Can you replace burnt screens?

Discussion in 'Displays' started by Doug Z, Sep 26, 2004.

  1. Doug Z

    Doug Z Stunt Coordinator

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    With regard to the RP CRT's, if you get burn-in can you replace the screen? I understand the standard TV's are just one big tube with a screen but where does the burn-in occur on the rear projection's? I realize they use multiple guns to transform the image on to the screen but is it coming from the guns or the display screen itself?
     
  2. jeff peterson

    jeff peterson Supporting Actor

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    Unfortunately, the burn in is in the guns themselves.
     
  3. Leo Kerr

    Leo Kerr Screenwriter

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    With front projecting CRTs, yes, well, at least, in the past, you could replace the individual tubes. Theoretically, the same can be done in a CRT RPTV, since they're essentially a CRT FPTV in a big box with a screen and a honkin' big mirror.

    Speaking of which, does anyone know a good source of tubes for a Sony VPH-1001Q FPTV? Some of ours at work could use a new set... (something about running the same program for 12k hours...)

    Leo Kerr
     
  4. Doug Z

    Doug Z Stunt Coordinator

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    What has me confusd is all the old TV's and even the newer one's including computer monitors are all CRT's and have not a trace of burn in, why so with all the new technology are the rear-projection tv's establishing burn in at an early rate?
     
  5. ChrisWiggles

    ChrisWiggles Producer

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    Doug: projection CRTs are not "new" technology. Burn in on direct view CRTs, such as computer monitors, direct view TVs, etc always existed and still exists. I see it everytime I go to the bowling alley, or my local bank, where the same stuff is displayed every day. Or an arcade.

    Direct views drive their phosphors much easier than projection TVs, which have to illuminate a large space with a very very small CRT tube, and so it drives the phosphors much harder in comparison. Thus, projection sets are more prone to burn in, faster than direct views. but direct views are still prone to wear, as is ANY technology that uses emissive phosphors to create the picture (such as plasma TVs).

    You should read through the entire CRT master burn-in thread, which you did post in.

    Leo, you have a pm regarding tubes for the sony.
     
  6. Doug Z

    Doug Z Stunt Coordinator

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    I read through almost all of it until my vision started to blur[​IMG] That does make sense on the higher effort by the guns, it's just a shame the RP's do it at such an early age if you watch alot of 4:3. I was interested in the sony LCD's until the framerate issue had me scratching my head, and the PQ of the RP CRT's IMO beats the DLP's also, especially the price. While on the topic of framerate, where is this more a problem, on fast moving objects all the time with any resolution or with just the analog broadcasts? I really like the sony LCD's but after watching a football game at a friends, he was using comcast NON-HD signal and the picture had those little flies following the players, even at the 4:3 setting. I did not see it with sat or a good DVD but it has me second guessing the LCD's.
     
  7. Allan Jayne

    Allan Jayne Cinematographer

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    If you turn the contrast way down (to say 1/3 for TV/DVD or 1/4 for video games) the RPTV won't do it (burn in; uneven screen wear) at such an early age even with lots of 4:3 viewing on a 16:9 screen. The light level in your viewing room may make this precaution impractical.

    All those little flies (comet trails) following the players, or following a baseball in the air, or lighted objects panned by the cameras, are more noticeable on LCD because the liquid crystals have a delay in changing from light to dark etc. Also some CRT phosphors have a longer fade time than others (make and model) so comet trails may be noticeable on some CRT sets also.

    Comet trails can also occur in the video camera because of the nature of the pickup element inside (also a make and model issue), so a particular show may have them no matter what TV you watch the show on.

    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  8. Seth Paxton

    Seth Paxton Lead Actor

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    You could replace a single color CRT tube but I would expect poor results from having differently aged CRTs paired together. Without the experience of such repairs myself I can't imagine that a repair tech's advice wouldn't be to replace all 3 tubes together, and by that point it starts to look better to just buy a new set and get all new parts (and features).

    I don't know what the costs of these smaller CRT tubes are running at, but I've never known them to be cheap.


    Also, while we are on the subject, keep in mind that there are many methods for rear (and front) projection, and 3 color CRT tubes is just one of them. You can buy DLP or LCOS driven rear projection that does not feature burn-in as an issue. Those techs have their own issues of course, but the key point is that it is not the screen itself that is being burnt but the phosphors or even the shadow mask for the phosphors on the tube's face in the case of 3 color direct view CRTs.

    DLP mirrors don't burn, just like CRTs don't have a color wheel that could break or light bulbs to replace (other than the CRT tube itself).
     
  9. ChrisWiggles

    ChrisWiggles Producer

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    If only one tube is damaged or worn, then certainly you can replace that one. The tech doing it will set things up again so that grayscale is correct, etc. The only situation where you'd need to replace all three, is if all three were not in good condition. Usually G and B wear fairly fast, while R will last the longest. With normal wear and responsible use, only G and B tubes are ones that need replacing in many CRT sets. Also keep in mind that phosphor wear may not be the only wear that occurs, and depending on the tube type, set, there may be other problems occuring, like loss of beam focus with age, especially with ES focus sets.
     

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