Samsung UE70TU7100 - flickering horizontal lines

[mrsith]

Hello again good souls.

Got an UE70TU7100. The TV starts up just fine, but right hand side of the screen is horizontal striped a bit, and there are some flickering horizontal lines on the whole length of the screen. I've seen similar static horizontal lines sometimes, when applying the cut tape method and covering wrong number of pins.

I've cleaned every connector with ipa, tried cut tape method on main LVDS ribbon as well as small ribbons, connecting the panel boards at the bottom. Tried squeezing the bezel and playing around COFs, but no reaction at all. COFs and panel boards don't appear hot in touch.

Any guides where to look for highly appreciated! Thanks!

https://streamable.com/vva038

[nomoresonys]

Re: Samsung UE70TU7100 - flickering horizontal lines

check the little mlc caps on the panel driver boards for shorts or very low ohms.

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Nothing shorted there, every single cap tested.

Maybe one of these resistors is bad? How can I comfortable test them?

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

i see no images of defect..

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

File hosters archive videos after 24h. Here's an active link:

CLICK

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

gate drivers fault, your only option is the masking tape method, post a **sun light** photo of the tcon, steady hand please..

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Unfortunately this unit doesn't have a separate t-con. LVDS tape goes straight from main board to the panel board.

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

If there aren't silkscreens (i think it), must use the dog penis method, at random...

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Love the naming. I was playing around quite a lot with the main LVDS tape, gonna try my luck with the small tapes interconnecting panel boards.

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

I have found an area on one of the small tapes, interconnecting the panel boards. I have been looking at the side that's striped, obviously. The area, if covered, causes the flickering lines to disappear completely, but the picture is still not perfect - something is definitely off with red colour. I have managed to isolate the issue to one particular pin (see photos - Netflix logo on good side of the screen, Youtube at the bad one).

EDIT: It's not visible very well on photos - red colour seems to be saturated very little, almost grayed out, and striped/dotted a little. Difficult to describe this, the picture with the white Youtube icon seems the most accurate.

The overall effect is far better than flickering lines present previously, but that's still not it. What can I do now? I've been reading about cutting signals instead of blocking them - i.e. cutting ckv1 and ckvb1 and strapping them together - what's the actual difference? Worth giving it a shot here?

Again, many many thanks for your time and effort guys!

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

no need of cutting lines, that is made when tcon is integrated with panel, try locating on the panel small boards the testpoints related to clock signals, i.e. CKVxxx, then with multimeter you locate the corrispondence on the input connector, the you mask one CKV at a time..

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Should I keep that shown above pin covered when doing this?

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

remove it

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Covering any single pin did not resolve the issue. Tried covering them one by one, all of them, in pairs, random amounts in random combinations. Was getting various results, the best of which was a perfect picture showing every ~5 sec for around 1 second, then getting striped again etc.

I suppose there's not a slightest chance that the issue is actually produced on the other side of panel, which looks fine?

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

If the panel has got side tabs must be removed on the side where the lines and bands starts..

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Unfortunately this panel has no side tabs at all. Is there any hope left?

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

sorry, i forgot to mention, if you have an oscilloscope you can trace the clock lines from the main board, so you can mask them, better to mask only those requested.. clocks are about 22khz for a normal full hd resolution, those lower like 100hz are starting signals, if you mask those, there is one per side, it's equal to mask all clocks

[mrsith]

Re: Samsung UE70TU7100 - flickering horizontal lines

Regular multimeter was just enough to find ckv pins.

[Davi.p]

Re: Samsung UE70TU7100 - flickering horizontal lines

with frequency meter...?

[alfatv]

Re: Samsung UE70TU7100 - flickering horizontal lines

I have found an area on one of the small tapes, interconnecting the panel boards. I have been looking at the side that's striped, obviously. The area, if covered, causes the flickering lines to disappear completely, but the picture is still not perfect - something is definitely off with red colour. I have managed to isolate the issue to one particular pin (see photos - Netflix logo on good side of the screen, Youtube at the bad one).

EDIT: It's not visible very well on photos - red colour seems to be saturated very little, almost grayed out, and striped/dotted a little. Difficult to describe this, the picture with the white Youtube icon seems the most accurate.

You get this effect when you block VGH