Tv picture. it is sony model kv-g21m1trintron color tv. sound is ok. the problem is, the picture.

Question

it is sony model kv-g21m1trintron color tv. sound is ok. the problem is, the picture. it starts almost after 10 mins and it has white horizontal lines ( strips ). the colors are not as good as they should be also. can the screen be the cause. what else cause could it be? thank you!