• home theater 28.08.2008

    If you have question about this project drop me a line : theone at bonmul.com

    Photos are at the bottom

    Update 1: Some answers to comments:

    About focus: It’s not out of focus. It’s as crisp as it was with the original small screen.

    About dust: The projector unit is in its own box, so dust does not go into the projector itself. If you see the photos, there is a plastic wall behind the screen and all the electronics are hidden behind and below. When you open the screen, all you see it projector lens, a concave shaped plastic walled enclosure and a mirror on the top side. I actually bought a transparent acrylic sheet and put it in the place of original screen, but it acted as a mirror and refracted the image,so I had discard it. There should be some coating available to negate the mirror effect, which means you can completely close the front with a transparent  plastic sheet.

    1. Big screen TVs shrink (by perception, of course)

    I bought Sony KDFE50A10 rear projection TV that has 50″ screen. After
    an year or so, I started to feel like the screen size is shrinking,
    really, ask any one who has a big screen TV. I wanted to buy a
    projector and have 100″ screen. But with more than $2500 already
    invested in the RPTV, the WAF (Wife Approval Factor) to upgrade is zero. So, I have been
    thinking to convert this RPTV into a rear projector, but I couldn’t
    find any help on the net.

    2. Proof of concept - Is it possible?

    Nervously, I opened up outer cover of RPTV with by unscrewing the 20
    plus screws. Then removed the screen. Placed the TV in front of the
    wall at 6 foot distance, viola!, the entire wall is filled with
    picture. Clear, bright and fully focused. Will it
    be good rear projector? To check out, I  bought a plastic shower curtain
    from Bed, Bath & Beyond, hung in front of the TV and, ta da…, huge,
    bright, clear picture and with crisp focus. Cool!

    3. But, the setup should be house worthy?

    I needed to figure out how to make it look good, so it won’t look
    cheap or ugly. I came up with a plan. a) Build a wooden frame 8′ width by
    8′ height b) Hang a screen with metal frame on this wooden frame. c)
    Cover the sides, top and bottom with velvet fabric. 4) Place TV with
    screen opened behind screen at appropriate height and distance.

    My home theater room is in basement, about 17′ x 20′ size. I decided
    to place it in corner so it won’t feel like it occupied half the room.

    4. Buying the screen

    Searched for a rear projection screen on the net, but most of them are
    $3000 plus, except one from http://www.htdepot.com/, for $350 with
    aluminum frame and velvet border. I could have also built a wooden
    frame and got the fabric only and stapled to the frame., which wood have been dead cheap. But that
    thought came later only after I built a wooden frame to hang the
    screen. If I do it again, I would do that and save money. You can find rear projection fabric from eBay or HTdepot.com. The screen came in great package and after assembly, it looked awe
    some. The screen size was 100 inches (viewable 100″, with borders 105″).

    5. Building the frame

    Bought four 2×2 wooden pieces of 96″ length. Got metal framing clips -
    the L shaped metal pieces that join wood perpendicularly from home depot. Made a
    rectangular wooden frame out of these. Stood up the frame about 6 foot
    from the corner of the wall. Also bought some screw hooks (It is screw with circular head, to hang pictures) Screwed some hooks into the top wood and tied the frame to the ceiling (I have a drop ceiling) with a thin metal wire at four places, so the wood frame won’t fall. Don’t tie it permanently yet, it
    may need to move to adjust the projection.

    6. Hanging the screen on the wooden frame.

    The screen’s aluminum frame had hooks to hang the screen. So hung the
    screen on the wooden frame leaving equal gap below and above the
    screen.

    7. Positioning the RPTV

    This is the trickiest part of all. There is no stand available that
    will let you adjust height to exact tenth of an inch. So I built my
    own adjustable stand. I bought two saw stands (also called work horses)
    (http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?storeId=10051&langId=-1&catalogId=10053&productId=100026516&N=10000003+10401001)
    with adjustable height, cut a plywood in the shape of TV’ base with
    extra 2 inch border around. Placed the ply wood pieces on the two
    stands and my adjustable TV stand was ready! I placed rear projection TV on the stand and made height and
    distance adjustments until the image from the TV fit exactly on the
    screen.

