Marks on the image can be very annoying. What causes this problem? How can it be fixed?
If you have marks on your image this is usually due to unprofessional cleaning of the internal parts of the projector. Look at the image below.
The lens is on the right. Behind the lens you have the DMD chip to the left. The light channel directs light into the DMD enclosure. If any dust gets into this channel marks will show up on the screen. Here you can see we have taped up the channel to stop dust entering the DMD enclosure.
So Here we have removed the motherboard, the ballast and most of the internal parts of the Acer projector. If a DMD chip is removed and replaced dust could get inside the DMD enclosure this will cause hairs, fluff or or other debris projected onto the image. This needs to be cleaned professionally. Never ever blast compressed air into the inside of your projector as this does not clean it it just moves the dust around and can create worse problems.