You may notice that a large yellow spot is showing up on your projector screen while viewing a slide-show presentation or movie. The spot is projected along with the image and seems to appear out of nowhere. It may even start to grow larger until it completely covers the screen. This yellow spot indicates that there is a problem with the projector and you may need to replace or clean one of its parts.
Check the VGA cable to ensure it is properly inserted into the "Component video" port. The VGA cable is needed to display visual images from other devices such as a computer or DVD player. Sometimes these cables may be wired incorrectly, which can result in a yellow spot. Try replacing the cable if the problem continues.
Replace the lamp in the projector if needed. Check the lamp meter on the projector to see how many hours it has been used and how much time is remaining. Projector lamps last only for about 1,000 hours. A replacement costs about £195 to £260 in June 2011.
Check the filter and clean it thoroughly if dirty. When the projector's filter is dirty it will block airflow, making it overheat, which often produces a yellow spot.