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Guy, can you help with the Avia adjustment

Discussion in 'Archived Threads 2001-2004' started by Jeff D, Apr 25, 2002.

  1. Message #1 of 6 Apr 25, 2002
    Jeff D

    Jeff D Supporting Actor

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    I've got a Tosh tw56x81 and I had been throught the avia calibaration stuff many times. But lately I've notice a slight burn in where the 4:3 letterboxing happens.

    I just went to the avia disc to try and figure out what may have gone wrong.

    When I was testing the white balance (contrast) I have a tough time on the Tosh because the menus for the ajustments can't be removed from the display and the display covers the grey steps at the top half of the image.

    But, on my disply I NEVER see any blooming. White on the bottom half of the screen gets brighter and darker as I adjust up and down. The power supply appears to be pretty good to, there is no bending of the lines on the sides.

    So, how do you make these adjustments correctly in this type of an envrionment? Are there any helpful hints you may have?

    Also I'm a bit pissed at Tosh for the "reset feature" on the remote which when pressed bumps your contrast to 100 and all other values to 50. Contrast at 100, that's a sure fire way to kill a display.
     
  2. Message #2 of 6 Apr 25, 2002
    Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    The AVIA pluge and needle pulse patterns tell you where not to set your contrast.

    They do not tell you where to set your contrast.

    You have probably effectly been driving your TV at a functional equivalent of 5999 rpm ... just short of the 6000 rpm red line. Well, 5999 isn't good for your TV either.

    It typically needs to be at about the 30 to 40% make and never higher.

    Regards
     
  3. Message #3 of 6 Apr 26, 2002
    Jeff D

    Jeff D Supporting Actor

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    Sounds like you are arguing my point. =)

    As you saw before I have now got some sort of sligth burn in (looks like green crt, red and blue it's not really visible)

    So I took out the trusty Avia disc to see where I went wrong. I used the needle pulse pattern and tried to see what was wrong. I could set the level to 100 without blooming (now I know 100 isn't a good leve to set it at) I would bring it all the way down to maybe 30's before the white started going to grey.

    My question was this. If that test doesn't help you figure out how to correctly adjust contrast (white level) what do you do instead?

    I'm just trying to get this fixed before I cause any more damage.

    Thanks!
     
  4. Message #4 of 6 Apr 26, 2002
    RyanDinan

    RyanDinan Stunt Coordinator

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    Michael,

    If we have instrumentation (such as a colorimeter), is there a specific "safe" ftL number that we should stick to? 10-13ftL is what I've been seeing as "safe"...

    Also, I remember you saying that color analyzers and colorimeters tend to only show you 1/3 the actual ftL number - Is this correct? If so, I would assume we would consider a reading of 3.33ftL to be our target?

    Thanks!

    -Ryan Dinan
     
  5. Message #5 of 6 Apr 27, 2002
    Guy Kuo

    Guy Kuo Supporting Actor

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    As Michael and the AVIA disc's instructions indicate, you don't aim to stay at the point of blooming. That's just for looking for "red lining" The instructions on the disc go on to how you end up at the final for contrast.....

    -----

    Narrator:Now that you know the upper limits for white level on your display, it's time to set white level for viewing. Be sure room lighting is at normal viewing conditions then display the Needle Pulses and Steps pattern. Begin with white level at a low enough setting that the lower half of the pattern appears gray. Gradually increase white level to the point at which the lower half of the pattern ceases to be a shade of gray and appears white. Each log step rectangle should also appear twice as bright as the one below. As you adjust white level, remember to always stay below the points of blooming or white thresholding that you have determined earlier.

    This setting is probably lower than what you are used to. Increasing white level beyond this point sacrifices image accuracy and may even reduce the life of your display. If it seems too dim, consider futher reducing room lighting.

    ------

    In other words, it says to turn it down to the lowest contrast setting which makes white look white.
     
  6. Message #6 of 6 Apr 27, 2002
    Michael TLV

    Michael TLV THX Video Instructor/Calibrator

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    Greetings

    With instrumentation, we tend to shoot for a light output from the 100 ire window of 20 ft-l.

    And we usually end up somewhere from 15 to 20 range.

    The colour analyzers tend to understate the light output from the RPTV's because of the screen. The rule of thumb is to take the reading and X3. So 6.8 ft-l tends to be around 20 ft-l.

    Regards
     
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