40H80 Horz Linearity, HOWTO fix?

Discussion in 'Archived Threads 2001-2004' started by Peter S, May 10, 2001.

  1. Peter S

    Peter S Agent

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    About a month ago, my TW40X81 set was replaced with a 40H80. I am gearing up to do a gambit of adjustments to the set, this weekend. However, there is a problem I am unclear how to correct.
    I see this problem when watching CNBC, the channel with the stock quotes scrolling across the bottom of the screen. As a given quote approaches the last 3 inches of the left of the screen, it squishes up.
    Since I own a set of the convergence overlays, I thought I would check out the horizintal linearity. My test source is the Avia "Center Cross" pattern. With the center of the pattern centered to the screen, the problem is real clear. The "over scan" mark on the left side of the pattern is visible, and about 1/2 inch from the edge of the screen. The mark on the right side of the pattern is off the screen about this same distance, 1/2 inch.
    Thus, the left half of the image is narrower than the right half. The LIN parameter sets the Vertical Linearity, which seems to be the property I'd like to adjust, but on the horizontal access, not the vertical. None of the remaining service mode parameters appear to be the ones I need to correect this.
    Does anyone have any ideas?
     
  2. Steve Martin

    Steve Martin Auditioning

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    It sounds like you will have to correct the geometry with the service mode convergence grids. You will want to turn off red and blue and line up the green to the convergence overlays. Then converge red and blue to the green.
    You should do the best you can with the service mode geometry parameters first, but after that you have to bite the bullet and use the grids.
    ------------------
    Steve Martin
    The Widescreen Movie Center
    www.cheezmo.com/wsmc/
     
  3. Peter S

    Peter S Agent

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    Really? Wow, that really bites. To line up the screen with the grid, properly centered, I'd need to increase the left half of the screen nearly 25mm, at the outer egde. The right side of the screen would need a reduction of 20mm. That requires moving each of the ~64 points in and out, in all video modes. I'd rather look in to exchanging the set, before forcing such relatively large geometry changes on the convergence engine.
    The "squishing" of the left side is also noticable in scenes with spaceship, travelling from right to left.
    I thought there was a Horizontal Linearity setting from Desginer mode on my TW40X81. I suspect the same setting exists, but is available from ADDR mode only. Perhaps, I should just sit tight for a while, and see what information surfaces on this issue.
     
  4. JohnnyG

    JohnnyG Screenwriter

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    Yup, there is only a vertical linearity adjustment on this years sets, unfortunately.
     
  5. MickeS

    MickeS Producer

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    Peter, I doubt that replacing the set would help.
    I am thinking of buying it, and I sat at Best Buy watching this set for over an hour yesterday. I did the regular 9 point convergence, I set the picture to MOVIE mode, with contrast and brightness reduced to about 30. I figure that was good enough (?).
    There were some material where text was rolling across the screen just like you describe, and I saw exactly what you describe. It could only be seen with scrolling text (didn't have any test patterns to check), regular pictures seemed fine.
    I told a friend about it just a little while ago, wondering if this was something specific about this floormodel. He has no experience with this model, but he assumed I'd be able to go into some kind of service menu to correct it.
    So, I think your best bet is to follow the instructions above, unless the set I was watching and yours are anomalies. Somehow I doubt it though.
    I am still very interested in buying this set, I have not seen a single TV in this price range that doesn't have some sort of geometry or other pictrue flaw. If this is the worst, I would be very happy.
    I hope some other owners of this set could chime in, perhaps this has been corrected in later versions of the TV. Now that I think of it, this would probably be better suited for the "Hardware" forum.
    /Mike
     

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