Samsung LED TV UN46ES8000 powers on briefly then shuts down. Does anyone know what the issue is?

I think an LED problem is more likely. The LED strips are usually powered by a driver circuit on the power supply board. You can check this with a bright flashlight shining on the front of the display at about a 20° angle from parallel to the display. If you can see the picture or the menu with the flashlight beam during the "dark" period, the problem is NOT likely to be the T-Con board.

You can also look at the back of the set with the cover removed - most sets have a number of vent holes in the back plate through which the backlight can be seen when it is on. If these holes go dark when the TV goes black, the backlight is being turned off.

When the screen is lit, take a picture quickly and look for dark spots. Maybe one of the LEDs has a partial short that shuts down the LED power and triggers a retry cycle. If so, after a while it will burn out and then the entire LED strip will be inoperative.

Pavers Saplay fold

With the cable unhooked that goes from power to main board that only tells the backlight section of the power board is working without regulation or overload protection, I suspect you have some bad lamps and overload or over current is shutting it down, of the issues I see with no backlights on Samsung sets about 95% of the time it's the backlights causing the issue

It sounds like you may have a couple of issues, it's normal for the backlights to come on if the main is unhooked but the flashing sounds like bad lamps. The 5 volts is standby voltage, next step is measure the PS_On pin when you turn the set on and see if you get around 3 volts there, if you don't you have a main board issue.

The issue is one or more diodes in the back light are bad and the power supply is sensing the change in current flow and is shutting down. Finding the offending led's can be a tedious job. Pull the strip out and use a tester on each led or just replace all the led strips

The first things to try are of course the simplest. If you have a picture on your TV but no sound, the problem might be as simple as having the “Mute” button the remote having been accidentally pressed. Grab your remote and unmute the TV by pressing the “Mute” button again.
Next, check what the input setting is on your Samsung TV by hitting “Source” on the remote and cycling through the available inputs. If your Samsung TV’s source is set to a component that you don’t have set up, then there won’t be any audio data coming in to be played.
Do you ever use a headset on your TV? Gamers, in particular, might be using a wired set of headphones plugged into an audio out jack, and if the headphones are plugged in, then any audio is being routed to that equipment, and you might not hear the sound playing if you aren’t wearing the headset. Assuming you never use a headset on your TV, check the headset port for any debris. Your TV may pick up something in the port which won’t allow the audio to route properly.
Finally if this does not work,you can try the old school way...unplug the your TV for about an minute.

If you wish to get some details; check the site linked here. Pull up older posts. http://electronicshelponline.blogspot.com/
Faults & possible causes to LCD screen are given with illustrations. You can get an idea about the fault to an extent.

SAMSUNG BN44-00807F L55S6R_MHS BN4400807F POWER SUPPLY /LED BOARD https://www.abctay.com/abctay-samsung-bn4400807f-l55s6rmhs-bn4400807f-power-supply-led-board-p-4398.html

Back light control board

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