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I got rid of the vertical banding problem! Here's how...

Discussion in 'Projectors, Screens & Video Processors' started by tahustvedt, Apr 23, 2002.

  1. tahustvedt

    tahustvedt
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    YESSSSSSS!!!!

    I couldn't keep myself from trying the settings in the service-menu. My Hitachi CP-X275W (and many other LCD-projectors) has a lot of vertical banding on the green and blue panels. This was beginning to annoy me extremely, even more than the stuck blue pixel in the middle of the screen.

    [​IMG]
    The banding is visible here. The blue panel also has this banding.

    I heard about a Sony VPL-CS2-user who had adjusted the voltage to the panels in the service-menu and removed the banding on his projector. I also heard about a guy who adjusted some settings called "V.COM" in the service-menu of his Sanyo PLV-60 and also removed the banding.

    The service-menu of my projector also has a setting called "V.COM" with separate figures for each color. Choosing one of the colors, green for example, shows a screen where every other line is green on a black background. The green was flickering a lot and the blue and red were completely still. Increasing the value stopped the flickering and reducing the value made it worse. Someone stated that this setting is there for adjusting flicker, and that seems to be exactly what it does. :) But it also has a severe impact on the banding pattern that is a problem on this projector. The original values were R 157 G 164 B 171. I used the flight-scene in Jurassic Park III as a test screen because that's a scene where the banding has been very visible and annoying before. The scene was running in the background so any changes were visible as soon as I moved the cursor to the left in the service-menu.

    First I tried lowering the green value to 130. The banding in the sky was now much worse and I began to gain hope. :) Raising the green value to 190 improved the banding a lot, but it didn't remove it. Then I tried raising the blue to 190 as well and the banding was gone! :eek: My heart skipped a beat and I cracked a large grin!:D Success!

    Although I have experience with the service-menu of CRT-TVs I didn't really know what I was doing with all the strange values here, I was just satisfying my curiosity but I did discover something which might be very helpful. The question is, Is this safe or will it cause damage to my expensive toy? I changed the settings back to the default before I exit the service-menu because I'm still a bit scared to leave it like that for longer periods.




    Here's the procdure for entering the service-menu on the Hitachi CP-X275W (and probably almost all Hitachi-projectors):

    Warning:
    Always write down the original values before you try anything. Be aware that changing settings in the service-menu can really mess up the way the projector works and there is a good chance it might damage the projector too. Don't complain to me if you break anything! :) Service-menus are always scary and can be confusing. Don't blame me if you mess it up.

    1. Press "menu" once.
    2. Press "reset" once.
    3. Press "reset" again and hold for five seconds.




    Tor Arne


    Curiosity killed the cat! ;)
     
  2. Jonny1973

    Jonny1973
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    Anyone know how to get into the REAL service mode for the Panny PT-AE100?????

    I know about the "hold enter on OSD in the options menu" one but that doesn't let you change anything much.

    There must be another service mode.
     
  3. tahustvedt

    tahustvedt
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    Here are some examples of the difference. The pictures are taken at the exact same time in the movie as the DVD-player was paused all the time. They are actual screenshots of the banding.

    Before:
    [​IMG]

    After:
    [​IMG]

    Before:
    [​IMG]

    After:
    [​IMG]
     
  4. Kramer

    Kramer
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    I can't wait to be able to fix this on my AE-100.

    The vertical banding I have is exactly the same as that above, & is present on another AE-100 I've seen.

    Must have a play with my remote later, see if there's any more "easter eggs" on this PJ :D
     
  5. Anim

    Anim
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    Very Interesting. Thanks for posting your find Tor.

    I had V Banding on the second panny i got, if there is V banding on the third one then finding out how to adjust it would be very useful.

    Anim
     
  6. Guest

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    I sent my toshiba off to have this sorted out! It did come back much better. But looking at your pics I have to say I am very impressed.

    2 questions please:

    1 - does anyone know if there is access to a service menu on the toshiba MT1, and if so how?

    2 - you said about resetting the defaults before leaving the menu. Could adjusting some of the settings really damage the projector?


    Thanks
     
  7. tahustvedt

    tahustvedt
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    I have been assured by some people at AVSforum, who have the service-manual for a Hitachi-projector, that these settings are only visual, and win't do any damage. Setting it too high can cause flickering but I haven't seen any flickering. I think you have to go really high for it to start flickering.

    I don't believe it has anything to do with the voltage to the panels.

    The overall picture quality is much better now. The colours and contrast look like they improved too. I may have been lucky and hit a good white-balance point when making the adjustments. :)


    Tor Arne
     

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