    8. Covering the sides, top and bottom.

    From Linen n Things shop, I bought four velvet curtains. Two in red

    for sides, two in black/ dark blue for the top and bottom. They were of 96″ length, so fit perfectly on top and bottom and sides as well. For hanging side curtains, I used circular hooks and metal chain (for rugged effect, it looks cool actually). I screwed one hook on the side of the frame at the top, and another hook on the wall at same height. Then inserted the chain through the curtains sleeve and tied to the hooks (I actually opened link, inserted in the hook and closed the link again). For top and bottom covering I just used nails to keep it in place.

    9. Photo Gallery

    Explanation of the photo is below each image.

    Removed screen from RPTV

    Removed screen from RPTV

    Projector lens of RPTV relflected in the mirror

    Projector lens of RPTV reflected in the mirror

    Frame corners showing metal plates the hold frame together, used screws instead of nails for easy dismatle

    Frame corners showing metal plates the hold frame together, used screws instead of nails for easy dismantle

    Two height adjustable saw stans raised to correct height and plywood peice is placed on top

    Two height adjustable saw stands raised to correct height and plywood peice is placed on top

    Rear projection screen is assemble and ready for mout. Alluminum frame covered in velvet

    Rear projection screen is assemble and ready for mount. Aluminum frame covered in velvet

    Side curtain in red is hung off a chain, top curtain is nailed to the frame

    Side curtain in red is hung off a chain, top curtain is nailed to the frame

    Kepping all in perspective - the screen, frame and RPTV

    Keeping all in perspective - the screen, frame and RPTV

    IR transmiters for components hidden in closet and Vista MCE

    IR transmitters for components hidden in closet and Vista MCE

    Rear projection in action

    Rear projection in action

    Complete setup

    Complete setup

    Screen shown in fully lighted room

    Screen shown in fully lighted room

    Surnrise earth on Discovery HD 1080i picture is stunning

    Surnrise earth on Discovery HD 1080i picture is stunning

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    Posted by BonMul @ 7:01 am

    Tags: , , , , ,

  • 36 Responses

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    • Hack your rear projection tv to be bigger - Hack a Day Says:

      [...] but can’t afford it?  If you Have a rear projection TV, why not just get a bigger screen?  That’s exactly what was done here. They dismantled the old TV, mounted it and enclosed it theater style, with curtains.  They then [...]

    • Make your rear projection tv bigger - Tweak3D.Net Says:

      [...] Convert your RPTV into Gigantic Home Theater | BonMul.com Pretty cool hack. [...]

    • Nick Says:

      How do you keep dust off the lens and mirror???

    • The 100-inch Rear Projection Television Upgrade [DIY] Says:

      [...] a c­heap pr­ojec­t­or­ or­ som­et­hi­n­g… [B­on­­Mul vi­a [...]

    • Device Killer Says:

      Which reverse projection screen did you buy? Do you mind publishing the URL? The ones I see on HTdepot.com are all front projection screens.

    • antuan goodwin Says:

      Isn’t the lens of the RPTV a fixed focal length? With this in mind, wouldn’t placing the screen what looks like 2 feet in front of the original frame place the image slightly out of focus? Is this compromise in clarity noticeable and if so, is it worth the extra screen size?

    • The 100-inch Rear Projection Television Upgrade [DIY] | CHARGED's 24/7 News Aggregator Says:

      [...] it now runs at lights-off brightness levels. You know, like a cheap projector or something… [BonMul via [...]

    • questionista Says:

      could you post some video of the setup?

    • CrunchGear » Archive » DIY: Convert your RPTV into a gigantic & tacky home theater Says:

      [...] it’s your RPTV and livingroom. Have at it via [...]

    • DIY: Convert your RPTV into a gigantic & tacky home theater | CHARGED's 24/7 News Aggregator Says:

      [...] it’s your RPTV and livingroom. Have at it via [...]

    • toltecnightmare Says:

      Why not build the wall out around the screen, or increase the size of the cabinet all together and paint the inside flat black? That would retain more light for you viewing pleasure….

    • Carlos Martins Says:

      I have one of those Sony RPTV - nice way to upgrade. :)
      Thanks for sharing your project with us.

      By the way, have you ever had the bulb replaced? Any suggestions on where to get it for cheap? I guess mine still has another year to go, but better start looking.

    • Joejubee Says:

      Can you comment on the focus-factor? I’d anticipate that the focus would get all out of whack, and be too off to be corrected using the tv’s focus controls. Good hack though!

