I have a LG 60ls5750 television. On startup it works great, and then a minute later the picture feed is replaced with colored horizontal lines. Hate to scrap it as the rest of the TV seems solid.

SOURCE: Horizontal White Line

In your statement i found during switch on you get picture. Check whether in a few minute picture suddenly goes to the horizontal line or height reduces and then goes to line. If suddenly goes means change any zener diode in pumpup circuit. If it is not means LA 7840 ic getting imbalanced supply voltage i.e.,negative and positive voltage are not equal. Suppose only one vcc means supply resister getting high ohms and change the the supply resister.

SOURCE: Color line across the center of a black screen

Hi. this is caused by dry solder joints on the frame o/p IC. Resolder all legs of frame chip. Should sort that out.

SOURCE: Flicker-Blinking on picture

Too late now but I hope you had it serviced while it was still on parts warranty. With a couple of exceptions, service on those is by major pcb replacement.

SOURCE: Intense white & coloured horizontal line on black background on startup

I wouldn't attempt as the capacitors on a tv store around 25000 volts this is more than enough to kill you and they keep there charge even when the tv is off. Either take it to a repair shop or put that money towards buying a new tv - Do not even attempt to open the tv. (It sounds like maybe a tube has gone or the electromagnet that makes the beam move vertically is gone.

SOURCE: 40 samsung lcd picture problem

first check the power supply board for puffy capacitors. then change the t-con board on lcd panel