Samsung UE40D8000 bootloop ( powerloop )

[nroberto13]

Hi Guys.

I'm facing the power on / power off issues with my UE40D8000 TV.
When I plug it to power source it starts itself without pushing any button either on remote ro the TV itself. The power led turns on, Samsung SMARTTV logo shows up on the screen and then the TV shuts itself off ( I can hear a click, most likely from relay ) and the process starts over and over again. After 4-5 minutes of this bootloop it turns on, works for around 1-2 hours and then goes into restart endlessly.
Could it be something related to heat? maybe a faulty component?
here's a short video of the bootloop behavior: http://www.youtube.com/watch?v=AdYjrU_B7Jw.

I did a firmware update ( 1029 ) one day before this behavior kicked off, the TV worked fine for 1 day and then the show ...

I downgraded the firmware with samygo, installed the old 1025.1 but still the same.

Any clues how to determine the faulty part?

AFAIK the TV is running Linux. Would it be of any help if I could make a console connection to it?

Thank you!

[johnboy1313]

Re: Samsung UE40D8000 bootloop ( powerloop )

I would take the back off and use a hairdryer to warm the main board or the power supply up to see if you can get it to start sooner than what you've been dealing with. Once you know which board, try focusing on specific areas of the board.

[RJARRRPCGP]

Re: Samsung UE40D8000 bootloop ( powerloop )

I wouldn't be surprised if it requires a reflow!

Sounds like something my Uniden Bearcat scanner would do until I reflowed the DC input connectors on the PCB.

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

OK, tried to heat the boards but actually found another solution. I observed that turning the TV around it's leg sometimes solve the issue. I think I found a position now in which the TV is working fine. I tend to believe it's definitely a connection issue, the question is again, on which board ..., any clues how to track it down?

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

The position is not working anymore....
When I disconnect the T-CON board, the reboots are coming on a randomly and mostly I can hear the sound for some seconds or minutes then a reboot comes, and so on. Does this mean anything, if the T-CON board is the issue or that's not the issue? thanks.

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

I took the TV to a service center and they confirmed the PSU is faulty. I think this is the happiest case because can be repaired by replacing components on it. Would somebody guide me how to find the faulty components please?

[tom66]

Re: Samsung UE40D8000 bootloop ( powerloop )

I would not immediately agree with the service center's conclusion, they could be wrong. But, if you want, you can try heating parts of the power board up - simulating that warming up the TV would normally do - and see what happens. Maybe it'll show it actually is the fault but I suspect it's a main board problem.

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

thanks tom66, but the thing is that lately the TV doesn't start at all, neither after the warm up. I tried to heat up the PSU but didn't start. Now it's just rebooting forever.

[tom66]

Re: Samsung UE40D8000 bootloop ( powerloop )

That sucks. Another dead Samsung D series main board. Surprised panel hasn't died to be honest. It is crazy. So many of these dying...

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

is it definitely the main board? only way to replace it?

[tom66]

Re: Samsung UE40D8000 bootloop ( powerloop )

Not definitely, but the symptoms match a lot of other TVs on here (mostly C and D series) which have been bootlooping. Bad main boards. Replacement is guaranteed to fix it; some people have had luck with reflowing them, but they don't always last.

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

any way to check if PSU is faulty or not? maybe some voltage checks ... or a service manual? thanks.

[selldoor]

Re: Samsung UE40D8000 bootloop ( powerloop )

You can always test the voltages on the pins in the connector to the main board. but unless it says on the board what they should be its just a guestimate as to whether they are correct. Important thing to look for might be a voltage change on a pin as it cycles on/off. Common values to look for are 3.3v 5v 12v 24v

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

ok, just got my new PSU, and TV behaves the same way. So most likely the mainboard is faulty. How could I reflow the mainboard?

[Kilroys]

Re: Samsung UE40D8000 bootloop ( powerloop )

Just a guess

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

many thanks for the advice. I already tried to turn off everything wireless in the house, and didn't helped. As a side note, when the TV started after some reboots I was able to access the service menu, and remember that wd count was 0, so it wasn't rebooted by watchdog, I guess.

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

Just changed the mainboard with one from a 55d7000, but doesn't work. with this board the display doesn't light at all, it doesn't show the samsung smart tv logo either. the model and code is the same on both boards : bn41-01622C. could it be due to the difference in the tv model? mine is 40d8000 and the replacement one is from a 55d7000.

[mmartell]

Re: Samsung UE40D8000 bootloop ( powerloop )

The board is the same fo 7000 series and the 8000 series ? Hmmm.. Still I would expect the revs to be different. So the tv turns on and stays on just no pic ? What about sound ?

[nroberto13]

Re: Samsung UE40D8000 bootloop ( powerloop )

no sound. I'm not quite sure if there are any differences between series 7 and 8 from tech specs point of view ... maybe only design.

[tom66]

Re: Samsung UE40D8000 bootloop ( powerloop )

the 8000 might use a different panel...