Question about InFocus LP70+ Multimedia Projector

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Tranlucent dark spot on Optoma image. Looks like something is on the lens.Off center--top to bottom. Cleaned lens, blew out case, changed bulb, still with dark spot.

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  • wizbaugh Dec 05, 2009

    This is an Optoma EP721, would this be the same?



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Is it an optoma or an infocus? if it is the infocus, it needs to be replaced. however, to replace it, you need to remove the entire optical engine. now off of that, remove the clorwheel and clip, the main board, and the tunnel (on this model it is called an integrator rod) assembly. to get that out, remove the 3 tap screws and the large screw. once you can slide it out, remove the foil from the front, slide out the inside tunnel assembly, remove the clip, then the tunnel. because the clip is an exact fit, you cannot have anything on the tunnel that increases the size. reverse the instructions to reassemble (but you will need to replace the foil with a new one). warning: you now need to realign the tunnel using 2 of the tap screws. if you have not done this before, it is very difficult and dangerous, as you need to have the projector powered on and the screws are way inside next to the power supply. there is a risk of electrocution and damage to the projector. best bet- send it in to an authorized infocus service center for repair. try av solutions in ny. they're really good.

Posted on Dec 01, 2009

  • jasbo
    jasbo Dec 09, 2009

    it is not the same as the optoma. it was under the infocus lp70+, so i assumed it was. but the problem is still the light tunnel. the installation is different.


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This is a common problem with InFocus projectors!
The Light Tunnel / Pipe has begun to collapse.
The Light Tunnel is a series of 4 first surface mirrors that make up a square box approximately 30 mm long with open ends. This part is mounted within the die-cast optical assembly directly behind the color wheel.
This tunnel is a conduit to concentrate and couple the light energy from the color wheel to the first objective lens in the DLP engine. Is is held together with an adhesive that breaks down in time from the intense heat causing the glass mirrors to expand and contract with these extreme temperature variations.
(Cutting to the Chase now) The Light Tunnel needs to be replaced. This is rather tedious on the LP70(+)
And most likely a service facility will just replace the DLP engine. However depending on your skill level you may be able to figure it out and perform the repair yourself... It can be re-glued with a high temp adhesive (not with crazy glue) and work just like new!

I would suggest an "EASTMAN" Hi-Temp adhesive.

Good Luck!


Posted on Nov 29, 2009

  • David Hammack Sep 19, 2013

    I have a similar issue on my optoma gt700. I took it apart to inspect the light tunnel but it appears to be okay. Any other possibilities?



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