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LED conversion in a DLP projector

  • Calcugus Thursday, December 16, 2010 7:33 PM Reply
    Would this work with sku.50026 and a 120W electronic halogen transformer running 12V tucked inside a DLP projector? (by removing the ballast board there is a lot of room created...

    I've managed to bypass the lamp check on a Viewsonic PJ402D. Tested with CRE R2, SSO P7 etc. It is evident that the light pipe loves a point source of light or tight beam optics. However all produce an image that is only suitable for zero or no ambient light.

    What optics would I use with this LED to get more light into a 10mm spot about 50mm away from the color wheel?
  • frollard Friday, March 25, 2011 6:51 AM Reply
    I would also like to know this!

    My dlp Optoma will be dying eventually and I ought to figure that out.

    Optics wise you have plenty of room for a concentrating reflector that gets the beam down to about 20 degrees...then you need a convex lens that shrinks it inwards - lensmakers equation would tell you how to make the beam focus 'about 1 cm' on the colour wheel, and another concave to make the beam output parallel so it doesn't scatter after the colour wheel. Crazy sauce.

    I'd like to know how to trick the motherboard into thinking a) the ballast is still there and b) the bulb check completed...
  • Calcugus Friday, March 25, 2011 7:29 AM Reply
    Yeah the ballast trick is simple. Basically in the Viewsonic and most other projectors, the ballast has a management circuit built in. It "reports" to the main board by tying a line to GND if something is wrong. Basically you need to listen on the 3 or 4 pin connector coming off the ballast and watch for a line going from 3.3V to gnd when the lamp fails. Then tie this line to 3.3V permanently using one of the 3.3V supply lines.

    Worked a charm on my viewsonic.

    Been thinking about using 18650s in a battery pack to make the projector 100% portable....now wouldnt that be just sweet...
  • marc6666 Wednesday, April 20, 2011 5:37 PM Reply
    What Calcugus says it's just so. I used sku .13618 for optics for modding my Nec vt470. Work just fine. THe best thing around so far is the xm-lt6 885 Lm. Always on the lookout for anything new, small (definately need a point source light) and powerfull in order to increase the amount of light in the tunnel.
  • ItalianBoy Thursday, June 30, 2011 9:05 AM Reply
    @marc6666: I'm planning to do something very similar. How is the light output of the projector, compared to a "normal" one? I know it's less bright, but how much? Do you think it reaches at least 100 lumen?
  • marc6666 Thursday, June 30, 2011 9:20 AM Reply
    Well, to put it simply, you have to be in a very dark dark room in order to watch anything normally , windows covered and all. Never been able to measure the final lumen output, but mine it's supponsed to put out some 885 lm at 3a, my ps only provides 5v & 2.5a to the driver so I guess I could push it a bit more. I think it's somewhere 500 lm or so. aLL and all, depends on your situation., It is viewable my son uses it to proyect the Ps2 games on a wall in a dark room so no complaints from him, allways biger and brighter than normal tv projection.

    Depends on what you use, you could get some 500 lms at the most I think, Still got to try it with a U2 emmiter I just got, driver and all, and give it some 4.5 v and see if it improves.


  • ItalianBoy Thursday, June 30, 2011 9:29 AM Reply
    I meant the projector output, which is always much lower than the lamp output. Well, I think that an XM-L powered projector should still be much brighter than those generic LED projectors that output 30 lumen at most. My target is, in fact, to mod a broken projector into a rechargeable lithium battery powered one.
  • holmerjhf Wednesday, June 26, 2013 4:05 PM Reply
    Hi Calcugus, could you try to explend how you to trick the ballast unit of Viewsonic that you have, because I have a PJD5112 but I dont understand how is the prossedure. maybe some picture about yous optocoplers, sorry for my english..thanks..
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