Toshiba owners, have you experienced this??

Discussion in 'Archived Threads 2001-2004' started by Steve Winkler, Jan 18, 2002.

  1. Steve Winkler

    Steve Winkler Stunt Coordinator

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    Recently, I have been testing out Progressive Scan dvd players on my TW56x81 rptv. In a dark scene on a 1.78:1 or 1.85:1 movie, and the top black bar on a 2.35:1 movie, on the top of my screen there are small areas of faint white light.
    It looks almost as if someone were behind the screen with a little flashlight in several spots. This only happens in progressive mode, when I switch to interlaced, it dissapears. I have both the Toshiba 3750 and Panasonic Rp-56 and it happens with each player. Is this ghosting or something else?? I am boggled and worried about this new problem with my set. Any suggestions??
    Thank you,
    Steve
     
  2. WilliamB

    WilliamB Stunt Coordinator

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    Hello Steve! I have a 56x81 and a Panny RP56. the RP56 has only been online for a week and only a handful of dvd's played (all anamorphic) but no trace of what you mention
     
  3. JohnnyG

    JohnnyG Screenwriter

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    Steve, what you're probably seeing is internal cabinet reflections. Some folks line the interior of the cabinet with material (Duvetyne) to absord the stray light.
     
  4. Steve Winkler

    Steve Winkler Stunt Coordinator

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    Thanks for the replys.
    JonnyG, always enjoy your posts over at KuSat. I considered that it might be interior cabinent reflections but they aren't there on any other input, dth sat, vcr, HD, or even dvd if it's interlaced. They only appear with a progressive scan signal even when there is no image on the screen. It is really distracting when watching a dark scene in a movie.[​IMG] I purchased an extended warranty with the TV, so maybe it's time for a service call huh?
    Any more thoughts as to what could cause this? I'm tempted to remove my screen and see if there is something turning on when a progressive signal is detected and causing the light.
    Cheers,
    Steve
     
  5. Allan Jayne

    Allan Jayne Cinematographer

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    Probable causes:
    1. The electron beam comes back on before all of the lines 481-525 have gone by and the electron beam is at the top left ready for the next frame. If the electron beam is on during these scan lines, garbage appears on the screen. To fix this you need to adjust the duty cycle of the beam blanking that spans the vertical blanking interval (may be labeled electronic matting in the service menu). Alternative, ncreasing the overscan may push these white flashes further away from the top border of the screen to hide them better.
    2. The DVD player might be putting the video on scan lines 2 - 481 instead of 1 - 480, leaving garbage on scan line 1. You can also use electronic matting or more overscan to hide this.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  6. Clinton McClure

    Clinton McClure Casual Enthusiast

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    Steve, I see the same thing on my Toshiba 40x81. Don't know what causes it. I adjusted the overscan up some, but a little light is still there.
     
  7. Steve Winkler

    Steve Winkler Stunt Coordinator

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    Thanks for the suggestions guys. I am still investigating.
    Steve
     
  8. StephenMSmith

    StephenMSmith Stunt Coordinator

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    Hey Steve. I know what your talking about.

    If you decrease the HIT of your picture so that the whole raster area is visible on screen, you will see that there are actually 2-3 short white lines (which are actually moving back and forth a little) on the screen just *above* the actual picture area. These odd lines were present w/both the 480p output of my Toshiba SD-9100 and my current Panasonic RP-91, but *not* 480p output from my computer. They are always present on the 480p output of my DVD players and are unaffected by actual picture content. I've always assumed these little lines were a result of macrovision, but I could be wrong (any thoughts on that, Allan?)

    Luckily, the solution is simple -- just adjust the top blanking of your set by lowering the BLKH parameter in the service menu down a few steps using the following procedure:

    1) set TV to Full mode

    2) display a full-screen solid background pattern like one of AVIA's white fields

    3) enter service menu and scroll to BLKH parameter

    4) lower BLKH (the default value is 11h) as much as you can w/o actually blanking out any of the visible picture on the screen (for me, this value was 0Eh, but it may be a notch or two higher or lower for you depending on set's geometry)

    This will blank out the raster located above the visible picture area, effectively covering up those dashes which are the source of the light that's bleeding onto the screen. This has the added benefit of reducing unnecessary light scatter within the lightbox as well. You might be tempted to adjust BLKL similarly, but be careful not to exceed 0Fh w/BLKL on the TWxxX81 because that will activate some type of auto-brightness limiter logic.

    There is also an issue that can occur w/the left and right raster sides. This is resolved by decreasing WID until you can see the both sides of the raster and then finding the HPOS sweetspot that minimizes the any glowing left or right raster edge. Then you leave HPOS alone and recenter the picture using the centering magnets.

    Steve
     
  9. Steve Winkler

    Steve Winkler Stunt Coordinator

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    Wow. Thank you Stephen. I will give the BLKH adjustment a whirl and see what happens. So far, I haven't noticed the left & right raster, and I hope I don't have that problem.
    Cheers,
    Steve
     
  10. StephenMSmith

    StephenMSmith Stunt Coordinator

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    Glad I could help out. I noticed this a long time ago and always found it odd that nobody else ever mentioned it. Your the first.

    I'd still like to know the true origin of these lines. Is it macrovision or something else?

    Steve
     
  11. Steve Winkler

    Steve Winkler Stunt Coordinator

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    Problem Solved!! I went into service mode and adjusted the BLKH parameter down just 2 clicks and the lights were gone. Thank you, thank you, thank you Stephen.
    This was quite an annoying glitch. You try to make your viewing area as dark as possible and then you get lights coming from the tv itself! Sheesh. Well, no more concerns about that. Have you ever posted this "fix" over at Keohi's site, because it sure is a good fix and easy too.
    Thanks so much,
    Steve
     
  12. Allan Jayne

    Allan Jayne Cinematographer

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    On NTSC broadcasts, closed caption text is encoded on one of the scan lines above the picture, I forget which one. If the TV's electron beam came on too soon for the start of the video field (adjusted with the BLKH or similar electronic matting parameter described above) and there wasn't enough overscan, you would see that scan line flashing at the top of the picture. If there was enough overscan and the electron beam drew that line on a part of the picture tube glass where there was no phosphor, you would not see extraneous light.
     

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