(Vestel) Telefunken XF43G511 - Thermal problem

[Unimatrix]

Hello,
I came across this forum because I need some advice about my Telefunken XF43G511 TV. It is originally a Vestel device. For some time now I have had the problem that the TV gets a black screen when the electronics are heated up. The backlight is still there and the sound still works. It's just the screen itself that goes off. When I switch off the TV and it cools down, the TV works again after a while. Could you please give me some advice on what could be causing this problem? I have also attached some photos of the electronics.

Kind regards
Thomas

[Unimatrix]

I have made some progress in identifying the problem. The 12 V voltage of the power supply is too low. It only supplies 8.8 V. Sometimes the voltage rises to 9.2 V and then the screen switches on. A Vestel 17IPS62 power supply unit is installed in my television. Can anyone give me a hint as to what could be faulty here?

I have checked all the diodes, capacitors and transistors with my multimeter and there is no short circuit or anything else suspicious. However, I also have oscilloscopes that I could use to check the voltage signals. But I haven't done that yet.

When I unplug the cable for the LED backlight, I have perfect 12 V again! And the display also works again, which I check with a torch. Is it possible that there could be a short circuit somewhere on the LED backlight? Can I check that with a multimeter?