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DLP colour wheel mod

Discussion in 'Projectors, Screens & Video Processors' started by Jeff, Jan 10, 2002.

  1. Jeff

    Jeff
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    I though that I would open up a new thread about the DLP colour wheel mod that I have done. Up until quite recently most single chip DLP projectors used a 3 colour wheel with a clear segment. The function of the clear segment is purely to increase lumens making the projector brighter, but at the expense of colour fidelity and contrast. New DLP projectors designed for HC use don't have the clear section and so have better contrast, more vivid colours and blacker blacks. Business DLP projectors which tend to be much cheaper retain the clear section. The mod I did was to the clear section on a Plus U3-1080 (XGA DLP). To get to the wheel you need to remove the lamp and the top and front parts of the case, once you undo the screws, quite a lot a pressure is required in the right places to get the case open (I hate that bit). Both the top and front case parts are wired to pcbs on the projector so need to be detached, the process being similar to taking a laptop apart. With the top off and the lamp out you have fairly good access to the wheel. You can spin/dial the wheel (from the top) so that the small (about 15% of the wheel) clear section is visible though the hole where the lamp light passes through. I then used a permanent silver marker to cover the clear section and waited about an hour for the thing to dry out properly before putting it back together.

    So what are the results like, well I finished late last night so I haven't had the chance to properly assess, but right from the beginning I could see a clear improvement, at first the picture (windows desktop) actually seemed brighter which I thought was odd, I attribute this to greater contrast. I played a few scenes from the Fifth Element Superbit. Colours are more vivid, more depth, increase in contrast. Much more detail in blacks as evident in Bruces Tux. No perceived decrease in brightness accept the colours that are meant to be dark are darker.So all in all as mods go a clear winner. I will need to check that the permanent ink is holding up.

    Fingers crossed I shall be getting my Grayhawk screen today, I can't wait to see the picture on a properly masked screen.

    Jeff
     
  2. tiberious

    tiberious
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    Where did you buy your greyhawk ? (price and size ??)

    Thanks mate
     
  3. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Jeff: Excellent!!!!

    How hard does it look like to actually remove the whole wheel and change the filters in it?

    Gordon
     
  4. Jeff

    Jeff
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    The greyhawk I'm getting is 1600x900mm, email Gordon if you want to know prices.

    Jeff
     
  5. Jeff

    Jeff
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    It looks to me like you would have to take the whole thing apart to get the wheel out, not easy. You could probably change the filters on the wheel, the glass looks very high quality. I don't know how the DMD would react to major changes though, its probably incompatible with say a RGBRGB wheel. Come to think of it the existing wheel isn't RGB at all because I remember seeing yellow!

    Jeff
     
  6. skimber

    skimber
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    Do you know if this mod, something similar, or any performance increasing mods for that matter, are possible on the Philips UGO s-lite? this is a clone of the Plus isn't it? except that its only SVGA and not XGA

    cheers

    Simon
     
  7. Jeff

    Jeff
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    I'm sure that this mod would work on the x or s-lite, it doesn't look like Philips changed much.

    Jeff
     
  8. ReTrO

    ReTrO
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    Jeff: Should this mod not work on any single chip DLp with a white/clear section. Provided you can get the thing open?


    PS Hows the sub?
     
  9. Jeff

    Jeff
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    Yes, I would have thought so. I guess it depends how easy it is to get to the wheel. If I had to take the wheel out I wouldn't have done the mod.

    Subs doing nicely, the best compliment I can give it is that I don't hear it. :)

    Jeff
     
  10. ReTrO

    ReTrO
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    Jef: Does this affect the rainbow affect at all? It would be nice it it removed it a bit?
     
  11. Jeff

    Jeff
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    I'm not sure, but I must be doing something right because I'm seeing them less and less.
     
  12. skimber

    skimber
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    I might just pluck up the courage to give this a try :)

    is a silver marker the best thing to use? just the kind from most stationary shops or something special?

    Cheers

    Simon
     
  13. Roland @ B4

    Roland @ B4
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    I'm all up for this sort of mod and I hope it improves the image but I'm sure your warentee went out the window.

    Becasue the white (brightness) enhancing strip is no longer being used you should find the rainbow effect reduced. howver the processor will still be addressing and moving the chip to show this area so more colour artifacts may show.

    Just a thought on these pens. They hold the silver pigment in suspension as tiny particles and they are then effectivly stuck using the solvent/glue they contain. My wife uses these a lot in card making and other hobies and I have noticed that the silver rubs off easily. with the speed that the whell spins at is there not a danger of the dust getting into the rest of the optical block?
     
  14. Jeff

    Jeff
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    The pen I used is a Pilot Silver super color permanent type ink. I bought it from Staples. Think of this mod like overclocking for projectors, there are no guarantees (literaly) and it could all go terribly wrong. If all goes to plan you get 15-20% extra for nothing. Anyone thinking of going ahead should also read the threads on AVS, there are some far more detailed "how to's" there.


    Jeff
     
  15. Jeff

    Jeff
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    I received a couple of emails asking about my colour wheel mod. The person turned out to be someone from the http://www.heimkino-review.de website. He has now performed the mod and written an article about it. The text is in German but the pics are nice and show what is involved.

    Jeff
     
  16. GaryG

    GaryG
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    Jeff

    Have you tried one of the Tiffen or Hoya colour correction filters that the AVS guys are experimenting with?

