This is getting all too common on these elcheapo TVs. The patterns are sometimes generated on the T-Con, sometimes on the combo board. A first possible step could be to remove all inputs to the T-Con and supply it with 12V at the T-con fuse. If the patterns persist, then it's the T-Con likely at fault. If they vanish, then the main board is likely and replacement is invariably the only way to go. Bruce
