I,ve got a red spot in the screen
i replaced the bulp but stil have the problem
it is most likely a burned polarizing filter. There is a polarizing filter on the blue light channel and another on the red channel. When black, or other dark colours are displayed, the red polarizing filter is supposed to block ALL of the red light being projecter. If the filter is burned, some light slips through and creates a red tinge on the projected image. If the red tinge only appears on dark images, but is absent when the images is completely white, a damaged filter is likely the problem.
Seems its hard to buy them. Best bet is probably buying a broken projector from ebay and stealing the filters out of it.