If the set has "grainy" video, verify the sources first. If they are good, check the OSD. if that is fine, narrow the inputs if possible. Digital noise will show up as artifacts that customers will describe as "Grainy" and can occur on the HDMI inputs. If this only occurs on the HDMI inputs, and you know the sources are good, replace the main board. Also check external HDMI Cable is < 40 feet.
