does your RPTV hold black to the edge of your screen?

Discussion in 'Archived Threads 2001-2004' started by Rob Michaw, Nov 15, 2001.

  1. Rob Michaw

    Rob Michaw Stunt Coordinator

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    I have a Toshiba 42H81 (2 weeks now) and in some very dark scenes, I have noticed that along the edges of the screen, the blacks seem to get ever so slightly lighter.
    I though I may have some light coming from beyond the screen (in the overscan area), but now I am wondering if it is just the nature of the set to slightly get lighter at the edge (about 1/4" in width). I only notice it when a very dark color or black happens to run off the set on either side. A first it looked like it was only happening on the left-hand side, but now I am thinking that maybe it is equal on both sides.
    Thanks.
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    rob michaw
     
  2. Jeff D.

    Jeff D. Supporting Actor

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    Rob:
    I have seen this effect on mine, and other sets as well. Some thoughts...
    I think internal reflections are part of the problem. The image being projected from the CRTs is not perfectly sized to your screen - it is actually larger. At the edges of the screen frame, there are reflective materials - brackets etc. - which could reflect this "extra" light and thus diminsh the blacks at the edges.
    Installation of Duvetyne fabric, which aims to cancel such reflections (it is a blacker-than-black fabric that does not reflect light), is somewhat effective in alleviating this problem.
    I believe there used to be a way to control how far off the screen the projected image is - the controls were vertical and horizontal blanking, if I am recalling correctly. Of course, these were all service-level parameters. Unfortunately they do not exist anymore.
    I have not heard of any other methods of solving this problem.
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    Jeff
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  3. Rob Michaw

    Rob Michaw Stunt Coordinator

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    Hi Jeff -
    Thanks for the response. I have another question for you if you don't mind. I checked the overscan of my set, and noticed that I was at 5% on the top and bottom, but around 7-10% on the sides. I adjusted HIT and WID until I got to 5% all around (my convergence grid has now grown).
    Doing this, I should have the correct 16x9 proportions, right? My circle hatch pattern looks great, and my circle is a very round circle, so it looks good to me. The only thing is, when I look at my HIT & WID values now, my WID was reduced by 2 over my original values, and my HIT stayed exactly the same. Does that make sense? Have I been watching for two weeks with a slightly stretched image? Are things right now, or am I doing something wrong now?
    Thanks. Every time I think I have my last question, I come up with another one!
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  4. StephenMSmith

    StephenMSmith Stunt Coordinator

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    Try this:
    1) display AVIA's 100% black windowbox pattern
    2) crank up the user settings brightness to 100%
    3) select Full mode and reduce WID until you can see both left and right sides of the raster area (the raster area will be lit up due to 100% brightness)
    4) observe the left (or possibly right) edge of the raster area at both 100% brightness, as well as normal brightness in a darkened room.
    5) if you notice a bright band at either edge (mostly likely the left side), then that is your problem.
    It can be fixed by adjusting HPOS to the point where there is no bright line on either side. This will move your picture off center, so you use the CRT centering magnets to recenter the picture.
    Steve
     
  5. Jeff D.

    Jeff D. Supporting Actor

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    Correct. If your overscan is even on all sides, you should be ok. One note, however: don't use Video Essentials for overscan. The test pattern is incorrect. Use Avia for Overscan adjustment.
    Of course, an easy check is to measure your circle's height and width - should be equal. Don't worry too much about the values. These sets rarely come set correctly from the factory. It is very possible the image you have been watching is incorrectly proportioned. Usually, the error is slight and the casual viewer wouldn't notice. But for us more discerning folks...nothing but the best will do. [​IMG]
    ----
    Jeff
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    "They're coming to get you Barbara..."
     
