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Displays Fixing a Broken LCD Backlight (Benq FP937S+)

Discussion in 'Tech Support' started by oasked, 25 Sep 2010.

  1. oasked

    oasked Stuck in the Mud

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    Hi guys,

    My old BenQ FP937S+ broke about 6 months ago - the backlight died, meaning that the display is effectively useless as you can no longer see anything on the screen (you can very, very faintly see the start-up logo in good light).

    I heard that it was unlikely to be the backlight itself that had broken, but much more likely that one of the capacitors that powered the backlight had blown. So, now that I've got some free time I have completely disassembled the monitor and I've found the circuitry where this faulty capacitor should be.... and disconnected it from the Samsung panel.

    The trouble is - I can't find any capacitors that are obviously blown, bulging or leaking - has anyone got any ideas? Below are pictures of the circuitry, any help or ideas would be greatfully appreciated. Or if you have any other suggestions to save this screen from the bin!

    Thanks guys! :)

    [​IMG] [​IMG] [​IMG] [​IMG]
     
  2. RichCreedy

    RichCreedy Hey What Who

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    thats just pants, you have a 4 way inververter built into a powerboard, it would have been easier if you could just try a new 4 way inverter.

    non of those caps have obviously blown

    have you checked for dry joints?
     
  3. oasked

    oasked Stuck in the Mud

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    Nope, but I'll have a look now - thanks for the suggestion.

    (A dry joint is this) apparently...

    EDIT: Had a quick look, and no obvious visible sign of any dry joints... I think the screen may be heading toward the bin. :(
     
    Last edited: 26 Sep 2010
  4. RichCreedy

    RichCreedy Hey What Who

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    google the powerboard part number, maybe you will be able to find one, also type part number in this website
     
  5. capnPedro

    capnPedro Hacker. Maker. Engineer.

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    From a quick look on Google it seems like one or two of the transistors may have burned out (collector-emitter will show as a dead short).

    You can replace it/them, but it'll probably burn out again. One theory is that the voltage rating on the capacitors is too low, so you'd need to replace them all too. But the reason stuff went wrong in the first place (without a burn capacitor) may suggest that you have a short in one of the transformers. Which would be a pain to discover.

    The monitor design is apparently not very good!

    How much free space is there? If I were going to fix it, I'd just make/buy a separate PSU for the backlight and hack it in.
     
  6. oasked

    oasked Stuck in the Mud

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    Cheers for the info guys, looks like its going to be a pain to fix! I bought a replacement monitor for my folks a few months ago so I think I'll just be dumping this one - as the fix sounds a bit like a wild goose chase. :)
     

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