Barco DP-2KP yellow patch Revisited

[Harcharan Singh]

Hi
I have a Barco DP 2KP projector and had developed a yellow
patch. It was suggested that its a LE issue. Today I did a test
and found that the yellow patch is only on white test pattern .
On Red, Green and blue test pattern that patch is not visible.
Please see the attached pics. I somehow still believe it is not
LE issues.Any expert advice on this will be highly appreciated.
Thanks
Harcharan

[Marcel Birgelen]

You need two colors in order to make yellow: red and green. So, a yellow patch in a white surface is due to the absence of blue in that patch.

It's a bit hard to spot, also due to the bad image quality and high compression, but your blue looks like it has a somewhat gradiental drop-off in the top-left corner, which could explain the presence of the yellow patch.

It's hard to give any definitive diagnostics based on this, but I suspect there's something wrong with the blue DMD, maybe the alignment isn't correct or it's dirty. It could also be dirt or damaged spot on the prism, where the blue light enters or exits it.

[Harcharan Singh]

Hi,
Thanks for you reply.
On the blue pattern I am not seeing any patch when viewing from projector. The image that I have posted may have a little problem.
If you are predicting is the case, is there there anyway a Barco Tech can clean the Blue DMD or dirst on prism locally or the LE had to be sent to Barco for cleaning.
Harcharan

[Marcel Birgelen]

In order to clean the DMDs and/or even the prism, you need to open up the light engine. The light engine is a "sealed design", that's where the water cooling is for too, so it can remain sealed. If you open it up in the field, dust and dirt from outside can enter and make situations worse. Dust settling on top of the DMDs protective surface can even burn into it and permanently damage the surface. So, I'm not really a supporter of doing this in-the-field.

[Marco Giustini]

Harcharan

You won't see a "patch" on your blue pattern: you would see a darker area. If you reduce the blue component on a white picture you would get a yellowish tint.

Are those MCGD colours? First I would check with uniformity correction disabled. If it's better, then you just need to re-do your uniformity correction. If it's unchanged... well, you may still want to re-do your uniformity file but it will likely just brush the dirt under the carpet!

[Carsten Kurz]

@Harcharan - please, before you start doing anything - take a closer look at that projector. Chances are you missed the SONY logo on it. You might be turning the wrong screws! It's an industry-kown fact that machines showing color blotching can not be DLPs.

I mean, BARCO and SONY, these logos look very similar from a distance...