samsung un65nu6900f common problem, digging deeper

[ggil44]

Hi xfox, glad to see you found a work a round. I too have had no luck with changing R13246 values. The only "fix" I had was to tape pins 13 to 24 on the Right (shorter) ribbon cable which results in a color fade from Left to Right on the TV screen. Could you show a picture of what is under the blue masking tape by the ribbon cable and identify what pins or points you soldered the wires from the 2 second delay circuit from the 5V power source? Did this give you a normally working TV with no color fade? Thank you.

[xfox]

Somehow I UI of this TV is very slow, do you guys have a same feeling?

[nomoresonys]

Very nice work, good to see this method works sometimes when the resistor change does not, glad people are finding ways to get more use from these tvs. And SHAME on samsung for these design flaws.

[xfox]

Ok, finally got my delay switch, installed, took power 5v from USB on board, delay is set to ab 2 sec, TV is working as expected, thank you everybody for your help and ideas, maybe this one would be useful for someone else.

[JGMusic74]

I had the same results as many with the tape method. I was able to pinpoint a single pin and insulate it with tape to stop the boot loop but had major color fade on the left side of the screen. After finding this thread, I fixed the TV completely by replacing r13246 on main board 10ohm resistor with 15k with previously applied tape removed. We've been using the tv daily since Xmas and it's perfection. 🙏

[ggil44]

Hello xfox, I have the same problem with the same TV (UN70NU6900FXZA). I found that if I tape pins 13 - 24 on the Right ribbon cable (shorter one) that I can eliminate the boot loop but I get the dreaded color fade from left to right with the picture otherwise, the TV works normally.

[JGMusic74]

I am so grateful to have found this thread! Having repaired several other LCD TVs over the past several years, usually due to failed power supply capacitors, I thought I’d take a stab at this 2020 70” Samsung my neighbor put on the curb. The boot loop issue was misdiagnosed by an online tech as a bad main board. I swapped the main board and the issue remained. Fortunately I only paid $52 for it so I wasn’t out much. Thanks to this thread I was ultimately able to repair the TV by replacing the R13246 with a 15k I happened to have in my stash. I had previously isolated a single pin on one ribbon cable and the TV worked but the color saturation was degraded on the left half of the screen. With the tape removed from the pin and the resistor swapped out it is now perfect and we’ve been watching it for the last several hours with no issues. Thank you!

[xfox]

tried resistance from 1Mo to 0, no luck

[itelite]

That very much sounds like this is the same problem then (if indeed we are talking about putting a wire between the VGH resistor pads or equivalent.)

Im sure you thought of this, but if not, keep your wire as is, and use it to test the various resistor values. That way you don't need to solder anything each time. I think it is just going to be a matter of finding the correct value. Start with a high value and note results. Again, as I'm sure you know, resistors in series will add, and in parallel will divide.

Couldn't hurt to verify resistance with a meter as well.

[xfox]

so with one of described pins disconnected power-on then 3 sec wait then connect wire, tv starts with perfect picture, was working for whole day no issues, will try 1Mo resistance yesterday, and delay switch ordered, probably would take few weeks to come. I could not find any shorts tried tape method on all pins, only those I described prevent power cycling

[itelite]

I tried that, works as expected, tried resistance from 0-50Kohm, do you think it may need some higher resistance?

When you say "works as expected" do you mean successful, or unsuccessful?

If successful with no color or image artifacts, I would call that a win.

Otherwise

I suppose a decent test would be no resistor at all. That would be equivalent to taping over the VGH pin (or an infinite resistor). If that works (if memory serves, you should get the boot up chime, but no image, but I could be wrong on that. then you know the problem must be on the VGH circuit, at that point I would try a very high resistance like 1Mo. then keep cutting that resistance in half until something interesting happens. Thats why I've been using a potentiometer for testing.

[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

[xfox]

I tried that, works as expected, tried resistance from 0-50Kohm, do you think it may need some higher resistance?

[itelite]

I just got one of these 65 inch that is, the main board is slightly different as those resistors arent present, anyone found a fix for the actual model in the post? Same reboot. Thx

Try to find the VGH pin, and work from there. It should be very similar.

[itelite]

My feeling is that you must be doing the mod incorrectly. Everything you are describing suggests that you are having the same problem with the same equipment. Post some high quality pictures of your work. See if we can sort out where it's going wrong. Ive done quite a few of these, and this always works with various resistance values.

Something I've found to be helpful is to use a potentiometer in place of the resistor, that way you can adjust the resistance to see where it boots properly and where is doesn't. Note the results, and you have your tolerance window.

Maybe yours has a smaller tolerance window, but that would be my last place to look.

Beyond that, if you want to try your delay thing, simulate it first with a wire. Connect a wire to the correct points, snip the wire in half and strip the insulation. Turn tv on, count to 5, put the wire back together. Observe results.

[xfox]

Tried everything... And I got one idea... what if I'll put some delay switch like this https://www.aliexpress.us/item/32568...100001074166_4

[EazyBone]

I just got one of these 65 inch that is, the main board is slightly different as those resistors arent present, anyone found a fix for the actual model in the post? Same reboot. Thx

[xfox]

Btw, I have no ground on pin 2

[nomoresonys]

Interesting, my memory is bad, hopefully a member who has been diving deep on these address boards and pin masking can help, sometimes the short can not be "fixed" with taping.

[xfox]

Just tried, was not able to get a picture but if I cover one of pins, TV is not restarting so if you look at main board top ribbon (right on LCD) second or one before last, and on lower ribbon (left on LCD) first and last, covering any of those pins will get tv of power cycling but there is no picture.