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Sony Trinitron brightness problems or old age?

Discussion in 'Electronic Repair' started by Wayne Peacock, Jun 17, 2004.

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  1. Hi all,

    I have a sun GDM-5010PT 21' monitor that I have just fixed the power
    supply for. Now the brightness is very dim and I need to up the screen
    or sub-brightness. And yes the power supply rails all test OK.

    I am aware there are no trimpots and most settings are controlled by
    software (DAS from what has been listed in this group). How can I
    increase the brightness without the software or would someone have the
    protocol for the serial connection?

    I am very capable of writing a program and wiring a cable for this if I
    know what to write to the monitor. Can a resistor be changed etc?

    What is the normal life of a trinitron tube? This monitor was made in
    march 1998 and has likely been on for it's life. Could it be on it's
    last legs

    Thanks
    Wayne Peacock
     
  2. Brightness half-life of a typical CRT is usually quoted as 15-20K hours.
    If it's really been on for 5 years continuous without full power saving
    mode implemented, could indeed just be a tired CRT.

    Is there not even a screen/G2 pot on the flyback?

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  3. Continuous with power saving. I would assume a normal day in the office!
    7 hours per day etc. 'Typical life of CRT' is that the same as a
    trinitron? or are trinitrons different.
    There are two adjustments on the flyback. But posts in the forums state
    them as H & V focus? I have tried adjusting both and they just change
    the focus.

    Regards
    Wayne
     
  4. Continuous with power saving. I would assume a normal day in the office!
    More or less, they are the same.

    Trinitron tubes employ a different electron gun design than conventional
    picture tubes as well as employ an aperture grille instead of a shadow mask.

    But, Trinitron tubes are still cathode ray tubes. This means that the electron
    guns will wear out through use in about the same amount of time as any other
    picture tube, give or take a few years. A benefit could be that Trinitrons are
    more efficient because of the aperture grille, but that doesn't change the
    aforementioned fact.
    Unusual, but there have been stranger things.

    There should still be a way to adjust the voltage level going to the picture
    tube from the flyback.

    However, continuous operation for over five years, even with power saving, may
    wear out a picture tube. You may have to consider installing a CRT booster. -
    Reinhart
     
  5. Nigel

    Nigel Guest

    If it's anything like some Sony TVs, you might want to check the value of
    the resistors on the tube base before consigning the whole thing to the
    scrapheap. Do cold checks on anything above 100K to see if the values have
    drifted - I've had plenty that do, causing picture effects not dis-similar
    to tube wear. Of course, this doesn't negate the other useful responses
    you've had thus far.
     
  6. Wild Bill

    Wild Bill Guest

    I think the only kludge/last ditch effort I've heard of for getting a little
    more life from a dim display was to look for a series resistor in the
    filament/heater circuit (and lowering it's value slightly).
    This might not be a viable fix on these newer models.

    Cheers
    WB
    ................
     
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