    Trying to decide whether it's worth it. I would have thought that the correction could be obtained through the HTPC. The reduced black level is good but isn't that a trade-off with the reduced light output though the filter?

    Would appreciate your thoughts, the AVS guys seem to be getting very enthusiastic over this and may have lost their objectivity.
     
  17. Jeff

    Jeff
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    I'm using a Rodenstock FLD right now, I'm not 100% sure yet. Some pros and cons. Colours are definately better, brightness is decreased about 25%, contrast is down a bit I think. Sharpness is fine (this is a glass filter) I have another filter on order which has a lower filter factor, I'll let you know how it goes. I think that the best bet would be a very mild magenta filter, as it is a minor correction that we are looking for. Something that takes away the slightly green tint and corrects the reds so that they are fuller red rather than orange.

    Jeff
     
  18. skimber

    skimber
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  19. gizlaroc

    gizlaroc
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    I did this mod on my plus UP880 and it is well worth the effort.
    I thought i would loose a lot of light output but i cant really tell much difference, however the difference in black levels is quite a jump.
    I have taken a few pics of the Plus images and put them on my ftp, if anyone is interested.
    they are a bit blurry and i havent run Avia yet since the mod , but it gives an idea of black levels.
    I also cropped some of the pics and compressed them to jpg but that was all.
    these wre taken on a 6ft 16:9 screen made from blackout fabric.
    I will take some more on my 1.5 gain screen soon to compare.

    THE PICS

    There in the Projector folder, the other pics on there are of my car Im selling so excuse them.
     
  20. skimber

    skimber
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    Has anyone done any "Before & After" pictures of the same scenes?
     
  21. gizlaroc

    gizlaroc
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    I wish i had done a before/after set of pics, but to be honest i didn't think there would be any, or harldy any difference.How wrong i was.

    ah well maybe some one else will.

    I dont think the mod makes any difference to rainbow, maybe a little, but then i very rarely saw it before, well not on this projector, the only time i have seen it to the extent i couldnt live with it, was on the sim200 not the DM version mind you, havent seen that.
     
  22. Jeff

    Jeff
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    Bad news, the colour mod is a dud or it is on the Plus U3-1080 anyway. At some point after I performed the mod I noticed bad solarisation and that to combat it I was having to adjust contrast downwards on the Plus by 50 points and the Radeon by 10. When I first noticed this I thought it was my new Radeon 8500 and crappy drivers doing this. So I tried my old Radeon card again, but same problem. Yesterday I said enough is enough and decided to reverse my wheel mod just in case. I used white spirit and cotton buds, boy I needn't had worried about the permanent nature of the silver pen. It took me ages to get the stuff off, even then I didn't manage to get it all off. I switched the thing on and yes the blacks looked a bit grey and the colours muted, but then I readjusted the projector and Radeon card settings, nice bright image, plenty of contrast, no solarisation. I'm curious to know why the wheel mod didn't work for me, in the meantime you have been warned.

    Beware of the colour wheel mod!
     
  23. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Interesting...solarisation and crushed blacks ar eproblems I associate with HTPC set up.


    Keep pushin the envelope jeff...

    Gordon
     
  24. Paul D

    Paul D
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    On my old SonyVW10HT LCD, i found if i set the contast level too high. It caused me to notice "solarisation" much more, either from HTPC or direct from the DVD player.

    I think most digital projectors will suffer this to some extent.
    I wonder after you did the mod, in yor quest for better contrast pushed the level too high?. Ie trying to compensate for the slight loss of brightness etc. Maybe upping the brightness and retarding the contrast may have helped, sacrificing some of your new found contrast. :(

    Also i wonder what info you are losing when you blank the clear segment. Can you switch it off in the software etc?, othwise you are losing 1/4 of the info. This alone may cause the "solarisation".

    Then again what do i know!:D
    I just like having a stab at problems (when there somebody elses!)

    ;)
     
  25. Jeff

    Jeff
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    Since the LT150 crowd aren't having such problems I'm guessing that not being able to switch off the clear section in the setting is the cause. Never mind, it was worth a go and no damage done. I might try something else like tint it red.
     
  26. ReTrO

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    Is there a user/service menu that allows you to turn off the clear section on the 150 then?

    Sounds a good idea. Would you still needto black/silver out the clear section as well?
     
  27. Jeff

    Jeff
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    Yes a few DLPs have an option to disable the colour section, it sort of works, but unlike the physical mod it decreases CR. Undetered by my previous failed attemp I have done a different mod which I like so far. This time I have coloured the clear section with a pink highlighter pen. Probably not a huge difference but I do think that skin tones are more natural and it should have taken black levels down a notch. So far no side effects that I can see.

    Jeff
     
  28. ReTrO

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    Is it not possible to totally physcially remove the clear section and replcae it with a black bit? Or would it end up getting damaged beyond worth in the process, like the wheel falling apart?

    Cheers Jeff.
     
  29. Jeff

    Jeff
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    Possibly but the good thing about the mods for far is that they are totally reversable and don't require the removal of any major parts. I'm not sure that I'm brave enough to actually remove the wheel.
     
  30. Roland @ B4

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    It's a real shame to learn that this didn't live up to its expectations.

    What might be worth a try is a neutal density filter in the clear section which would leave some light coming through but not destroy the black level as much. or as you have already tried giving it a red/magenta hue.

    The other one I had heard off was to cover part of the clear section with black tape to allow just a couple of slits to be exposed so you got a sort of double flash.
     

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