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news from the lab…
Black and White Video Projector
Categories: Hardware hacking, video

I was thinking about this one since doing this exhibition for the ethnographic museum in Zurich: Why not just rip out the colorwheel of a DLP projector to make it black and white? Should be easy and should work, no?

It works, and I could stab myself 100times – why didn’t I have the courage to do this back in 2007 for this expo. I was projecting beautiful b/w pictures by Michael Oppitz with two beamers per screen – but black and white with color beamers is never quite black and white, and I found myself creating correction masks in photoshop by hand for every single of the 14 projectors. The horror….

Then, I was short in time and I didn’t dare to rip open the brand new projectors, voiding warranties, etc.. but I think that’s what I should have done in the first place…

Now these Acer XP1250 are probably the worst video projectors I’ve ever worked with (unfortunately they were my choice). Really shitty optics: strange dark zones in the image, you cannot zoom without changing focus, and it’s all so loose that things move by themselves. But you always get what you pay for, and then they were really cheap!

So today, I still got four of them, they’re still alive, but I’m not afraid to tear one apart. For science!

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After tearing off the shitty plastic housing. Color wheel is right there in the front.

 

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Like I thought: there must be a sensor of some kind, that synchronizes the speed of the color wheel to the image refresh rate / refresh rate of the DLP (or the other way round?)

Basically it’s just a 1cm strip of black adhesive on the drum of the wheel’s motor, and a reflex light barrier.

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I removed the sensor just to see what happens: Projector starts up, lamp goes on for a while, then all goes off again. Exactly what I thought: the projector must be quite uneasy if it doesn’t know how fast the color wheel is spinning.
So I’ll either have to take out the colored glass and keep the motor with the black tape spinning in front of the sensor – or generate fake signals in place of the sensor…

 

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The XP1250 color wheel has a yellow and a white section in addition to the blue, green and red sections…

Finally I found there’s enough space to mount the color wheel outside of the light path – no need to take away the glass, just let the whole thing spin somewhere it doesn’t bother us. That way, the whole process is even reversible and I could transform the projector to color again (If I hadn’t scratched the glass terribly while trying out – it started to spin up and grinded terribly on the pcb…)

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Quick fix to get the wheel out of the light path:

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Will try again tonight when it’s dark, but as you can see the picture gets a lot brighter. (Same signal through a splitter to 2 XP1250s, left the modified one, right a normal one). To me it looks also crisper, more focused.

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3 Comments to “Black and White Video Projector”

  1. Franck says:

    Fantastisk!
    I dreamed about it, a BW beamer.
    I’m wondering if i take my chance on my brand new 6500 lumen Mistu VP ­čśë

  2. flo says:

    yes.hehe. endlich.super.bin dann sehr gespannt.
    hmm.
    jetzt sollten wir das ganze noch mit e-ink display machen. denke dann haben wir wirklich s/w

  3. mohamed khalifa says:

    when i did these tips the color wheel was rotating continuously,no blinking of indication led of the lamp,and no light is progjected from the lamp.so what is the problem :( ?

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