Samsung 70” 4K TU7199 - no image

[djdblaster]

Hi guys, I've got Samsung 70" UHD Crystal 4K TU7199 TV here with backlight present, but no image problem. I've used laptop with HDMI cable to play music off YouTube.

TCON board consists of three mini boards: left, middle and right board.

Diagnosis:
1. when TV is fully assembled, it doesn't turn on fully, rather just boot loops. Backlight comes on for few seconds, no boot sound.
2. disconnecting TCON big white cable on the Main board let's TV boot and play music through HDMI.
3. TCON cable connected, but left mini board disconnected, TV boots and plays music.
4. TCON cable connected, but right mini board disconnected, TV boots and plays music.
5. TCON cable connected, but left and right mini board disconnected, TV boots and plays music.

All this time, no image is present on the TV.

I've gotten an info that a problem might be within a mini middle board or the panel itself. Not sure how to diagnose that.

If someone has any other ideas, I'd be more than happy to hear.

[EazyBone]

Google fixing TV with tape. Try that on the"mini board" ribbons. It's not a fix but can lead you into potentially finding you have a bad panel

[Suslik957]

Вы соединили контакты на плате?

[djdblaster]

EazyBone I'll check that out.
Suslik957 Yes, the board is placed back in the housing, just as intended.

[Suslik957]

I had such a TV with a similar malfunction. First, you need to connect two contact points on the main board with a wire, and then try to disconnect parts of the screen. There will be no image on the main board without connecting the contacts.

[adamp91gvm]

i have the same issue with mine it just power cycles did you get this fixed ?

[nomoresonys]

I had such a TV with a similar malfunction. First, you need to connect two contact points on the main board with a wire, and then try to disconnect parts of the screen. There will be no image on the main board without connecting the contacts.

You had a separate/stand alone tcon correct? this tv has none.

[EazyBone]

You had a separate/stand alone tcon correct? this tv has none.

I think he is referring to a test that RJ has suggested and shown with similar Samsungs. He solders a connection to do the test

[nomoresonys]

Indeed, I know it well, it's done on stand alone tcon boards.

[adamp91gvm]

so ive managed to test it and filter it out to the left bottom screen board if i disconnect it ,it comes on missing a chunk of screen

[nomoresonys]

so ive managed to test it and filter it out to the left bottom screen board if i disconnect it ,it comes on missing a chunk of screen

Right, so try the tape "fix" if you have not already if no luck with that, might be a bad component on the panel driver board, post good focused pictures of them, the whole board.

[adamp91gvm]

yer i have its comes up with a line across the centre

[nomoresonys]

How bout those pictures? can use two pictures if needed but need the whole board in them.

[nomoresonys]

so ive managed to test it and filter it out to the left bottom screen board if i disconnect it ,it comes on missing a chunk of screen

Fire it up and see if any components on those boards are getting pretty hot, like kind of burn your finger hot.

[nomoresonys]

Suppose it could also be something like in this thread: https://www.badcaps.net/forum/troubl...digging-deeper

[nomoresonys]

Here's some more messing with similar problems, pretty good explanation of how the shorts can be about anywhere on those lines and results can vary widely, if you check the last comment there's a link to his continue video of it: https://www.youtube.com/watch?v=7HMGyt1nNgY

[nomoresonys]

Check the resistors on those boards, the expected ohms are marked on them, check the little mlc caps for shorts or very low ohms.

[nomoresonys]

Not exactly sure what T15 and T16 are because I don't mess with the driver boards much, but if they are tvs diodes, one or both could be the problem.

[adamp91gvm]

Got it back on with a slight few lines

[EazyBone]

By doing what