Samsung UE22D5003BW power supply board failure

An IR photo is a bit complicated; I doubt a smartphone can do that... rather, a good camera with a large sensor and a good lens... and surprisingly, some webcams...

-- Many manufacturers put filters that block IR to avoid distorting the natural photo... so that's not good...

-- To see if IR is captured, test the TV remote facing the lens... you should see the flashing LED sending its codes when you press a button... more or less clearly depending on the devices.

-- You can add a selective filter that will only allow infrared to pass through, unlike the one from manufacturers that blocks it.

-- The exposure time is longer than for a photo... let's say from 20 seconds to 1 minute; so you need a tripod that doesn't move at all...

-- Dust and tilt affect the visual measurement... several slightly shifted photos can give a rough average...

--- Otherwise, you can rent a thermal camera... touching gives a hint as well, and the temperature sensor (electronic thermometer) has the problem of taking 20 seconds to stabilize in temperature...

That said... you shouldn't focus too much; the temperature isn't the same for all components. It's important to know that a small component (capacitor, resistor) doesn't heat much... while a large transistor from a switching power supply can be around 70° and that's normal...
However, nothing should exceed 100° overall.

-- To test a power supply, you need to disconnect it from the TV circuits and connect a corresponding consumption resistor instead... maybe a little more... and measure the current with an ammeter... if it's the power supply that's the issue, the current should rise, then drop, and repeat in a sawtooth pattern... after that, you need to find... or change the board.
Often, these power boards carry a manufacturer's reference (subcontractor); it's not Samsung..! It is mounted on several brands and can be found at very variable prices on the Web, especially eBay... need to check.

There you go...

Hello,

when I turn on the TV, the SAMSUNG brand appears as usual and then disappears. That's when it's idle.
When the TV is plugged in, the program is visible, but after 1 or 2 minutes, the TV turns off and then turns back on.
So we can watch a movie with interruptions every minute or so.

How can I find out what's wrong? Thank you.

Let's say that on a forum, and without any measurements or diagrams, it's still a great improvisation that's close to laying on of hands.

So, in order to know what's wrong, it's not obvious at all... except in specific and blatant cases.

I would say that I suspect the backlighting of the panel... a pair of LEDs that may have short-circuited... it can be repaired!... but professional repairers don't do it, it takes time, you have to open the panel, and the result is uncertain... to get an idea, you need to be in the dark, have no reception (the screen is uniformly blue or white), and take two or three well-centered photos that capture the entire screen... or a video lasting two or three minutes... with no light saturation in the photo.

Then, you view it image by image, looking for the area that is poorly lit or deficient... this indicates the area of faulty LEDs... it's often more visible during transition moments, just before switching to black...

If none of that is present, the LEDs are not faulty, and the problem is elsewhere... You can look for hot spots on the boards (see an infrared photo)... also look for signs of burning, black resistors... internal dusting with a dry brush... to remove spider webs that cause arcing... those little noises too (little "clicks").

So here are some indications, but it is not the scientific method (with diagrams, computer and testing programs, oscilloscope, etc.) and the knowledge of circuits and technologies.

It's not the backlight. The image is good. I have a strong feeling that the problem lies in the power supply board.

I like your idea of infrared photography. But I have 2 questions:

1) How do I take IR photos? I don't have that camera. Unless I can find a way to transform my smartphone...
2) On a board filled with components that heat up, how can I detect a specific "hot spot"?

Actually, the solution suggested to me by the RAM technician-seller (PARIS-NATION) was the best one.
There was indeed nothing that indicated a malfunction: no "bulging" capacitors, no burnt components, the circuit was perfect... the tested diodes were good.
In short, since I suspected the power supply board, I asked him what he would do in this case. He then advised me to first change the 2 MPX capacitors and then possibly all the others.
I bought all the capacitors (half a dozen for a few euros) and started by changing the two MPX.
My first attempt was a mistake - I tried the TV without connecting it to the Freebox or connecting the antenna.
And then the brand name appeared and then disappeared as before... the TV was turning on and off.
Finally, I decided to make another attempt by connecting all the cables.
And there! Miracle! It works.
There you go... so perseverance is key.
Happy repairing to you!

OK, thank you for this feedback...

Indeed, in statistics, it’s usually diet that is most often to blame.

Best wishes.

Thank you. You too. ;)