Troubleshooting TV PSU (help needed)

[victor]

I have a 21" AOC TV that is not turning on, the standby led (orange) is ON but when trying to turn it on, the led goes on blue for a second and it shuts off and goes back to stand by (orange).

There's a whine noise coming from the transformer.

I couldn't notice anything obvious in the visual inspection, while I know it is probably something wrong with the power supply, I don't know where to start.

I don't have schematics, but the circuit is fairly simple as it is a single sided board. I included the best pictures I could take of the top and bottom, and a combined top/bottom image.

From the quite loud noise coming from the transformer I suspect that it is not switching as fast as it should be, due to some dry cap, but it is just a guess.

Any suggestion of where should I start?

[victor]

Combined top/bottom picture

[DrGeoff]

The PSU could be shutting down due to a fault elsewhere.
What are the PSU rails? Can the PSU be powered without the external loads connected to check the rails?

Edit:
OK, I see from the SS overlay that you have a 16V and 5.2V rail to test.
And a few LED backlight rails.

[retiredcaps]

You don't state what model, but some of the LED TV exhibit behaviour similar to what you describe because one or more of the LEDs have actually failed.

Tons of info at

https://www.badcaps.net/forum/forumdisplay.php?f=31