Sharp 20f640 focus problems

At the rear of the tv there may be two controls on the right hand side marked "screen" and "focus".If the set is newer,you will have to remove the cover and look to your right.You will see a dark object with a black or red wire coming out of it's top.That is your flyback transformer.On this you will find these two controls.Adjust your focus with the one so marked.Be careful to only adjust this control while you watch your picture clear.PROMPLY put the cover back.