samsung un65nu6900f common problem, digging deeper

[Cornito]

Did you retest from the beginning, with the jumper between the 2 test points with only one side connected, to check if there still a side which is working normally.
On TV i've saved (dead since, i'll need to confirm that the panel is definitely dead or not) first i've removed the limiter resistance on non working side,
Then I cut the VSS line, Then CKV lines that enter to the panel one by one, trying to make the cut reversible.
The cut to VGH to supply the line entering in the panel with the 14v coming from a capacitor next to the cutted line.

Regards

[retrorepair2]

I've only blocked the right side clocks etc but then I get a blank screen. If I block none I get the result in the picture. This is with the VGH taped on the LVDS cable (there's no resistor on that board) and the signal jumped to the panel PCB test point as in the original post. In this case, anywhere from 1k to 100k works but I think the panel must have just now died

[Cornito]

You can't block clock signals on both sides otherwise you'll get vertical lines or black screen.
if both sides are defective now, there is no solution.

[retrorepair2]

This TV was working ok after taping it for about 6 months but started doing the boot loop again so I removed the tape and tried this out which worked but now get the attached.

Tried re-adding the tape (literally just blocked all control lines to the right side of the panel) but then get a completely blank screen.

Bit bummed out, is the panel just toast now? I've reseated the ribbons but same thing.

[Cornito]

Back on this topic to update.
tv lasted 2 months and then back to black screen.
I'll check in couple weeks if there is something wrong on DC to DC or of the second side of the panel is shorted now

[lotas]

Well, at least that's what it's like. You can also try...

[Cornito]

I've reduced the VGH voltage, to protect the panel only, the issue was on CKV.
The only thing that I could do I to check which one is the defective one. And rebuilding the others may help.
But I'm not sure that this will help the panel to stay alive for long time

[lotas]

You won’t be able to do it perfectly, since the CKVs on the non-working side don’t work, try restoring them, maybe the problem was only in the VGH.

[Cornito]

I've corrected my line that appeared some times by increasing a bit the VGH voltage, from 18.3 to 19V.
still having a red color issue on one side, red is more pink than red.

[Cornito]

I'll do the same, but now I may have a chance to keep it alive for some times.

I've redone all solders with better tin, smaller wires and I've added the dcdc step up.

It works, this has a bit corrected the red color. But now I have a small black line at the middle of the screen some times.

Please find attached the pictures of the job and a short video where we can see line appearing .

[nomoresonys]

Was just wondering about procedure, I try to stay away from samsung as much as possible.

[Cornito]

I've followed mostly the yt link posted in post#91.

Just used other videos on the same chanel to have more confidence on action to perform.
On one of his video he explained shortly how to tale the 14V on a cap close to the VGH line.

I'll need to improve some solder and place the DC to DC Step down, so i'll be able to take some pictures to show you.

Is there something that you would like to get in details?

regards

[nomoresonys]

Only link I see is post 91, can you post it here or the thread you found it in? Seems like you did the soldering in post 91 and something from another post, correct?

[Cornito]

Yep, the one linked in a previous post

[nomoresonys]

Interesting, did you see a video of this technique?

[Cornito]

Everything is done correctly and the TV works.
Have you used this one?

Model: MT3608
Input voltage: 2 - 24 V
Output voltage: 5 - 28 V
Output current: 0 - 2 A

Hello Iotas, nope I used nothing.
I've cutted the VGH line on the defective driver panel side and took the 14v from the caps just near and make the connection.

I've bought a DC to DC but the wrong one, step down don't work for me 'cause I guess the current consumption switch the main board DC dc into safe mode.

I'll buy a step up DC dc to take the incoming 12v and convert to 19V to preserve the panel.

[Diah]

Everything is done correctly and the TV works.
Have you used this one?

Model: MT3608
Input voltage: 2 - 24 V
Output voltage: 5 - 28 V
Output current: 0 - 2 A

i don't think this is the way...he did it with his brain way.... he wrote step up and he need to step down... so or so its just days to back for end... let him enjoy few hours

[lotas]

Everything is done correctly and the TV works.
Have you used this one?

Model: MT3608
Input voltage: 2 - 24 V
Output voltage: 5 - 28 V
Output current: 0 - 2 A

[Cornito]

Job is done, found a way a save it.
I'll add a step up DC dc to reduce VGH from 25 to 19v on whole panel.
Defective side has been reduced at 14v
Cuted ckv and grounded

[Cornito]

Using technics described into this videos i've been able to restart my TV:
https://youtu.be/kFINAT-Y204?feature=shared

Today i still face to some lines and bad colors, I need to reduce VGH voltages and rebuild some CK lines, but i'm moving forward.

I'll keep you up to date, i'll put a DC to DC to reduce the VGH voltages of the whole panel, just need to buy and receive these parts