Samsung UN55D6450 turns itself off and on endlessly, no blinks

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

I cannot. I can't tell if the heat is being wicked away but I do damage to the led long before anything comes loose. In fact nothing comes loose at all. I will try again later. But if that doesn't work I'll probably look at sawing into smaller working strips and replacing them that way.

Here's an edge on look

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Looks like ceramic substrate with metal core, and yet they still overheat. I'd use hot air, if available. Cover the LEDs you don't want to remove with foil to avoid damage. You usually don't care about preserving the dead LED.

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

I've tried hot air already. Seems to make the material covering the led itself come off easily once touched.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Hi Guys.

I'm facing the same issues with my UE40D8000 TV, it restarts ( but not endlessly ) for some minutes then it turns on, works for around 1-2 hours and then goes into restart endlessly. I'm thinking about something related to heat? here's a short video of the bootloop behavior: http://www.youtube.com/watch?v=AdYjrU_B7Jw.

Any ideas how to solve this?

Thank you!

[freakaftr8]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Hello Norberto.
Welcome to the forum. for best results I would start a new post instead of entering your problem into this post for best results.

As for your problem the first thing I would do is try to get a can of freeze spray and first try to cool the power supply and see if the TV comes back on When it is acting up. if that doesn't help it is time to take some voltage readings.

Hi Guys.

I'm facing the same issues with my UE40D8000 TV, it restarts ( but not endlessly ) for some minutes then it turns on, works for around 1-2 hours and then goes into restart endlessly. I'm thinking about something related to heat? here's a short video of the bootloop behavior: http://www.youtube.com/watch?v=AdYjrU_B7Jw.

Any ideas how to solve this?

Thank you!

[tibimakai]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

If it is firmware related, then most likely it's bricked and you need a new main board.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Thanks for the quick replies,

@freakaftr8, I was thinking that my issue is related to this one and didn't want to open useless new topics. Regarding the cooling, I'm not sure if it's needed, as if I leave the TV overnight and start it next day, it will behave the same way, bootloop for some minutes and then works 1-2 hours.

@tibimakai, How do I know if it's firmware related? I recently updated the firmware to version 1029. and after 1 day of working fine, the TV started too behave as described above. I tried factory reset, downgrade with samygo install 1025 again, all went succesfully, but TV behaves the same way..

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Looks like a bad main board - possibly BGA soldering failure. Also possibly a bad power board due to cold solder joints or other failures. It'd be best to open a separate thread for a different problem so we don't get mixed up.

[withalligators]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Yeah, not related to my/our issue. Mine could never start because it would endlessly try and get past a physically shorted LED (which it never could).

mmartell, how's it going with the LEDs?

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Got the led strip yesterday (thanks!) and had it all modded up but had some difficulty with figuring how to cleanly connect it to the panel. Still needs a little work. I only jumpered the one burnt led as I didn't have any luck removing any led's from my old board. Fired up great during a brief test run.

Will update with a pic once I get the strip mounted.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Hi Guys, back with news. Replaced my main, but unfortunately just noticed that the top of the screen is not lit, so I guess during the different testing so many reboots ( each one triggering the leds on and off ) burned the leds..., I'm pretty sure when the TV started to reboot, the screen was equally lit everywhere. Now with the new main the tv behaves slightly different, it doesn't turn on right after plugging to power, as it did with the my main, but it goes into standby and turns on only by pushing power button. I've tried with 2 different power boards and backlit is the same with both. Tried to disconnect the led's connectors, but still the same. Is there a way to test the leds?

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Unplug the cable between main board and power board and plug set in. Check the Samsung Fast Track supplement as additional jumpers may be necessary.

The tv powering on after power is applied is simply the main board remembering its last state. No worries.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

OK, here's how it look like. tried to take pictures in the dark to see the backlight, but the camera doesn't do quite well . But it-s clear that the top 1/4 is not lit. Here's a video too maybe it's better.

https://www.youtube.com/watch?v=OLWP328jrgM

According to this video ( ~ 14min ) , the tv has micro dimming technology meaning that each led can be independently turned on/off. I don't understand then why is such a long surface not lit, about 1/4 of the side edge, I can't believe so many leds burned out.

some questions ...

did you manage to replace the leds?
where did you find the replacements?
can be replaced on individual basis?
are these normal usual leds?

thanks.

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Find the Samsung Fast Track for this tv and isolate each led section with jumpers and verify the proper way whether you have bad leds before making the decision to go inside.

[tom66]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

It's not real micro dimming, it can just dim regions of the panel, in sections usually 1/2 or 1/4. This allows them to claim sky high contrast ratios which only work on certain specific scenes (such as a sunset, skyline, etc.)

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Yup IIRC this set does have 1/4 length dimming (25 leds) which jibes with what nroberto is seeing.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

I've checked the closest fast-track guide to my model, from Tom's site a UN46D8000, the only thing it mentions is :

Forced Backlight-On Mode:
1. Disconnect Power Cord
2. Disconnect wire harness from CN201
3. Re-Connect Power Cord
4. LED Backlight should immediately turn on

That's what I did when I took the pic and video from my last post. Noticed that the power cycling is the same even without the main connected, so the PSU has some kind of backlight check and restarts the PSU.
I saw the fast track for 55D6900 mentioned in this thread earlier, which is a bit more in details regarding the backlight activation. I guess it's not necessary to apply the jumper wire to those pins, although I do have the same PWM pins on my board.

Now we know the leds are gone. What's next?
how can I replace them?
can be replaced on individual basis ? or the 1/4 length or the full led stripe?

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

Full strip is easiest IF you can locate one.

Otherwise it is possible to replace single leds if you can find a strip to harvest them from. A bit more involved.

[nroberto13]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

thanks. do you happen to have pictures of the strip?

[mmartell]

Re: Samsung UN55D6450 turns itself off and on endlessly, no blinks

See here..

https://www.badcaps.net/forum/showpo...0&postcount=75