  6. Rob Michaw

    Rob Michaw Stunt Coordinator

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    Steve -
    Sorry for the lack of understanding, but what is that in refernce to? Holding black to the edges of the screen? How do you use the CRT magnets to center the picture, by opening up the set?
    I am dwelling on this issue of a lighter edge on the screen because I have the ability to return the set and get another one (hopefully wihout that problem). My concern is that returning it and getting another one might not solve the problem (if it is inherent in all models), and I might get another set with different problems.
    If opening up he set or doing some tweak can solve this problem (if it exists on all Tosh 42H81s), I will tackle it. If this is unique to this set, then that makes me want to try another one.
    Also, on a disc like Close Encounters, when the menu at the beginning appears and the color bar lights up on the black background screen, I notice a half-moon of light around the color bar...like a halo. Is that also normal for the RPTV, or is that unique to this set?
    Thanks.
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    rob michaw
     
  7. Jeff D.

    Jeff D. Supporting Actor

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  8. Rob Michaw

    Rob Michaw Stunt Coordinator

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    Could this also possibly be a power problem in my basement? I noticed today that when flicking a lightswitch on or off on the same breaker as my home theater, the TV flickered. Would a power conditioner help the flicker, and could a power conditioner help the black to the edge of the screen?
    Maybe it doesn't have anything to do with the tv holding black, but I am looking for a problem that I can remedy instead of just chalking it up to the tv and living with it or giving it back and starting all over again.
    Thanks.
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    rob michaw
     
  9. Jeff D.

    Jeff D. Supporting Actor

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  10. Rob Michaw

    Rob Michaw Stunt Coordinator

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    Thanks for the help.
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    rob michaw
     
  11. Massimo N

    Massimo N Stunt Coordinator

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    This is probably caused by internal reflections, but not the cabinet, rather the screen assembly. On the new toshibas, the touch focus sensors (4) and the side black metal brackets are probably contributing to the problem.
    It's not bad on my set, so I haven't done anything yet. Possible solutions...
    -Remove touch focus sensors (do 56 pnt convergence instead).
    -line brackets with duvetyne
    -lens stripping.
     
  12. Jeff D.

    Jeff D. Supporting Actor

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    Massimo makes a good point. There is a lot of reflective stuff around the perimeter of the screens - excellent candidate for Duvetyne.
    ----
    Jeff
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    "They're coming to get you Barbara..."
     
  13. Rob Michaw

    Rob Michaw Stunt Coordinator

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    Do you know if all models exhibit the same intesity of this effect? I am now starting to believe/understand that this will most likely be present on any set I get, but since I can still return it for another one, I am just curious if some sets just have more reflections than other like models.
    My deadline for decision on keeping or trying again is tomorrow. If I try another one, I start everything from scratch and cross my fingers it is as good, if not better. If I keep it, I will think about a lens hood or Duvetyne, but the concept of opening up my set is a little on the scary side. Doesn't putting Duvetyne in your set void the manufacturer's warranty? Would the lens hood not void the warranty if you removed it before any service to the set was done?
    Thanks again...all the questions are staring to get embarrassing [​IMG].
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  14. Jeff D.

    Jeff D. Supporting Actor

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    Rob:
    Don't feel embarrassed...the only stupid questions are those that are not asked. [​IMG]
    The problem in general is simply one of the down-sides of a rear-projection unit. Every setup has compromises, this happens to be one of them. Fortunately the benefits of RPTVs far outweigh the negative points...IMHO, anyway.
    Now, having not seen your set specifically I cannot, with 100% confidence, say that there is nothing wrong with it and that you have received a faulty unit.
    Having said that, I feel reasonably confident that there is no problem. If possible, try getting to a store tomorrow and looking at some sets there. See if they exhibit the same problems. Try and look specifically for your model. You may find them improperly calibrated (not at Creative, of course [​IMG] ), but a quick adjustment of the picture controls will you put on an even playing field. If the sets there are wildly different than your's, then perhaps you do have a problem.
    All RPTVs will offer varying degrees of the common problems inherent in the design. Some handle internal reflections very well, others not so well. So many factors at work, some variation is expected.
    Re: warranty. Absolutely. Technically, once you open up that unit, the warranty is voided. Now, in most cases no one can tell if you've been inside. If you permanently install Duvetyne, there will be no hiding it. Some have installed using a removable medium, such as staples, to allow for a quick "out" if you need service. The lens hood is a removable piece, so that needn't be a problem.
    But yes, at the end of the day, any inside work will void a warranty.
    ----
    Jeff
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  15. Rob Michaw

