Samsung dlp tv black horizontal lines

I have a 55 Inch Samsung DLP tv, we have noticed black horizontal and vertical lines they are about 5 inches apart and are evenly spaced, they are mostly noticed on light colored back rounds, like a white screen, I called Samsung and as usual they said call a repair shop, I am very mechanically handy. Is there any repairs that I can do to fix this problem? Repairman wants $150.00 up front just to come to my house.