Trying To Fix: Samsung UN50TU7000 - Weird Fading Screen then Red blinking light

[KYBOSH]

Picked this up to resurrect.
When I plugged it in it comes on for about 1 minute... after a minute the screen blacks out and I gets blinking red lights on the power button.
I read that a common issue with this model is a failed BGA so I ordered a replacement on eBay.

Sometimes the TV would produce an expanding blob on the screen before going black.
See Video here


20240916_211200_1.mp4

I ordered a replacement board off of eBay and installed it tonight and got the same behavior.

Did I get another defective board or is there an issue with the panel?

After unplugging the TV for about 2-3 minutes the TV comes back on again for a while only to do the same thing again.


Thanks for the assist.

[EazyBone]

I have had 4 of these tvs, every one was a panel short.

Sounds like the panel if it does it with new boards also. I don't feel a board would do that.

[KYBOSH]

I have had 4 of these tvs, every one was a panel short.

Sounds like the panel if it does it with new boards also. I don't feel a board would do that.

Thank you EzB. I have always known a panels to have hard shorts. Either it was shorted or it wasn't.
This is the first time of me seeing a screen do this. And what makes things more mysterious is the 'short' goes away (at least for a while) after you unplug and reconnect the TV from the mains.
Could this really be a dying capacitor or resistor on the panel boards?

Edit to add:
The replacement board was used as well so I couldn't immediately rule it out.

[EazyBone]

I honestly don't know. When it comes to small tvs the time I invest is very small. Maybe more advanced people here could tell you, I'm basically a novice that can get around with common problems.. but I'm 0/4 on these 50 inch samsungs and they either had lines that turned into rebooting or some version of that.. so that's all I'm going off of. I just can't see two boards doing the same weird ass thing.. I see more every day but shit who knows.

Ands it's specifically the 50 inches, I have 55s and 65s etc etc and I've repaired them but 50 is no go.

[nomoresonys]

can you post a picture of the screen "blob"?

[KYBOSH]

can you post a picture of the screen "blob"?

As requested.
The picture doesn't do it justice.
If you are able to see the video you'll see how it appears like an ever expanding blog of ink and then the screen goes to black.

[EazyBone]

It's better to post videos from YouTube Link. People don't want to download your files is why he is asking for pictures. Viruses do still exist. At least I think that's why.

[nomoresonys]

Notorious problem with MANY MANY samsungs. Some have been able to recover with resets, but in probably most cases for a short time before it comes back, I try the simple one first, unplug tv, hold power button on tv down for 30 seconds, wait 5 minutes and retry. Can also try different forms where you leave it unplugged for a day or 12 hours or 6, and also some were successful with factory resets. On some of my old lcd tvs in the past I would get similar rolling blobs of black and it was due to the tab bonds becoming loose, which I made workable again with shims or tape which was easier with the old tvs because they had a nice big metal frame to work with. Not sure if it would work as well if at all with the newer tvs tho.

[nomoresonys]

Here's an example of the tab bond issue I referred to: https://www.youtube.com/watch?v=vCExlSnG4yY

[EazyBone]

That videos awesome. Had no clue about that. OP I'd be curious to see if this does anything for you. Learning something new. Thx sony

[Davi.p]

Kybosh, you are talking about changing board and failing BGA without naming it, more than this are missing photos of the boards, at least main and tcon if any, a very simillar defect is due to bad mosfets in tcon power section but more probably bad ceramic cap in recent sets

[Diah]

this is disorder at the gate transistor in panel ..the reason are MB panel driver.. try hard reset from service menu... or upgrade the firmware then again hard reset from S.M

[nomoresonys]

this is disorder at the gate transistor in panel ..the reason are MB panel driver.. try hard reset from service menu... or upgrade the firmware then again hard reset from S.M

+1, sounds like a winner, try that.

[CapLeaker]

this is disorder at the gate transistor in panel ..the reason are MB panel driver.. try hard reset from service menu... or upgrade the firmware then again hard reset from S.M

Agree with that too! It's not the main board's fault.

[KYBOSH]

Kybosh, you are talking about changing board and failing BGA without naming it, more than this are missing photos of the boards, at least main and tcon if any, a very simillar defect is due to bad mosfets in tcon power section but more probably bad ceramic cap in recent sets

Sincerest apologies Davi. I forgot the forst rule of badcap club!

[KYBOSH]

this is disorder at the gate transistor in panel ..the reason are MB panel driver.. try hard reset from service menu... or upgrade the firmware then again hard reset from S.M

Thank you for this Diah. Problem with this soln is the screen would not stay on long enough to navigate thru the service menu to reset it right? Ive never been done it before.

[KYBOSH]

Notorious problem with MANY MANY samsungs. Some have been able to recover with resets, but in probably most cases for a short time before it comes back, I try the simple one first, unplug tv, hold power button on tv down for 30 seconds, wait 5 minutes and retry. Can also try different forms where you leave it unplugged for a day or 12 hours or 6, and also some were successful with factory resets. On some of my old lcd tvs in the past I would get similar rolling blobs of black and it was due to the tab bonds becoming loose, which I made workable again with shims or tape which was easier with the old tvs because they had a nice big metal frame to work with. Not sure if it would work as well if at all with the newer tvs tho.

Thanks for this Sony. I'll see about the power button reset before i look into a service menu reset (which would be difficult to do with a blacked screen).

[KYBOSH]

Anyone know which Key Combo you need to press to enter into the Service Menu for the TU7000 series?
I have found a list of 13 possible combinations ....

[Davi.p]

Ok, but you did not tell wich board you've changed, the main board? Can you remove the heatsink shield and place a good very bright photo of it? (preferably near 2000x2000), i see the tcon circuitry is integrated with that and needs voltage injecting, so a bench psu is suitable..
but in case you have changed it maybe the fault is in screen's strip boards, especially tiny caps, so you need to locate wich pins connects the 15-17v rail to the panel, and inject some voltage gradually to these until the bad cap turns hot and locate it.. i will tell you how larer..


this is a difficult task, the other alternative maybe easier, is to use the tv long enough until the working state shortens until the bad cap turns completely shorted and you can easily locate it with multimeter.. bye

[Diah]

Anyone know which Key Combo you need to press to enter into the Service Menu for the TU7000 series?
I have found a list of 13 possible combinations ....

even if there are 20 ways of combination to inter service menu... but the tv in standby and try one by one.