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Laptop LCD repair. INVERTER or BL ?

Discussion in 'Electronic Repair' started by Ben, Jun 11, 2007.

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  1. Ben

    Ben Guest

    Hi ,

    Having a laptop with a suspected bad backlight or Inverter.

    I had changed the BL but still no display. Can see the image on the screen
    with a flashlight but the BL doesn't lit.

    How can I confirm if the Inverter is OK ?

    What is the voltage that I should read at the BL input ?

    I have a scope if required.

  2. Bob Shuman

    Bob Shuman Guest

    Usually 5V, but it may vary and you provide no make and model number. Good

  3. mike

    mike Guest

    If you changed the backlight, what's left besides the inverter?
    I'm gonna guess that the liklihood of an inverter failure is
    MUCH greater than the liklihood of failed logic driving it.
    Unless you have access to a high voltage probe, the backlight
    voltage will be well in excess of the rating on most normal scope
    probes. And if the new backlight is not lit, you can suspect that
    the voltage ain't present. You can wave your scope probe around
    over the backlight inverter transformer and tell if it's running.
    There's often a cap in series with the backlight that can go open.
    There's sometimes a fuse on the inverter board. Sometimes, they
    go open for no reason.
  4. Ben

    Ben Guest

    I have a high voltage probe. What should be the voltage ~ ?

    Is a meter in AC mode (1kV) can see something or is too high ?

    I also suspect that the BL taht I changed was maybe bad. Near the contact
    pin on one side , I saw a very small piece of glass remove. That is why I
    want to confirm the Inverter before sending the BL for replacement.

    Tks for your help....
  5. mike

    mike Guest

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