Samsung UN65NU6900F - Sound and backlight but no picture

[uniram]

Hi, I am trying to get this tv working. I hope I can explain this clearly, but if not, please ask and I'll try to clarify.

I got this tv and it had vertical colored lines across the entire screen. I also found that if I touched the left cable from the main board when it was connected, I got a squeal from the main board and the vertical lines changed to noise.

I tested the SMPS and all voltages were correct, as far as I could see. After that, I disconnected one of the cables from the main board (the main board and tcon board are combined in to one) to the panel to see if one or the other worked correctly. Neither one did (see attached images) though I found it weird that the screen looked basically the same - left side dark and right side white - whichever cable I disconnected.

After disconnecting the cables and then re-connecting them, the tv now does not have anything at all on the screen. No vertical lines, no noise. The backlight is still lit and I get sound though. I also found that touching the left cable now does not produce any noise.

So, my main question is, how can I tell if the issue is the main board (what I suspect right now) or the panel? Also, is there anything on the mainboard I can check electrically to see if I can figure out the issue? I haven't been able to find a schematic for the main board (BN94-12873J). I have attached a good pictures of the board top and bottom (from ShopJimmy).

Any help would be greatly appreciated! Thanks, Steve

[uniram]

Re: Samsung UN65NU6900F - Sound and backlight but no picture

Here is a closeup of the connector and surrounding circuitry. Since I have no schematic, I'm hoping to be able to test this and figure out what voltages should be on what pins and possibly what components are bad.

[rpw]

Re: Samsung UN65NU6900F - Sound and backlight but no picture

Hello, I've been fiddling with a similar model and came across a file that you may find helpful. It's titled "Samsung Panel Scree Repair Procedure V 1.7". Here's the link. https://kupdf.net/download/samsung-p...5377328edb_pdf

[comptek]

Re: Samsung UN65NU6900F - Sound and backlight but no picture

I would try taping up the clock (clk) lines
Normally works for me try both sides though
There plenty on YouTube showing how to do it

[Pooshoes]

Re: Samsung UN65NU6900F - Sound and backlight but no picture

Did you end up finding a solution? I have the same model that is giving me trouble. I try blocking pins but can't find the right ones to cancel the error and allow the voltages to make it to the panel to turn on the screen. These ribbons have a different wiring than the usual fat ribbons for which I have a pinout for.

With the screen ribbons disconnected all voltages check out fine on the mainboard (I might be able to help you out if you need some information what shows up where) but I can measure my 3.3V and 27V that would normally head to the panel. When connecting the ribbon the voltages will no longer turn on.

I don't have any shorts on the panel that I can measure, but trying to figure out what handshake needs to take place or be blocked in order for the voltages to get sent to the panel so I can figure out what to do next.

Thanks!

[Unspun01]

Re: Samsung UN65NU6900F - Sound and backlight but no picture

I have same TV. UN65NU6900F. Terrible TV. Most likely a bad panel. covering clock lines may or may not work. you will need to remove the metal covers at bottom of screen and inspect the scalar boards at bottom of panel. There are 4 I think. Call them 1,2,3,4 from left to right as viewed from rear.

They are connected to each other with small ribbon flex cables. 1 to 2, and 3 to 4. #2 and 3 connect to to TCONN as you have seen.

On my TV, I would get backlights and no image at all times. some rebooting maybe.

I could get audio to work and no rebooting by disconnecting ribbon cable 1-2. A closer inspection under magnifying glass showed visible arc/burn damage to one of my tab bond flex cables from scalar board #1 or #2 (I can't recall) to the panel. Not repairable in my case.

I advise carefully removing the metal covers and inspecting your scalar board to panel flex cables. Also, they should get warm, but not searing hot. My bad one was very hot and I couldn't hold a finger on it for more than half a second.

Try to check your TV and let us know.