    • BonMul Says:

      Focus is perfect. When I opened up and put the projection on the wall, I was surprised. The focus is crisp, as it was with the small screen.

    • HDTV Hack - How to Convert your RPTV/DLPTV into a 100-inch TV! | zedomax.com - The DIY, HOWTO, Hacks, Gadgets, and Tech Blog! Says:

      [...] hackaday, DIY PAGE A+Featured Hacks, cinema screen, Consumer, Cool, dlptv, DoItYourself!, DoItYourself!, Educational, [...]

    • DIY 100″ TV - Deadly Computer Blog Says:

      [...] Regardless, good job.  You can read about the steps here. [...]

    • Daily Digest for 2008-09-30 | Pedro Trindade Says:

      [...] Convert your RPTV into Gigantic Home Theater | BonMul.com This entry was written by trindade, posted on September 30, 2008 at 11:59 pm, filed under Lifestream. Bookmark the permalink. Follow any comments here with the RSS feed for this post. Post a comment or leave a trackback: Trackback URL. « Daily Digest for 2008-09-29 [...]

    • Daily Digest for 2008-10-01 | Pedro Trindade Says:

      [...] Convert your RPTV into Gigantic Home Theater | BonMul.com [...]

    • Zamiana 50 cali na 100 domowymi sposobami - HDTVMania.pl - blog o telewizji nowej generacji Says:

      [...] Szybki (i niestety troch? ma?o szczegó?owy) poradnik jak to zrobi? znajdziecie na tej stronie. [...]

    • Nico Says:

      Bravo. As someone in a household with high WAF measurements, I salute you sir!

      I actually have a projector but it’s been an uphill battle to get a permanent home for it. Instead I have to set it up every time we want to have a bigger picture than the laptop screen - drag the wires, focus, etc. Reminds me of the ritual we went through when I was a kid and we watched Super-8 movies!

    • Så fixar du större bildyta | Hembiokoll.se Says:

      [...] Så om du inte tycker att du har råd att köpa en ny projektor eller teve, men ändå vill ha större bild från din bakprojektions-tv, så hittar du en lättläst och utförlig guide här. [...]

    • Jack Says:

      Still curious about how the focus would not be off. Any experts care to reply?

    • chuck Says:

      I’m no expert but I think I know why the focus doesn’t change.

      The image comes out of the lens and is reflected off of the mirror which then is displayed on the screen. The image only has to be in focus where it hits the mirror for the picture to be clear on the screen. Really the screen, or whatever you are projecting it on could be at any distance without losing clarity as long as the lens and mirror don’t change. If the distance between the lens and the mirror were to change for some reason I think it would go out of focus and need to be adjusted. That would explain why when BonMul tried it on the wall the picture was crystal clear.

      That’s that I think, I hope it makes sense.

      -chuck

    • Hits Singapore » Blog Archive » The 100-inch Rear Projection Television Upgrade [DIY] Says:

      [...] it now runs at lights-off brightness levels. You know, like a cheap projector or something… [BonMul via [...]

    • Bonj87 Says:

      What is the part number for the screen you bought?

    • Mr Bob Says:

      Excellent idea!

      There are 2 focusses: electrostatic at the focus block, and mechanical at the lenses, secured by the wingnuts.

      The electrostatic would not change. However, the mechanical would, and greatly at that distance. I would recommend the Cantilever technique for getting the optical/mechanical right again.

      The overall light level would be a factor, because the bigger the screen, the more dispersed and thus lower the light level becomes. With the 7″ guns used in this RPTV, the light level could be reduced by half, with double the screen size. 9″ guns, like used in the Mit 73″ and one of the Mit 65″ models and all the older Zenith and Philips/Marantz 65″ models, would deliver 9/7 more light output.

      The aiming of the outer 2 guns might also be an issue, tho if it works, it works! The centering on the guns themselves on the CRT faces would have to be readjusted at the very least, tho. Found that when I shimmed my 73″ Mit up towards the mirror by 1.5″, exposing lots more of the CRT face to the screens than before.

      Speaking of which, this gives you the ultimate opportunity for overscan reduction WITHOUT having to reduce your height and width inside the service menu, and all the resultant corrections that need to be made when reducing overscan that way. This way you can keep your picture where it is on your CRT faces, with only minor mopup needed, compared to the major conniptions of the sm-only way of doing o’scan redux.

