There are black spots all over the screen with mu benQ joybee

SOURCE: Hi there my benq dlp

This is caused by dust on the lens assembly. If you can remove the lens, clean the surfaces with a lens cloth. That should resolve the problem. It is possible that the there is dust in the optical pathway inside the unit as well. If the cleaning of the lens does not resolve the problem, the unit should be brought in for a professional cleaning. It is not suggested that anyone open up these units as there are fine adjustments that can be changed internally easily that could result in convergence problems.

Dan