Haier HL42XD1 dim backlight for a second then no backlight

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  • paulstef
    Badcaps Veteran
    • Dec 2013
    • 724
    • Canada
    #1

    Haier HL42XD1 dim backlight for a second then no backlight

    Does anyone have a true datasheet for the OZ9976? (not the family pdf)

    It puts out pulses to turn on the backlight for a second then stops working. I attached ISENS and VSENS scope screenshots (directly on IC pins). All other voltages are stable.

    Enable voltage: 3.2V seems ok
    PDIM voltage on IC : 1.6V seems ok
    12V power ok
    B+ ok

    I don't know why it stops working . I guess one of the two feedback signals VS or IS is not good. The transformers seem all correct.

    If I suspect a faulty CCFL can I DISCONNECT ONE BY ONE or is it possible to damage the high voltage transformers due to no load by doing this?

    Thanks
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    • paulstef
      Badcaps Veteran
      • Dec 2013
      • 724
      • Canada
      #2
      Re: Haier HL42XD1 dim backlight for a second then no backlight

      I removed the feedback cable and turned the TV on. Saw a sparking in one of the tranformers, measured its secondary, it was open. Shorted its primary, TV works. The missing CCFL is hardly visible.

      Don't know for how long this will work.

      I'm assuming the CCFL is actually faulty since the transformer had the same secondary resistance as all the others.

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