through the disassembling process: http://www.youtube.com/watch?v=Pxggm5CWnHA

    There indeed was a lot(one could say a carpet made out of) dust inside the fan/heatsink. After I cleaned it I assembled the laptop back again as good as I could. I think I did fine, even tough I somehow ended up with a few screws I must have forgotten somewhere.

    Then I tried booting the laptop. The power light went on, the fan started to spin but the screen kept completely blank.

    As far as I know I've reconnected everything. I rechecked everything and I believe all is fine. The screen seems to be connected to the motherboard through a black and a white cable. (In the video these get disassembled at 6:20). These are connected.

    I tried hooking up an external display to the laptop's VGA port. When powering the laptop it keeps blank as well (giving the stand-by flickering of not recieving input). Then again I'm not sure how external monitors normally react to laptops: if they instantly work or if you have to change some settings in your OS before the computer will send the screen through the VGA.


    My question:
    What might be causing my screen to be black? Is it possible that something on the motherboard is short-circuiting or something because I've opened it? Does it mean something that an external monitor won't work either or is this normal?


    Thanks a lot,

    Qqwy
     
  2. Qqwy

    Qqwy Thread Starter

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    I have been trying some more things. I've again completely opened the laptop up and looked for things that might have short-circuited the motherboard. I've also tried resetting the BIOS by removing/reinserting the battery from the motherboard.

    Still the screen does not get on...

    I also read something about static electricity: Is it possible that I broke my motherboard because I touched it?

    Thanks,

    Qqwy
     
  3. dai

    dai

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    did you redo the paste on the cpu after disturbing the fan

    http://www.arcticsilver.com/methods.html

    you normally need to press one of the F keys that has a tv icon on it to switch to an external monitor
     
  4. Qqwy

    Qqwy Thread Starter

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    Thank you for your reply, daj. I did not replace the heatsink paste, because I didn't touch or move the heatsink. I cleaned the fan and the space between the fan and the 'exhaust' that the heatsink is connected to (not sure how to call it; the part where the air flows through out of the laptop again). The heatsink including this metal grid structure are attached to the motherboard and I did not attempt to unattach them. Could it still be a problem in this case?

    I also tried using the function key with the TV monitor on it by pressing fn + F4 as the function keys on this laptop normally behave. Didn't work. I now also doubt if the computer is actually booting up the operating system, because none of the function keys work, the wireless turn on/off button left of the power switch doesn't react when I press and I do not get any sound(like a startup sound), not even when waiting for ten minutes after turning the computer on.
     
  5. dai

    dai

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    try a cmos reset


    see if it boots into the post screens with both drives removed
     
  6. Qqwy

    Qqwy Thread Starter

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    Removing the hard drive or even both ram slots does not seem to change anything about his behaviour.

    I haven't tried re-flashing the bios or whatever it is that the third post is telling me to do because I sadly do not have an USB floppy drive over here. Would the same steps work with a CD-ROM or not?
     
  7. dai

    dai

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    i don't want you to reflash the bios i meant a cmos reset

    it will not start with the ram removed i was referring to the hard drive and the cd /dvd drive
     
  8. Qqwy

    Qqwy Thread Starter

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    Sorry, I need to get my terminology straight. I now know that a cmos reset is the same thing as removing the bios battery. I did this when I had the laptop opened up the second time.

    So, and now I tried removing the hard drive and CD/DVD drives...


    Wow... when removing the hard drive and the CD/DVD drive the screen will display the boot screen with the HP invent and Intel logos before coming up with an Non-system disk or disk error.

    Then I tried re-inserting the hard drive and the CD/DVD drive. Miraculously the computer booted up completely normally.

    I don't know how booting up without both drives could've worked, but it somehow fixed it.


    Thank you very much for your help!
     
  9. dai

    dai

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    removing and reinserting the drives would have cleaned the contacts on the drives

    a fault with one of the drives could and looks like it was the cause of stopping the boot

    glad you have it sorted
     
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