1/3rd of screen black with occasional vertical lines - repair attempt for learning! - Kogan KALED58RT9220SVA

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  • Firentiosi
    Hobbyist
    • May 2021
    • 5
    • UK
    #1

    1/3rd of screen black with occasional vertical lines - repair attempt for learning! - Kogan KALED58RT9220SVA

    Thanks for offering your assistance with this. I'm an electronics enthusiast with moderate level of competence (have a decent lab with two power supplies, microscope, DSO, hot air, good iron, can competently work at a component level on SMDs, design and solder own PCBs etc). I really enjoying fixing things and learning new stuff so took up a free 58" LED TV and have been googling and watching Youtube videos to see if I can fix this! I am happy to go down to individual component replacement/strip replacement etc - it's all in the name of learning.

    The issues are as follows: the left-hand 1/3rd of the screen is black, no image and occasionally has vertical multicoloured lines. The backlight is functioning on the TV and shining a flashlight doesn't show any image.

    The circuitry has a power supply unit and a TCON board (CHOT CV580U1)
    Voltages measured are as follows:

    12Vin - 12.49V
    VBo 0.03V
    VSS1 7V
    RVAA 15V
    LVAA 15V
    VGHF 7.7V
    VGL -8.8V

    There are also 1.2V, 3.3V, 12V and 15V DC power rails present.

    The TCON board connects to a LEFT and a RIGHT sub-panels. Each sub panel has multiple connections (chip-on-film, I believe) to the panel/LED circuitry. If a third of the screen is not working, then perhaps it is something to do with a short or open circuit 'upstream' of the three COF strips that feed the leftmost third of the board?

    I have attempted to unseat and reseat the mainboard -> TCON board ribbon strip and TCON--> sub-panel ribbon strips.


    1. How can one tell if it is the LED strips themselves vs another component? I see that these strips are usually arranged horizontally, but my issue is a vertical one. Perhaps I am naively thinking that it is not the actual LEDs?


    Any further information or troubleshooting greatly appreciated.
    2 Photos
    Tags: None
    • Firentiosi
      Hobbyist
      • May 2021
      • 5
      • UK
      #2
      Ah, found it. Crack in the LCD right where I'd expect it. Thanks anyway guys.

        Comment

        • KYBOSH
          Badcaps Veteran
          • Oct 2011
          • 581
          • Unknown
          #3
          For me... vertical lines means "dont bother"
          Usually a tab bond issue and not really a crack in the screen.
          But you can learn from this TV set.
          Its a junker but you can have a look around to get a feel of what's what.
          So next time you have a set you are trying to save you'll have a better understanding of things.
          Good luck

            Comment

            • Firentiosi
              Hobbyist
              • May 2021
              • 5
              • UK
              #4
              Thank you! Yes, I'd learned as much as I could from this set. Just the basics, but was still informative.

                Comment

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