Single white line horizontally across the middle of the screen. What does this mean? Model # DS27530

Hello
The vertcial output section in your TV is faulty. It may be either to a voltage loss to that section or an IC failure. Normally IC in this section will fail in most of the tVs. Vetical output IC can be located on the main board of your TV, normally screwed on to a metal heatsink to radiate heat from it while working. Locate this IC, and resolder all of its solder terminals by applying a little more solder, wthout making any solder bridge short in between adjecent solder terminals. If ther is any loose soldering, it will be cleared out. If this does not helps you measure the voltage that comes to that IC. If this is also found normal replace the IC. OK.