Samsung UN55MU6103F video problem; has colored stripes on the display

[alro7779]

Hello, everyone!

A co-worker gave me a 55-inch Samsung TV model UN55MU6103F so I can try to fix the following problem... As soon as I plug it in to the wall, the TV turns on, and the display shows a few stripes all over the screen. I took off the back cover and disconnected both ribbon cables that go to the display (one at a time) so by doing that I can narrow down the bad section of the problem, but in both cases the display turns black. I know there are some voltages that I have to check (VGH, VGL, etc.) but don't know what reading each has to show. If anyone could guide me on this, please, I'd really appreciate it.

Thanks in advance!
Alex.

[nomoresonys]

Maybe try the self diagnoses, might give a clue: Home>Settings>Support > Self Diagnosis > Start Picture Test or Start Sound Test.

[lotas]

I took off the back cover and disconnected both ribbon cables that go to the display (one at a time) so by doing that I can narrow down the bad section of the problem, but in both cases the display turns black.

This is because you need to install a feedback jumper on the motherboard between points FB_TRDY_1 and FB_TRDY_3.

[alro7779]

Maybe try the self diagnoses, might give a clue: Home>Settings>Support > Self Diagnosis > Start Picture Test or Start Sound Test.

I did that, and this was the result:

Thanks for your response!

[alro7779]

This is because you need to install a feedback jumper on the motherboard between points FB_TRDY_1 and FB_TRDY_3.

So, if I do that the display won't turn black after disconnecting the ribbon cables? I'll look for those points you just mentioned. I'm just a beginner in all the TV repairing world, though; I wanna learn more. Thanks in advance!

[lotas]

So, if I do that the display won't turn black after disconnecting the ribbon cables? I'll look for those points you just mentioned. I'm just a beginner in all the TV repairing world, though; I wanna learn more. Thanks in advance!

Yes, here's a hint.

[alro7779]

Yes, here's a hint.

I can do that. Thanks for the hint. However, I'd like to know what exactly that jumper does to the circuit (trying to understand and learn).

[lotas]

I can do that. Thanks for the hint. However, I'd like to know what exactly that jumper does to the circuit (trying to understand and learn).

Samsung has this protection: when you disconnect even one cable, the feedback between the T-CON and the panel is lost, and the T-CON blocks all voltages for powering the panel. By installing a jumper, the supply voltage to the panel will be constantly present even if one or two cables are removed.

[alro7779]

Samsung has this protection: when you disconnect even one cable, the feedback between the T-CON and the panel is lost, and the T-CON blocks all voltages for powering the panel. By installing a jumper, the supply voltage to the panel will be constantly present even if one or two cables are removed.

Oh, I see. Thanks for this information, man. How did you learn all this stuff?

[alro7779]

Yes, here's a hint.

I did the jumper, I disconnected both display ribbon cables (left first and right second), and the pictures show the result: