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Monitor horisontal lines(CRT)

Discussion in 'General Electronics Chat' started by Nicholas, Oct 8, 2007.

  1. Nicholas

    Thread Starter AAC Fanatic!

    Mar 24, 2005
    Hey all!

    I just got a heads-up that the forum miss me:)

    I have a 29" Sony monitor that have horisontal(almost) lines. It looks somewhat like interference, but these are rock solid and very askew, from lower left to upper right. They are on all sources(RGBHV, Y/C and comp.)

    They seem to have gotten worse over time, BUT as the set runs for some time, they get a little better. About a year ago they would go completely(almost) away after 40minutes or so.

    What could cause this problem? Tired caps?

    The set has a detachable input module with it's own power-supply, but
    everything looks fine(to my eyes)


  2. beenthere

    Retired Moderator

    Apr 20, 2004
    Those are retrace lines. The monitor should have blanked them into invisibility, but something isn't quite right. It may be that a solder joint has come open, or that a transistor is getting ready to let the factory smoke out.

    Hard to tell what to do without a schematic to show where to start looking. Too many lethal voltages to just idly poke around without guidance.
  3. Gadget

    Distinguished Member

    Jan 10, 2006
    True, and most flyback problems tend to come from those high voltage stages. It may be anything from A1/G1/Screen volts adjustment, faulty LOP transformer, focus/screen voltage divider network, faulty video output transitors/I.C's or even a faulty picture tube.
    Retrace lines are fine lines widely spaced apart that go across the screen with a slight upward diagonal, and normally are a sign that the Picture tube is not being biased correctly. Sometimes there may be a colour cast involved as well.