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horizontal white lines covering all of the TV screen

Discussion in 'Electronic Repair' started by AliTonto, Jun 13, 2004.

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  1. AliTonto

    AliTonto Guest

    I have this tv that has parallel horizontal white lines that cover the
    whole screen; they are spaced apart for most of the screen but get
    closer together up the top. I have replaced electrolytics in vertical
    section but no change.
    Whatelse could be causing this problem?
    Any info will be helpful.
    Thank you.
     
  2. john

    john Guest

    Try the scan circuits...If we had the Make and Model
    we could be more helpful.

    kip
     
  3. Sounds like what you're seeing are "retrace lines," which means the raster
    could be turned up too high. See if adjusting the SCREEN control on or near
    the flyback helps a little. In effect, you're turning down the master
    brightness.
     
  4. Jim Lazzaro

    Jim Lazzaro Guest

    I beleive the vertical chip could be faulty.Have you checked Vcc?
    Jim
     
  5. AliTonto

    AliTonto Guest

    Hi John
    The is part of an alarm clock radio Superstar Model and the board
    description is PB1001-H(Rev.3)
    I can identify the vertical chip AN5151N. If this is a possible
    suspect, could anyone give me the pinouts please.
    Thank you.
    AT
     
  6. BWL

    BWL Guest

    Low 200v to the CRT will cause this as well; could be an open or changed value
    resistor in the 200 volt circuit, usually powered by a winding/diode/filter cap
    off the flyback transformer.
     
  7. Mr TUBEAMPS

    Mr TUBEAMPS Guest

    thay are retrace lines, nothing to do with
    the vetical chip.
     
  8. I had similar symptoms with my TV. Turned out to be a cold solder on a diode
    that was part of the power circuit. It used to display this screen just
    before it cut out.
     
  9. AliTonto

    AliTonto Guest

    Yes, I think investigating the crt PCB further sounds hopefull; I will
    check and return my results.
    Thanks to all.
     
  10. AliTonto

    AliTonto Guest

    I have checked voltage to crt and it is at 262v.(I don't have specs)
    I have replaced the diode feeding this which measured rather leaky.
    I have now a better picture which looks normal at the top 1/5 of the
    screen and from there dounwards the picture streches out more and more
    into thin white horizontal lines.
    Any further advice on what the problem could be? I will be happy to
    solve this and maybe someone has the answer.
    Thanking You.
     
  11. AliTonto

    AliTonto Guest

    I have checked voltage to crt and it is at 262v.(I don't have specs)
    I have replaced the diode feeding this which measured rather leaky.
    I have now a better picture which looks normal at the top 1/5 of the
    screen and from there dounwards the picture streches out more and more
    into thin white horizontal lines.
    Any further advice on what the problem could be? I will be happy to
    solve this and maybe someone has the answer.
    Thanking You.
     
  12. BWL

    BWL Guest

    If by normal you mean the top 1/5 of the screen has a normal looking picture,
    which then gets stretched further and further open as the image travels down
    the screen, then your problem now is in the vertical circuit; probably a bad
    capacitor, low voltage to the IC, or bad IC...
     
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