I had a Mitsubishi HC6000, and I found there is a green spot(tennis ball size) shows in the black scene.

I sent it to the service center and cleaned, yes, now I can not see the spot anymore, but now a new problem comes that I can clearly see the yellowish screen door!

This will bring a problem that in the dark scene, I can see some blue noise in the screen.

Does any one know what is going on here? Is that because cleaning the spot will make screen door more obvious?

I had a Mitsubishi HC6000, and I found there is a green spot(tennis ball size) shows in the black scene.

I sent it to the service center and cleaned, yes, now I can not see the spot anymore, but now a new problem comes that I can clearly see the yellowish screen door!

This will bring a problem that in the dark scene, I can see some blue noise in the screen.

Does any one know what is going on here? Is that because cleaning the spot will make screen door more obvious?


I think that you had a dust blob: a piece of dust that landed on one of your lcd panels or polarizers.

When you cleaned it, you removed the dust but perhaps left behind some reside on the panel. I would clean everything again but be very gentle and use an appropriate lens cleaning solution with a clean and soft microfiber cloth.

Thanks Lawguy for your help.
But I still have question: when I go close to my screen, I can see the screen door has color and the color has sequence, it is like one light yellow, one dark yellow then one white(no color), and this sequence spread on the whole screen.
I am not sure but I think it is too even for a dust.
Also I should describe more for the blue noise. when I watch 2.35:1 movie, then the black bar on the top and bottom will be blue, and the blue will gone either I raise the brightness or lower it. but that will make my picture either wash out or pitch black.
Not sure if any one meet it kind of thing before.

I think what you may be seeing is panel misconvergence.

The HC600 is an LCD projector that uses three panels. One is red, one is Green and one is blue.

It is very difficult for for manufacturers to align these panels so that they come together to for a perfect grid. Instead, there is usually a slight overlap among the panels. Thus, you tend to see some color fringing. typically the color fringing is either red, green or blue.

There is nothing that can be done on the HC6000 to correct this.

The blue color that you see on 2.35:1 material is likely a sign either that one of your polarizers is either dirty or defective.