Toshiba convergence drift after 16:9 squeeze

Discussion in 'Archived Threads 2001-2004' started by Jon Landrum, Apr 19, 2002.

  1. Jon Landrum

    Jon Landrum Auditioning

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    I have a Toshiba TN55X81 (4:3) which doesn’t have a factory 16:9 squeeze. Since this TV automatically stretches (vertically) any 1080i signal, I opted to perform the manual squeeze through the service menu. Though I was pretty successful (only slight geometry “issues” in the corners of the screen), I’m noticing a dramatic blue “convergence drift”. Has anyone done this procedure on the Toshiba TN series? Has anyone noticed the same problem?
     
  2. JohnnyG

    JohnnyG Screenwriter

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    I've done it on a few sets, but haven't had a problem like this. I really don't know what to tell you. Perhaps you're near the limits of the digital convergence system? This depends on things like the current values of the 9-point 'crosshairs', WID, HIT, PARA, ect. All these are additive.
     
  3. Gregg Loewen

    Gregg Loewen Video Standards Instructor, THX Ltd.
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    Gregg Loewen
    just what ever you do, DONT use the VPOS to try to center your image [​IMG]
    (I learned the hard way)
     
  4. Bill Slack

    Bill Slack Supporting Actor

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    Does VPOS move the raster, as opposed to VLIN, which moves the picture, electronically, within the raster?
    I've caused all sorts of havoc on my set screwing around with geometry issues on the HD input. It was just laughably bad out of the box. It seems to be somewhat respectable now, and I've learned a bit. [​IMG]
     
  5. JohnnyG

    JohnnyG Screenwriter

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    VPOS moves the image up and down (the convergence grid will not move). VLIN is vertical linearity. It adjusts...well...the vertical linearity(!) - making the picture more 'squished' at the top and expanded at the bottom, or vice versa.

    The X81 models have some sort of bug in the VPOS parameter and if you change it to move the image lower, all manner of crazy things can happen which basically requires an EPROM replacement to correct.
     

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