Multi colored vertical Lhmd bes

Bakr Ragragui those are usually a sign of a bad panel. Since it used to get better when your unit warmed up it is possible that this is caused by a cold solder joint. You would have to take the back of and visually inspect the boards to see if you see any obvious damage like a bad capacitor etc. Post some images of your boards with your question so that we can see what you see. The main board is where I would check first. Please verify that your TV is a Samsung LN46A530P1FXZA