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Looking for guidance on CRT TV repair

Discussion in 'General Electronics Discussion' started by oarment2, Feb 20, 2021.

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  1. oarment2

    oarment2

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    Feb 20, 2021
    Hello,

    I recently got a CRT TV (Sony KV-29FA515) that has some picture issues. I got it for the equivalent of USD $10, with the purpose of using it to learn how to fix it and then use it for retro gaming.

    I'm looking for some guidance on how to fix it, I enclose a couple of pictures of the issue and the model information for the CRT.

    Audio works perfectly, the issue is with the image itself, I get three colored lines (red, green and blue) and several white lines at the top of the screen.

    I'd appreciate any guidance on how to troubleshoot or what circuits or component damage to look for this specific issue.

    Thanks!
     

    Attached Files:

  2. bertus

    bertus Moderator

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    Nov 8, 2019
  3. AnalogKid

    AnalogKid

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    Jun 10, 2015
    The three beams sweep horizontally very quickly while they sweep vertically relatively slowly. When they reach the bottom of the screen, then are blanked( turned off) and yanked back to the top of the screen quickly, during the "vertical blanking interval". So rather than zig-zag downward slowly, they zig-zag upwards quickly. If the vertical blanking ends too soon, you see the last few sweeps at the end of the rapid upwards zig-zags before the beams reach the top of the screen.

    If you can find the schematic online, post a link. Vertical blanking control probably is buried inside a syng processing chip, but there might be an external timing capacitor that has changed value over time.

    ak
     
  4. bertus

    bertus Moderator

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    Nov 8, 2019
  5. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Looks like the vertical blanking might be adjustable through the remote control.

    ak
     
  6. oarment2

    oarment2

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    Feb 20, 2021
    Thanks for the guidance, I just got a replacement remote and looking at the service manual for those adjustments. I'll keep you posted
     
  7. oarment2

    oarment2

    3
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    Feb 20, 2021
    Hi Everyone, I apologize for taking so long to respond, it's been really busy lately.
    I was finally able to play with some of the settings in the service adjustment mode on the TV.
    By adjusting the VPW setting I was able to push those flyback lines to the very top of the screen. This pretty much solves my issue, however, I will keep going through the adjustments to try to completely remove them.

    Thank you all for the assistance!
    20210228_104314 (1).jpg 20210228_105339 (1).jpg
     
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