Samsung UN50KU6300F constant reboot, bad backlights?

[nomoresonys]

Yep, that's a bad one, maybe switch m both out for good measure.

[x_orange90_x]

I removed one leg of each of those two diodes from the board and checked them. D9002C checks good, but D9001C reads .298 both directions.

[x_orange90_x]

Did you check all the diodes on top of the board.

I actually was just searching the forums with the board model number BN44-00807A and someone said to check two diodes because one of theirs was shorted. I will remove and test those two tonight.

https://www.badcaps.net/forum/troubl...78#post1751678

I seen in another post there's also a diode on the bottom that fails on some people:

https://www.badcaps.net/forum/troubl...-fix#post80203

[nomoresonys]

Did you check all the diodes on top of the board.

[x_orange90_x]

not sure as the tv maybe detecting a fault with backlights disconnected, there was a thread the otherday where the op was having no backlight isssue turned out it was a bad solder joint so check the psu for cracked joints etc

I tried with the spare power supply and the tv boots up. I can see an image with a flash light. So that confirms the power supply is at fault. What should I be looking for on it? Nothing appears to be burnt, leaking, or swollen.

I did a quick voltage check on the plug to the main board and I have 5v standby. The other ones such as 13v and PS_ON fluctuate all over the place.

[x_orange90_x]

not sure as the tv maybe detecting a fault with backlights disconnected, there was a thread the otherday where the op was having no backlight isssue turned out it was a bad solder joint so check the psu for cracked joints etc

I'm going to give it a try. At the very least I should get a different blink pattern on the standby light.

[vinceroger69]

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.

not sure as the tv maybe detecting a fault with backlights disconnected, there was a thread the otherday where the op was having no backlight isssue turned out it was a bad solder joint so check the psu for cracked joints etc

[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.

[vinceroger69]

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

[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

[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.

[nomoresonys]

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

[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]

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]

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?

[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.

[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]

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

[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 🙄

[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.