      Haven’t read this whole article, but you would definitely want to be using the same TYPE of fresnel/lenticular sandwich as is used in all CRT RPTV tech, to be sure and capture its light-gathering potential. Just a frosted screen would not gather and direct the beam properly like the classic f/l sandwich does, you’d have way more scatter than in the classic RPTV sandwich, which DOES beam the picture right at you, maximizing your light levels. I find RPTVs have at least double the light levels that front projection has, shooting at a semi-reflective screen, which disburses the light in all directions.

      Awesome project!

      Mr Bob
      http://www.imageperfection.com

    • BonMul Says:

      >> Bonj87 asked: What is the part number for the screen you bought?

      They don’t have it anymore on HTDepot.com. But if I were to do it again, I would not buy a screen. I would buy rear projection cloth on eBay and simply staple it to the wooden frame. It would have cost just 50 bucks or less.

    • BonMul Says:

      To Mr Bob:

      Wow, that some technical info!! Thanks for stopping by.

      The brightness level is not that bad, Its watchable with a florescent light on. When I turn off all the lights, the brightness is awesome.

      I agree with over scan advantage; But I have multiple sources connected, like media center PC that over scans, but I adjust the screen for PC, TV picture is under scanned. So have to find a middle ground.

    • Mr Bob Says:

      I just realized that for the project above, to have o’scan redux you would still have to shim the CRT array forward towards the mirror. Otherwise the t/b/sides of the optical cavity cabinet would confine the image edges and get in the way of the entire pic being able to hit the screen.

      If you leave it as it is, only most of the available CRT face area is being used/viewed. Shimming it upward where it’s mounted in the RPTV chassis would push the image forward and out of the optical cavity, and allow the entire usable surface of each CRT face to be utilized, only limited by the positioning of the image on each CRT face. On this kind of set, you can’t even think of changing the actual angle of the CRTs themselves. To do so could expose you to all sorts of scheimpflug considerations, which affect how completely the focus is across the CRT face in all directions.

      Mr Bob

    • Mr Bob Says:

      Chuck said:

      “The image comes out of the lens and is reflected off of the mirror which then is displayed on the screen. The image only has to be in focus where it hits the mirror for the picture to be clear on the screen. Really the screen, or whatever you are projecting it on could be at any distance without losing clarity as long as the lens and mirror don’t change.”

      Sorry Charlie, gotta diagree with you there. The mirror has nothing to do with the focusing. The focusing would be the same whether there were a mirror there or not - the lens to screen throw distance would be identical in both scenarios.

      Where the mirror is, everything is out of focus at that part of the light path.

      The lens to screen throw distance is what is fine-tuned by the lenses, which involves loosening the wingnut, refocusing and then tightening it again.

      Again, I recommend the Cantilever Technique for the nth degree of precision in optical/mechanical focusing.

      What didn’t change in focusing with this project was the electrostatic focusing of the focus trimpots of the focus block.

      The optical/mechanical focusing would be WAY off once the throw distance had changed by several feet as in this instance, and definitely need to be refcoused. Unless it was out of focus in the first place and adding a few feet of throw distance put it exactly in focus.

      But being out of focus OOB is rarely the case with a Sony CRT RPTV. Sony’s the only brand I can say that about, after more then 20 years as a professional calibrator.

      Mr Bob
      http://www.imageperfection.com

    • Mr Bob Says:

      Just realized this is not a CRT RPTV, it’s a single lens one. Must be LCD or something.

      Modifying a lot of what I said above…

      This CAN be done with CRT tech, but a lot more things have to be taken into consideration. This DOES explain why the brightness is still usable, and why the focusing stays roughly the same, with such a small, single aperture…

      Mr Bob

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    • BIG POP Says:

      just a quick question can this project be done with a 50″ toshiba color tv yes projection but you had a one lense i think mines is older cause it has three lenses red blue yellow. can it be done?

    • BonMul Says:

      BIG POP asked: “just a quick question can this project be done with a 50? toshiba color tv yes projection but you had a one lense i think mines is older cause it has three lenses red blue yellow. can it be done?”

      BonMul answers: I don’t know. its difficult to guess. Your best bet is to remove the screen and project it on a wall and see if you get bigger picture in focus.

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