LG 55" Curved Model 55UG870T - No picture

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Too bad you don't have an extra mainboard to try in it.

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Well, guess there isn't much to lose by trying a diy reflow of the bga.

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Are you getting voltage to your components on your panel driver boards.

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Here's what Android Authority has to say about curved tvs: https://www.androidauthority.com/cur...-cons-1203697/

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

Not sure if the lvds cables are perfect. I checked the contacts on both sides with a magnifying glass and did not notice any issues.

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

This is a real head scratcher for me, I hope someone can solve it, will be watching this one.

[Storyteller12]

Re: LG 55" Curved Model 55UG870T - No picture

It’s the mainboard for sure. Kinda just discovered this by accident on a OLED I’m working on.

Is there an ic labeled 100GEA on the mainboard? If so it’s most likely that chip. You can replace it however it seems it needs programmed to work properly. You can update firmware to program it but if mainboard is on latest update you will have to downgrade first and then upgrade.

[Diah]

Re: LG 55" Curved Model 55UG870T - No picture

screen switches to pattern color 100% LVDS pins short... on the cable or the its sockets from both side..
BTW you recieved the set and both was disconnected... so it sound some one try to repair the LVDS

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

I was thinking the same as Diah but wasn't sure, think I would try a different cable and or look those sockets over very closely, maybe try a little pressure on the connections of those sockets, see if there's any change.

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

I will double check it this week

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

Today i will remove the LVDS cables and clean the connector sockets and ribbons contacts with benzene and re-seat. Will get back to you once tested.

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

screen switches to pattern color 100% LVDS pins short... on the cable or the its sockets from both side..
BTW you recieved the set and both was disconnected... so it sound some one try to repair the LVDS

No Diah, the TV was untampered. I did a test and removed the LVDS cables because i know that on some tcon's if you give the panel power but no data (by unpugging the LVDS cables)then the tcon goes into self test mode.
I can even take photo of the contacts on both sides and show you there is no short or broken points
on the LVDS cable, nothing visible anyway.

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

I was thinking the same as Diah but wasn't sure, think I would try a different cable and or look those sockets over very closely, maybe try a little pressure on the connections of those sockets, see if there's any change.

It seems that if just one contact does not make a proper connection you can get a blank screen. Am i right? I will have to put my multimeter on diode beep test and check for continuity on all pins. That is 51 pin and 41 pins.

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

An Update,
Hi there NoMoreSonys,
I managed to download the exact schematic for this LG tv from elektrotanya.com
I removed the main board heat sink to expose the main processor and video processor. Upon starting the tv i felt the main processor is running ice cold. This means the chip is getting no power, right. It's missing the core voltage (1.05V @ 10A). The DC to DC converter IC is receiving +12V, the power enable pin goes from 0V to 3.5V but the output does nothing not even trying to give current. The resistance measurement from the output to ground on the 1.05V rail is 270 ohms, no short there. Even if ordering the part was an option, who says that the reason for failure isn't perhaps the video processor??
Now knowing what shit is available on Aliexpress i will not be looking to fix this board but rather replacing it. Now that i am 100% sure i can go ahead and get it. The most expensive main board i will ever would have bought so far.
I will update you once i get it running.
Thank for your help so far.
Angelos

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Being a curious cat, I would do a diy reflow while waiting on the boat, here's a proper one but there are many diy's on youtube, don't care for any of the oven ones, tends to melt things, I do like the one by 12voltvids, he uses an old repurposed halogen lamp: https://www.youtube.com/watch?v=IkFCE42zoLM

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

An Update.
Replacing this very expensive mother board got this tv fixed. The kicker, none of the smart functions work because the tv is 8 years old and not supported by LG anymore. Nice hey?

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Glad it's solved, that is unfortunate about the functions, it's a shame the tv manufacturers don't inform buyers that their apps and such may be abandoned by them, I guess whenever they decide to.

[lotas]

Re: LG 55" Curved Model 55UG870T - No picture

An Update.
Replacing this very expensive mother board got this tv fixed. The kicker, none of the smart functions work because the tv is 8 years old and not supported by LG anymore. Nice hey?

The firmware most likely needs to be updated; it was released only a year ago.
Or you bought a motherboard with a different region and it does not support your region.

[angelos]

Re: LG 55" Curved Model 55UG870T - No picture

The firmware most likely needs to be updated; it was released only a year ago.
Or you bought a motherboard with a different region and it does not support your region.

Now that you mention it, i did have a region code issue. The LG tech's told me to change the region code. I did so but none of the smart functions worked. Youtube would just show loading. The browser was out of date and would not display HTML pages correctly etc. They simply said i must get a firestick or android box to continue.
This set has gone out to the client. The TV is 8 years old apparently.
Thanks for your input so far.

[nomoresonys]

Re: LG 55" Curved Model 55UG870T - No picture

Yep, I believe they were on the 2.5 version of the OS back then.