    Rob Michaw Stunt Coordinator

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    I am pretty sure now that my problem is cause by internal reflections, but I am now wondering if reflections get worse after you do a 56-pt convergence and geometry adjustments?
    I never noticed the reflections till after I did the adjustmetns, but maybe I just didn't notice them before.
    Here is a mocked version of what I am talking about. This isn't a picture of my actual setup, but it is a varied version of a digital image I have snagged off the forum (Phil I. I think). This is somewhat of an exagerration for the purpose of displaying to members what I am experiencing, but this is very close to what it looks like...just less noticeable.
    image
    Thanks again [​IMG].
     
  16. Rob Michaw

    Rob Michaw Stunt Coordinator

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    OK...stop the presses! The bright edges look worse on cable TV than they do on DVD. My contrast setting is low...very low, but I personally think my cable reception looks much better since I reduced the contrast and upped the brightness (contrast 20, brightness 66).
    Screwing around with contrast and brightness settings, I lowered my contrast to 0 and upped my brightness all the way to 100. The cable image lacked all blacks, but was almost silky smooth. When I increased contrast and reduced brightness, my blacks started to come back, however the cable reception becomes noisier.
    When I had settings around 35 contrast and 50-55 brightness, the ringing of lighness around the edges of the set almost (not quite) disappear.
    Have I just had my settings too low on contrast and maybe too high on brightness? On DVD, my settings are slightly different (contrast 27 and brightness around 57). Setting contrast with Avia is a very difficult thing for me, as the blooming only moderately appears, and the lines on the side never seem to bow...even at high contrast levels. Should I try and boost contrast to 35ish and adjust brightness and other settings accordingly?
    Hmmm...maybe this has been my problem all along [​IMG]. When is brightness set too high if the lines on the sides of the Avia brighness adjustment pattern don't bend? Blooming looks like it occurs at anything over 20, but very minimally. How much is acceptable in real-world terms?
    Thanks again...and again...and again.
     
  17. Jeff D.

    Jeff D. Supporting Actor

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    Rob:
    Don't even try to adjust picture settings using cable and make any sort of judgment on picture quality. Beyond the fact that cable in and of itself is just a terrible source, each individual station will also vary significantly. Adjusting the controls to make one channel look good will prove fruitless when you change the station only to find that the next channel is even worse.
    Now, as for setting Contrast. Yes, it is extremely difficult - the hardest of all the controls. [​IMG] I find the easiest way is to get right up to the screen. Put your nose up to the screen (don't leave a smudge on the screen though! [​IMG] ). Bring up the Contrast adjustment pattern on Avia and watch the top white box in the gray steps. As you slowly turn Contrast up one notch at a time, there will be a point where the box stops getting brighter but actually increases in size. This is easy to see when you're up close. This is the point of blooming. Step away!
    The point of blooming is not the correct setting for Contrast. It is simply a warning point - you should definitely not be this far up on the Contrast control.
    The best method that works for me is to turn Contrast down to its minimum. Then slowly rock it back and forth between the minimum and the maximum (ie. point of blooming). Watching the white area on the bottom half of the screen, slowly you will notice that there is a certain point where it is distinctly white as opposed to gray. Once you find that point, that's your setting.
    Brightness setting has nothing to do with bending lines. Use the Brightness test pattern in Avia. In the left black area of the screen you will see two moving black bars (crank up brightness to see them). Simply turn Brightness down until the bar on the left disappears and the one on the right is barely visible.
    ----
    Jeff
     

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