Lines across the top of screen.

Without seeing the lines I can't be sure what your set has wrong, but here are a some possibilities:

If the lines are lines are confined to the top inch or two of the screen and the picture looks otherwise normal, the trouble is bad capacitors in the vertical output circuit. Fixable by replacing the bad parts.

If diagonal lines are across the entire face of the picture tube and the picture looks washed out, the trouble is often a bad capacitor on the 200-volt line to the picture tube. This may be on the main circuit board near the horizontal output transformer, or on the small circuit board plugged onto the end of the picture tube. Again, replacing the bad capacitor can fix this.

If your TV is actually an RCA, someone may have bumped a rear-panel adjustment. On the back of the TV near the bottom right are two small knobs. RCA left these adjustments exposed inside of putting them inside the set like other manufacturers. These sometimes get bumped if someone was behind the set cleaning, or if a pet got back there and hit them with a tail. The top knob adjusts focus, and the bottom knob adjusts something called G2 or screen voltage. If this gets turned up too high it can cause the faded picture and diagonal white lines. Turn the adjustment down until a black screen looks black instead of gray.

A bad picture tube or horizontal output transformer can also cause lines through the picture. If this is the case with your set, it's time for a new TV. The transformer is relatively inexpensive but labor costs aren't, and the repair bill may exceed $200. If the tube is bad, there's no point even considering repair. The tube cost alone exceeds the cost of new TV.

Hopefully your lines are easy and cheap to fix. Good luck, and thanks for using Fixya!

Hello
Set the brightness, contrast and colour control of that TV to minimum. Watch it in a dark room whether ther are thin white lines across the screen, at about an inch apart, from bottom to top of the screen. If there are lines, that TV needs screen control adjustments. That is, now the screen voltage given to the picture tube went high to some reasons. If you have confidence that you can adjust it, I will guide you.
Open the back cover of that TV. Locate the LOT [Line output Transformer], usually one red thick wire is connected to the top of the picture tube with the help of a rubber ****** and clip. In most TVs it can be located and can be seen as the back cover opened. There are two variable control, fitted, integrated to LOT. Normally the upper one is marked as focus, and the lower one is marked as screen. You shoud adjust this control to avoid these lines.
It is a live service, that is the TV must be switched on during this time, and take causion in every respect not hurt by yoursef and the TV. Keep the children away from you, and an other adult person beside you is better. A liitle turn counterclockwise will remove this problem.

leaky caps in vertical section.

Hi There,
Sounds like your Horizontal Output Circuit is leaking current causing diagonal lines across the screen. I hope this will help and thank you for using FixYa!

The original white line problem was caused by improper adjustment of the vertical size for which there is an internal adjustment. The current problem could come from two different sources, one an adjustment again, the other from a capacitor that is losing capacitance and gaining losses; = sick.
If you are fortunate enough to have a surviving TV repair in your area, none of these problems is expensive to find or correct.
Don't be surprised to find the only TV shop operating out of a messy garage since those of us doing this kind of service are dying off and the price one can charge for labor has shrunken to the point that a real business address is too expensive to have.  

Hi I had the same problem. Broken white lines across the top of the screen. This is called overscan. You need to go into the Setup menu, other settings. 16:9 overscan needs to be on. Hope this helps.It solved our problem.

if these lines are just at the top of the picture then i would suspect an electrolytic capacitor in the vertical circuit.

try to adjust the screen control in the flyback transformer. good luck

Those lines sound like "retrace lines" and several things can cause them. The most common are shorts inside the picture tube and shorted semiconductors in the video driver circuits. They can also be seen if the blue screen voltage is too high or if someone has tampered with the screen voltage control.

try adjusting the green screen control. remove the front bottom panel of the tv by removing any screws holding it in place. gently pull of the front panel, there are gromets holding it in place, you will be able to gently remove the front, just make sure you get all those screws. now reove the small wodden or plastioc panel. now you will see the screen/focus assy. check to see of the screen controls are the top 3 or bottom 3. adjusted the center screen it's the green one, the other 2 are the red & blue. it is best to adjust in a dark room where the lines will show up easier. good luck