Then it’s very probable the DMD board, you see that board acts like the brain of the tv, it gathers all of the elements that compose the picture you see on the screen (light, color, pixel distribution, sound, etc.) so when black or white dots appear on the screen it means the distribution of the picture is not correct, thus the one in charge of that is the DMD. See if you can buy just the board, search it buy part number, if unsuccessful then you’ll have to buy a new light engine with DMD included.
SAMSUNG 61" DLP - HL-R6167W - Living Room
SHARP 46" LCD - LC-46D62U - Master Bed Room
DYNEX 32" LCD -DX-L32-10A - Kids Room