Samsung UE50RU7170 not booting /no picture

[Aeisens]

Dear all,

My issue is the following:
Tv suddenly started to make Strange things and went out. After disconnecting power and restarting, it tried to start but failed. After each attempt it got worse and worse. Now only the Stdb light is on and it is not booting.

I checked the power supply -> Backlight on when disconnected from mainboard, so I guess Power supply is ok.
Additionally the upper right part of the main-board makes some whistling noise -> probably issue there and therefore issues with booting

Question 1: Where should I start to Look for the faulty part on the mainboard? BN94-14112H

As I Could get my hands on a used mainboard from the same model (Both UE50RU7170UXZG but mine is Version No. 02 / URU 7100, while spare Part is from 05/URU7100) I tried a new Mainboard.
Result: TV booting + Sound from settings, but no picture.
when comparing the boards I realised they were different Versions (BN94-14112H vs. BN94-15022A)

Question 2: How to Check whether my issues with the new board are caused by different Version, or by Further issues with my TC Board or Panel?

I hope somebody can help me.

[lotas]

Try to move SPI Flash W25Q80V_IC1603 (T-CON firmware) from the original board to the new one.

[Aeisens]

Thanks for the Input.
I tried it but still the same issue.
could I Try to Flash new Firmware with USB?

[lotas]

Are the positional resistors in the T-CON area installed identically on the motherboards? How can you install a new firmware without an image? Install a jumper and try to connect the LVDS cables one by one and see if an image appears on which side.

[Aeisens]

You mean the marked Area?

I Could Download Firmware on usb and Hope to find a Video Tutorial what to Click when —> no Picture needed

with the Jumper I got. on the Left side a white screen

[Diah]

50 size panel are rubbish over all brands.

[Davi.p]

How are composed the panel strip boards (may be hidden under metal frames)?
The area where you hear noise is the tcon area, check every discrete semiconductor and every cap for shorts.. check also for shorts the diodes and caps on the strip boards

[howardc64]

Additionally the upper right part of the main-board makes some whistling noise -> probably issue there and therefore issues with booting

Something that make whislting noise has to be bigger in size. In your circled area, there are 9 inductors (1 square, 8 octagon silvery parts, right most 8 might be for T-Con) Inductors are coils and maybe most likely candidate for the sound.

Maybe rig up something to see if can isolate the noise to the part. I think the inductors may not be isolated and they carry voltage so careful with touching with metal to listen for noises.

Can also test the voltage on the inductors and post them. Many T-Con inductors carry unique voltages so can probaly identify if missing. Volt meter negative on board ground or even TV metal chassis, positive on either end of the 2 inductor connector.

Here is UE50M (2017) service manual ( link ) its not as new as your UE50R (2019) but main board have a lot of similarities. p89 shows its main board with similar T-Con board location on main. This board has 2x 96 pin panel flex connector like yours. Service manual labeled all the signals. I don't know if signals are identical to yours (maybe check all the labeled ground pin to see if in the same place on yours) You need a real fine probe tips for this due to small pin pitches. All the T-Con voltages are generated on main and sent to the panel. So the inductor(s) output will eventually show here. You can see from UE50M panel flex connector with voltage labels (p90-92) There are 17, -7.5, -11, 8.5, 3.3, 1.9 volts etc. Ignore all the *_CH*_A/B +- lines. These high speed differential signals to feed pixel data and not your problem source. Note its not easy to read the signal chart to match the physical connector. Sometime its transposed so make sure you have a clear orientation on pin 1 on the board and the table.