Samsung UE65KS9000 lines and reboot loop

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Should it give me different readings when switching probes then?

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

It doesn't look like a cap, see last photo in my previous post.

Took all 3 ESD diodes out and measured the pads, still all 9 of them shorted to ground.

COF short

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Any possibility at all to find out which COF exactly? My friend has ordered a COF machine so I could take the TV to his workshop to try and sort it....what would be next steps to fix or bypass the problem?

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

follow the short point u got before and go where the line on screen.. you can trce it on the panel glass as the cof ribbon will not cover all pins on glass

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Unfortunately the lines show on the whole width of the panel, they just start by being short and become longer and more visible every reboot or so. Not really possible to find at which point of the screen they appear (possible to say on what height it starts, but not width as it's all over). I cannot see any traces going from shorted pads either.

Is there any way I can confirm the COF short? Or are there any other possibilities at all? Tough diagnosis to accept

[nomoresonys]

Re: Samsung UE65KS9000 lines and reboot loop

might be able to bypass it, there's one of many videos, you might even find one in English but it might take some looking, why youtube doesn't have a choice to search for a preferred language is a mystery: https://www.youtube.com/watch?v=wQA02AvViRE

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

yours photo... can you upload one for complete cof ribbon include the buffer boards

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Pics attached with this particular ribbon next to the shorted spot.

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

i don't like the look of the end left & right cof ribbon specialty the right end.. its look like it had suffered from short of the COF. if you have microscope you can exam it because the first line are GND of the boards where the ESD GND side go same for left side first line GND of boards... yours ESD out side the boards if there no short to them put them back... and if this cof where the line.. take it out and wait to yours friend machine arrived to do it... but i have doubt it will worth.. as i mentioned before post #9 this panel are scrap and cheat from SAMI

BY the way... you have short messurment even the LVDS disconnect right !

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Right side of that ribbon looks tiny bit different because of hot air used to take ESD diode out. Surprised you've noticed that, good eye. I examined it closely and it seems totally okay. It surely was before desoldering at least.

This resistor/diode thing I've been asking about in #36 - if it indeed is a resistor, shouldn't it have constant resistance? And shouldn't the resistance be the same regardless of probe switching? I know this may sound silly, but the fault is getting worse with the set warming up, and this resistance getting higher with time seems a bit related. At least I hope it is, everything would be better than fighting with COFs....

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

take it out.. as its one pin go to GND where short point of ESD share with
but dont lost it LOL

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Just seen your edit from post 49...yes, I even disconnected the U-shaped ribbon connecting two buffer boards. The resistor/diode thing that I asked about in my previous post is on the other board. I mean, there are 4 buffer boards in total. The SMD is on the same side as 3 shorted diodes, but not on the same physical board, they were connected by the U-shaped ribbon. If I'm still reading short with that ribbon disconnected, I suppose I should be only looking at this particular board....
Are these diodes/pads 100% definitely shorted? I mean, is there any logical way in which these pads SHOULD be shorted to ground?

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

my questions was if the lvds between MB and panel disconnected while you trace the short on panel?
in general any check on panel all lvds must disconnected.

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

yes, the motherboard isn't even attached to the tv at the moment. I remembered that lesson during fighting with Philipses recently

Just out of curiosity - is it still ok to have lvds tapes plugged into panel but not into mainboard? I had them disconnected both ends but still better to know for future.

[Diah]

Re: Samsung UE65KS9000 lines and reboot loop

yes, the motherboard isn't even attached to the tv at the moment. I remembered that lesson during fighting with Philipses recently

Just out of curiosity - is it still ok to have lvds tapes plugged into panel but not into mainboard? I had them disconnected both ends but still better to know for future.

only in case you are sure all LVDS gold pins are fine and nothings move aside ( make short ) or broken. my ways always to keep boards / panel SOLO. to avoid any miss from third party

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Makes sense.

Would a bad resistor, that reads for example 0.2ohm instad of couple of Kohms, possibly cause short reading on esd diodes?

[mrsith]

Re: Samsung UE65KS9000 lines and reboot loop

Hi again folks. I'm clearing my workshop so getting rid of old unrepaired stuff. Had a success with taping 70" Samsung recently, so got extra motivation to get back to this one.

1st of all, I've soldered back the ESD diodes. Checked if the bottom pins aren't shorted with DMM. Top pins are all gnd anyway so didn't check them for shorts.

Tried turning the TV on - it started but I had no picture at all, just backlight. It did reboot after a while so it looked like everything is as it was, and thought I must have had connected something wrong. Reseated all the ribbons - and the TV doesn't want to start anymore. Tried playing around with ribbons and cables - the backlight still goes on when MB disconnected. I am getting the red standby diode, it does blink when I press the power button, but that's it.

Main board and PSU were both OK, and the TV started twice for a minute before reseating the ribbons. What could I possibly screw up this time? I've tried playing with ribbons, disconnecting them, taping part of them over etc - but can't get the TV so start again, even without picture.

Honestly - is there any point in playing with this TV anymore or should I cut my losses and strip it for parts? Hate doing that when the LCD isn't broken but there's no point in keeping dead TV.