White horizontal lines top

Check the backlight inverter board. Contact any service technician. If you wish to get some details; check the site linked here. Viewing it in "Mosaic" will make surf easy.
http://electronicshelponline.blogspot.com/

Please check your RAM

The vertical scan output stage is faulty. Check and replace damaged component/s in the vertical output circuit. Visit the site named 'Electro-help' for more details. Click this link. View it in "Timeslide" or "Flipcard" option, which can be selected from the drop down box menu by the [Sidebar] tag, at the top left corner of the display window. You can also click the [Home] tab to the latest updates. It will make search easy. There are more than 1350 posts to different brand TVs now. Pull up older posts there.

Check the ETB belt for a horizontal scar.
Next check your toner cartridges. One of the drums may have a scar.
Under DIAGNOSTICS Menu, run PQ Troubleshooting.
See if any of the colors give you the white line.

Because you said that only one line occurs, I'm inclined to go with the ETB belt.
Check it good for the horizontal line.

I have the same problem, but it's a vertical white line.  I have a BB Curve 8310.  From what I've researched on the web, it seems the LCD screen wud have to be replaced.

This fault is most likely from some worn capacitors in the vertical output section. An experienced service tech can troubleshoot the set, locate the defective capacitors, and change them for you.

Jerry G.

55hdm71 plasma hitachi vertical lins 3 red on right side what do i do?

Sounds like your monitor or graphics card may be going bad.

Set starts, horizontal and vertical deflection work, HT ok, crt heaters ok, but no sound or picture
I turned the G2 voltage up and noticed a white screen with flyback lines, frame ok. I detected two badly soldered double diode rectifiers in the secondary part of the power supply ! I checked all other joints, and everything was ok !! success
White horizontal line (no vertical deflection)
Check / replace R548, R549
Sound but no picture except for a couple of horizontal colour lines
Replaced the frame chip TDA8356, set now ok

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