Samsung GU58TU7199 reboot loop

[kevin_allein]

Hi, I have two identical Samsung GU58TU7199, which both had the reboot loop. On that model TCON is integrated into the motherboard and there is only one FPC cable, which goes to a driver board driving half of the panel (left side seen from the rear of the TV) and than another FPC cable connecting left side to the right side.

The first one was easy, once I disconnected the FPC between left and right the TV did start up. I soldered a bridge on the motherboard on the test points as found here in the forum or on Youtube and half of the screen was coming up. I than tried the CK1..8 lines on the right side and had to cut 4 of the 8 lines to get the TV up and get an image. Unfortunately there are horizontal lines visible on the screen, I guess there is nothing else I can do ?

The 2nd unit behaves strange. When I disconnect the FPC between left and right the TV starts and I hear the chime. However when I create the bridge between the test points, it goes into the reboot loop again, so I can never see any image. Without that bridge, all the panel voltages (VGH, VSS, LC1, LC2, ...) and clocks seem to carry no signal, so nothing to debug. I have also tried swapping the motherboards, as I have two identical units, but that did not help. So there must be something else on the left / main panel driver board.
Any idea what to do here ?

Thanks in advance for any tips

[Davi.p]

ok there is a fault on left, but why don't you started masking lines on that side? this is by cutting lines or putting pull down resistors on the strip board

[Diah]

samsuns with panel issue usually there are ESD diode pack on the right side close to the end of the panel buffer boards... remove the one shorted you will have full image with out any line... so show us the right side of the puffer boards to see if there ESD diode installed on it.

[kevin_allein]

For the two responses:
- I removed the ESD protection diodes on the right side on both TVs. I still had to cut 4 CK lines (CK1, CK6, CK7 and CK8) in my case. TV would go into reboot loop if any of those was connected. So I do not understand, how I can improve the missing horizontal line now ?
- with just the left connected and the FPC between left and right removed, the TV does not reboot. It will only do that, once I connect the bridge on the motherboard. So will cutting the same lines help me ? You write: "putting pull does resistors on the strip board". I don't understand this. Could you please explain ?

[Davi.p]

if you know the value of the resistor you can draw the signal to ground with a resistor, flying resistor+ wire to avoid cutting traces..

[kevin_allein]

Davi.p but if I draw that signal to GND, that seems to be the same as the current situation, where a signal is shorted to GND inside the panel ? Am I missing something here ?

[kevin_allein]

Does noone has a Tip, why the bridging of the motherboard does not work in my case ?

[Davi.p]

the bridge tells the tcon.section.that the panel is connected but the protections are still active , you have to exclude some clock lines or use the short killer method

[kevin_allein]

I thought since the TV was not in a reboot loop without the bridge, that I would have different problems.
What is the "short killer method" ?

[kevin_allein]

I did some further experiment and that confuses me now completely. With the bridge between left and right panel driver board removed, I cut VSS. I found a video on Youtube, that stated, that VSS actually should be cut not at the ESD protection device, but on the very left side of the panel.
After doing that, the TV started with the bridge on the motherboard. So half of the screen showed a picture, but just strange lines, not a normal picture.
I wanted to try, whether now the other side would at least show something as well and connected the ribbon cable between left and right panel driver board. Now the TV would not start again.
I removed the ribbon cable again and now the TV is always in reboot loop, despite VSS disconnected. For a test I also cut VGH, but still the same result.

I am totally confused now, why did it power up once and now things are worse than before.

https://www.youtube.com/watch?v=kFINAT-Y204

[Davi.p]

to answer post 9, this is because removing half the panel connections disables the panel so no fault error happens to the tcon circuitry, by making the jumper wire you trick the MaBo to enable the panel again, the tcon detects panel error and software hangs..

cutting vss i don't know which sense has, i suggest to cut vcc1.8v if present, switching tv on off many times and then joining back 1.8v line, this trick worked for me once a time
.