Samsung UN50KU6300F constant reboot, bad backlights?

[x_orange90_x]

This TV is in a constant reboot where the screen very dimly lights up for about 2 seconds and says SMART TV. I checked the power supply and visually all components look good. I unplugged the main board to see if the backlights would come on but they do not. I also tried my LED tester on the backlight plug and didn't get anything. I know some Samsungs will not light off a single led is out regardless of using a tester, so I'm thinking they are bad. I found a whole set for about $25 which isn't bad, but before I buy them is like to know if they would indeed cause a constant reboot like this tv is experiencing.

Attached is a short clip of it doing what it does.

[x_orange90_x]

Here's the clip

[diif]

"The screen very dimly lights" suggests the LEDs are working.

[nomoresonys]

Probably failing backlights, maybe unplug backlight cable and cable from powerboard to mainboard, plug power cord in and check the output dcv at backlight connector.

[x_orange90_x]

"The screen very dimly lights" suggests the LEDs are working.

We're you able to view the video? They just blink on for like a second or 2. They don't stay on. The whole cycle is just a couple seconds long with the constant reboot and flash.

Probably failing backlights, maybe unplug backlight cable and cable from powerboard to mainboard, plug power cord in and check the output dcv at backlight connector.

I will try this. With them unplugged there should be steady voltage on the plug right? I had a similar issue a long time back, also with a Samsung, where the connectors between two LEDs strips was arcing, causing a constant flashing of the backlight. I don't recall there being anything visible on screen though, but that model may not have had a logo screen.

[nomoresonys]

Your led tester not doing anything is a pretty good clue that it's probably bad led/s in backlights.

[nomoresonys]

Just need to treat the panel like a baby, they are flimsy and fragile but fortunately it's 50 inches and not bigger, check some youtube videos on backlight replacement for procedure clues.

[diif]

We're you able to view the video? They just blink on for like a second or 2. They don't stay on. The whole cycle is just a couple seconds long with the constant reboot and flash.

If you say they light for 2 seconds, then they work up to a point. Enough to test with a tester anyway i would think. I should have been clearer with my earlier reply.

Most times the damage happens on reassembly, the LCD is laid in the plastic guides and as the front metal bezel is clipped back on the LCD jumps out of its place and gets cracked when the metal bezel is pushed on.
Also damage to the flex cables to the buffer boards. Use painters tape (it leaves no residue) to hold them out of the way.
It's best to wear gloves to avoid finger prints.

[x_orange90_x]

I have replaced them on a few sets before including a 60". Normally I don't have any issues. It's when they do something stupid like put tape of side COFs that things don't go well. Yes, that happened with a TCL before... Went to remove the tape and it peeled the tap right off the panel 🙄

[x_orange90_x]

I just ordered backlights. $25 total shipped, not bad. I'll update when I've got them in.

[handsworth]

Before you take screen out, unplug cable from power supply and main board. Power up and see if lights come on and stay lit. Your leds may be good. I have been thru many Samsung KU, JU and TU models. Its a bad panel that mostly causes this constant reboot.

[x_orange90_x]

Before you take screen out, unplug cable from power supply and main board. Power up and see if lights come on and stay lit. Your leds may be good. I have been thru many Samsung KU, JU and TU models. Its a bad panel that mostly causes this constant reboot.

That's the first thing I did. No lights came on. Then I tried with my backlight tester and they still wouldn't light. Thanks for the tip tho, I appreciate it!

I'll test the strips individually before removing them though.

[x_orange90_x]

I got the backlights today. Took it apart and put them in only to find out I ordered the wrong ones. There's two different versions and I had to guess without having already taken it apart. So naturally I pick the wrong ones. They physically fit the chassis fine, but the reflector sheet doesn't line up with the leds because they are offset for some stupid reason in the other "version".

Should I definitely try and return them for the correct ones? Or could I successfully modify the sheet without ruining picture quality? Any one ever do this?

[nomoresonys]

If you say they light for 2 seconds, then they work up to a point. Enough to test with a tester anyway i would think. I should have been clearer with my earlier reply.

Most times the damage happens on reassembly, the LCD is laid in the plastic guides and as the front metal bezel is clipped back on the LCD jumps out of its place and gets cracked when the metal bezel is pushed on.
Also damage to the flex cables to the buffer boards. Use painters tape (it leaves no residue) to hold them out of the way.
It's best to wear gloves to avoid finger prints.

First post, he already tested with a backlight tester.

[x_orange90_x]

First post, he already tested with a backlight tester.

I also tested each strip before removing them and found 3 bad LEDs.

When I put all of the new ones in and plugged in the tv (with main board disconnected) I still did not get backlights. I'm thinking this may be a model that does not function this way. Obviously if there were 3 bad LEDs that would be an issue, so I'm hoping that's the ONLY issue.

I ordered the correct strips. Hopefully I can return the others.

[nomoresonys]

Indeed, just clarifying, apparently dif thought they were fine.

[x_orange90_x]

I got the correct strips and put it together and it won't power on.. the indicator light just flashes red and so does the optical port. I tried a spare main board that fit and get the same result.

[x_orange90_x]

I should mention that even after replacing the backlights they still do not light up when the main board is unplugged from the power supply. I'm suspecting a power supply issue, but I have also read about bad panels causing the standby light to flash. I should still get backlights with the main unplugged right? Because that's eliminating the screen as well.

I have a main board and power supply out of a 55" that is *almost* compatible with this tv. The main board looks nearly identical and all the ports and connectors are the same. The power supply boards differ though where the led plug is concerned. They do not have the same size plug, therefore I cannot connect the backlights to the donor board.

I'm thinking of putting the donor power supply in and trying with the LEDs disconnected. I *should* get the tv boot without them plugged in, correct?

I've attached pictures of the original and spare boards, as well as a pic of the led plug that is different between the two power supplies

[vinceroger69]

yes should get backlights without mainboard connected, certainly sounds like a power supply issue

[x_orange90_x]

yes should get backlights without mainboard connected, certainly sounds like a power supply issue

If I connect the spare power supply to the main and leave the backlight disconnected, should the tv boot up? I would expect it would, just as if backlights were shorted.