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Sony G400 CRT problem identification ...

Discussion in 'Electronic Repair' started by erik vogan, Oct 21, 2004.

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  1. erik vogan

    erik vogan Guest

    Hello,

    I am hoping that someone can help me identify the problem(s) with
    a Sony G400 19" CRT that I recently was given. After connecting and
    powering on the G400, the display showed these symptoms:

    1) The picture was far too bright. Black displays as a light gray.
    Adjusting the brightness through the onscreen menu makes no
    difference.

    2) Vertical retrace lines are clearly visible (white or very light
    gray) as a zig zag pattern. From the bottom left of the monitor a
    line will go diagonally to about an inch above the bottom on the
    right, then go straight back to the left side, etc. Repeats about
    twelve times. The retrace lines get closer together as they get to
    the top of the monitor.

    3) There are very bright lines on both edges of the picture. If I
    reduce the horizontal picture size (by decreasing the horizontal size
    in the onscreen menu), the bright lines move with the picture. Could
    these be the horizontal retrace lines ?

    4) The display seems a bit fuzzy. Text is hard to read at 1280x1024
    on a monitor that should support 1600x1200. This could easily be due
    to point 1), but I decided to mention it in case it is a important
    detail.

    5) All of the onscreen menu options work, with the exception of the
    horizontal position slider. Varying that slider does not change the
    picture in any way. The vertical position slider does work, as do both
    horizontal and vertical size sliders.

    6) Leaving the monitor on for 45 minutes did not improve any of the
    symptoms.


    After reading the Monitor repair FAQ (
    http://repairfaq.ece.drexel.edu/sam/monfaq.htm ), I think that this is
    probably a failure of the blanking system (misadjustment, a power
    supply or connection issue, or a failure of the blanking circuit).
    However I can't find a mention of anything like 5) in the FAQ (which
    could be due more to reader error rather than absence of the
    information), and I think it is probably telling me something
    important.

    Has anyone seen these symptoms, either alone or together ? I am
    fairly certain that 1) to 4) form a group caused by a single defect,
    but I hope that 1) to 5) can narrow the failed (loose) or misadjusted
    component a bit more. Can anyone tell me how best to proceed with an
    attempted repair on this monitor ? In addition, I don't know how long
    the monitor has been in this state. Is there likely to be permenant
    damage if the monitor was run this way for an extended period of time
    ?

    Thanks very much for any help or suggestions.
     
  2. Wayne

    Wayne Guest

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