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laptop lcd, inverter,backlight,mother brd, cable,slp switch all ok but bump, it goes dark

Discussion in 'Electronic Repair' started by davidlaska, Mar 5, 2007.

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  1. davidlaska

    davidlaska Guest

    All ok as stated in subject and external crt works fine while lcd will
    go dark (still see the stuff as if the backlight died) if bumped. Do
    not bump for hours, it works for hours. So I am left with some chip
    or such on the lcd board gone bad. But why does a bump put it out?
    It is not like wacking a tv set with cold crude solfer joints?
    compaq presario 1500
     
  2. Meat Plow

    Meat Plow Guest

    Could be a solder joint. Could be a poor connection. Could be anything.
     
  3. davidlaska

    davidlaska Guest

    I have the skill level of changing a few backlights on macs. Is there
    any approach I could take for further trouble shooting (mechanical and
    visual inceptions in particular)? I assume that the LCD solder joints
    fail at times since I have seen others with the exact same problem and
    computer.
     
  4. Meat Plow

    Meat Plow Guest

    Ideally you would want to be able to lay the device out where you have
    access to all the components and give it a good inspection under
    magnification with lots of light looking for anything loose, poorly
    soldered or cracked. Another thing that would be ideal would be where you
    could power it up while it's laid out and tap around on the board(s) etc..
    What would be helpful would be to be able to tap on it to get it to go out
    and come back on. Hope you figure it out, it may take time and you'll
    learn some valuable techniques in doing so.
     
  5. Jack

    Jack Guest

    I have come accross several LCD's that have one end of the CCFL tube wire
    come loose. The solder has turned into very brittle material and resoldering
    these has cured the problem.

    JMK
     
  6. davidlaska

    davidlaska Guest

    I will do visual stuff. I instinctively did bump it back on.
    Rechecking the cable is very time-consuming. If I can find the
    assembly for cheap, I might go that route. Since the external monitor
    works, I can say that the problem lies within the top half of the
    laptop?
     
  7. davidlaska

    davidlaska Guest

    One last question, since the lcd does show data but it is the
    backlight that goes, can I confine my research to that only?
    (inverter, cable, light)
     
  8. Meat Plow

    Meat Plow Guest

    Yes.
     
  9. Meat Plow

    Meat Plow Guest

    More than likely
     
  10. davidlaska

    davidlaska Guest

    You guys have helped to narrow down the problem to cable between lcd
    and inverter, and the inverter and CCFL tube. Before I commit to an
    inverter, I like to find out if a screen that goes black and come back
    in a cold or warm restart, is one the symptoms of a bad inverter.
    I am down to two choices because if I go inside, I might as well put a
    new CCFL in due to its age.
     
  11. Meat Plow

    Meat Plow Guest

    Why not just shotgun it if the cost doesn't prohibit?
     
  12. davidlaska

    davidlaska Guest

    I am not sure what you mean unless you are saying that the computer is
    almost worthless. I looked on ebay after you mentioned cost and
    realized that a 14" compaq presario 1500 with 250mb or ram and 30 gig
    hd and pent 4 processor like mine sells under two hundred dollars.
    So it is not so much the money now, but the idea of spending close to
    that price on Ebay. ( i have purchased over five laptops throughout
    the years on ebay and it has been smoooth ).

    Is there a place one can find particular quarks about specific
    laptops? Issues that do not make a recall list but should have?
     
  13. JW

    JW Guest

    Pretty much, but there is also a signal from the panel controller that
    functions as an on/off signal for the inverter, and usually +12V is
    delivered to the inverter from the panel controller as well.
     
  14. Meat Plow

    Meat Plow Guest

    I didn't mean your laptop was worthless. What I meant was that if the
    ccfl and inverter weren't a lot of money to just go ahead and replace them\.
     
  15. davidlaska

    davidlaska Guest

    I do seem to be dilly dallying around here. I would have jumped on
    your light and inverter solution if I had not read about the same
    problem and same computer someone else had. They did not get the
    problem solved, even with an additional wiring harness.
    Here is the source to keep me honest (I could have interpreted things
    in error)

    http://www.laptoprepairguy.com/lapt...shoot-fix-laptop-video-problems/all-comments/

    comment 163

    Thanks again, my laptop is worth about 200 dollars, almost not worth a
    major repair if it should come up.
     
  16. Meat Plow

    Meat Plow Guest

    That's why I suggested shotgunning the ccfl inverter and harness.
     
  17. davidlaska

    davidlaska Guest

    Something bad happened on top of all that, I bought a new memory
    module and it only shows half the capacity.

    So I am not happy about this laptop today.
     
  18. davidlaska

    davidlaska Guest

    The shotgun idea reminds be of a old laptop I had. I tried to get out
    my frustration by peeling all the layers of the 12 inch lcd screen.
    The last part was impossible, the two thin sheets of glass stuck to
    each other. The best I have done is one inch by three inch tiny
    display from a exercise machine.
     
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