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Screen Replacement on Toshiba TW56F80

Discussion in 'Archived Threads 2001-2004' started by Darren Hunt, Jun 17, 2001.

  1. Darren Hunt

    Darren Hunt Agent

    Jun 16, 2001
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    About 2 years ago I accidentally scratched the screen on my Toshiba 56" 16X9 RPTV. Knowing that I was going to be moving soon, I decided holding off on replacing it until after the move. Well, now I have my own house, 3/4 of the way done on my home theater, and a new screen in my TV.
    When I replaced it, I did some research and read a bit about a few people using a Da-Lite Diffusion Screen instead of the Toshiba factory part. I decided to go forward with this as everyone seemed quite happy about it. This is how I feel about the whole thing.
    The new screen has a slightly sharper picture and is definitely more bright. I recently had it ISF calibrated by Micheal (The Laser Video Experience), and through some hints from him I have improved the appearance substantially. Without the linticular lines of the Toshiba screen, the picture becomes brighter, and the viewing angle is essentially 180 degrees.
    My only problem with the whole thing is that I now have a very visible ghost image that roams around the bottom 1/4 of my screen during dark scenes that have bright objects located from 3/4 and up on the top of the screen. I have built myself a lens hood, lined the inside of the TV with Duvetyne and still, I have the ghost images. I was getting a bit frustrated with this, so I started looking further into it and this is what I have figured out. With the positioning of the mirror/CRT's/screen, I am having any bright object located near the top of the screen being reflected back to the top of the mirror, and reflected back down to the bottom of the screen. If the screen/mirror/crt's were in 90 degree positions, this would not happen, but since most of today's RPTV's have slim cases, the angles have to be changed to squeeze everything into the slimmer box. This allows a second reflection off the top of the screen to reach the bottom of the screen, making a ghost image. No matter how much Duvetyne you throw in, you would have to mask off the top 6 inches of your screen or mirror to be rid of the ghost, which also happens to mask off the top of your picture and cut peoples heads off (which is unacceptable of course).
    I have now masked off enough of the top of the mirror (without hindering the picture) and have reduced the ghosting to only the bottom 1/4 of the screen, but it is still there. There is nothing I can do to fix this short of cutting the TV apart and changing the angle of the CRT's to the mirror to the screen into a 90 degree angle. Right now, the CRT's are angled about 25 degrees from the vertical, hit the mirror (~30 degrees from the vertical) onto the vertical screen. If the CRT's could be pointed straight up, and the mirror positioned at 45 degrees, the problem would be eliminated.
    I figure the old Toshiba screen blocked enough of the light that the ghosting was there, but so faint it was undetectable. When I had the old screen, it was also in a room with quite a bit of light pollution, which probally hid the ghost as well. With the new screen, which allows more light through, the ghosting has become more prominent. With the diffusion screen, I can also say the picture's blacks are bit grayer, but not enough to bother me. Seeing as I have virtually complete control over the lighting of the room, it doesn't bother me much. If the scene is not during the night, and contains little darkness and lots of color/bright objects, the ghosting is not visible.
    So the end question is.... do I like the new screen or not? Over all I am happy with the viewing angle improvement and the brighter/sharper picture. I could do without the ghosting, which is only visible for about 5% of a show during dark scenes. The price of the screen was quite high (approximately 3 to 4 times the cost of the Toshiba part) which I think is the biggest determining factor. If I had to do it again, I would probably keep the scratch and save up for a front projection, giving me complete control over all my viewing factors.
  2. Michael TLV

    Michael TLV THX Video Instructor/Calibrator

    Mar 16, 2000
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    Calgary, Alberta
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    Michael Chen
    Greetings Darren
    Thanks for the update on your situation. I was wondering about how you might address the internal reflection issue even with Duvetyne and the lens hood. Now I know. [​IMG]
    Always a penalty of some sort with every upgrade ... grrr.
    Thanks again.
    Michael @ The Laser Video Experience

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