Tv screen will go black after being on for a while

https://www.shopjimmy.com/tcl-55s403-complete-tv-repair-parts-kit-see-note.htm

I would suspect a problem with either the inverter circuit, or 24vdc circuit. I would start with checking the power supply capacitors. Look for any with bulging tops. Research shows your set is from the 2008 era, many sets from that time were built with cheap Taiwanese capacitors. I've repaired quite a few of the older LG LCD with your same problem. They all had faulty capacitors in the power supply.

The set will need to be properly diagnosed to narrow down the problem. You could be looking at a bad inverter, bad CCFL lamp, fault in power supply or main board.

Need s to be replaced the main board.

Most likely burned out lamp.

Do you have audio and if so can you change channels to hear other programs? If so ...you have a bad vertical IC. Have a tech turn up the screen control to see a white horizontal line. By your question I would say this will correct the problem.

i know your problem. its an inverter loose connection from CCFL to inverter output. back of your LCD inside the TV. try to remove and re-connect again. be sure no power and AC is unplugged. [email protected]

If your tv is flashing 7 times. Disconect audio module. It is on top of power supply. Turn tv on you will have picture. Conect the audio outout from the rear. To the aux. input of a stereo. Where you night control audio level. Or get a new audio board. Its is very expensive get only the audio amp I. C. The audio. part. No. 1-866-539-11

need the model number of your set in order to help, but it sounds like a problem with the light engines shutter

the light engine is defective and needs to be changed..this set is not that old..contact mitsubishi customer relations to see about having it done under a customer accomodation, as they have had a lot of problems with the engines