LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

[Hakuu]

Hi There,

This TV was auto switching off after few seconds with some vertical lines on the screen, so got a new TCON board and replaced it.

After replacing the TCON board it was working fine and i set it up with everything, used for few hours, then had the bright idea to update the software on it. During the update process, TV switched off and now no audio or video. No relay switch sound.

More Details

TV Model - LG OLED77G1PUA

Got the same exact TCON board from TVPartsToday and replaced it. But didnt transfer the EPPROM data (didnt know that it was required, still am not sure if that is required, still got the original TCON board)

When i remove the second ribbon cable from the Main Board to the TCON board the TV turns on and if i connect my Macbook Pro it detects as a second display, but no video or audio on the TV) there is red light on the optical port and it seems like the TV is on and working without any video on the display

When i plug the second ribbon cable back, TV shows the setup screen (with connect TV Remote page) for a second and then turns off.

Is this TCON board and Main Board firmware mismatch problem ? how can i fix that ?

Do i need to transfer the data or the EEPROM from the old board to the new one ?

Is this a Panel Short or any panel issue ?

LG support will give me new panel as its more an year old now ?

Picture of the TCON board and Main board is attached with the ribbon cable from main board to TCON board marked as 1 and 2 ( what they are called ? )

I am a CS engineer, so got the skills and tools required to do basic TV repair.

[Diah]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

from begin you have short cells on screen module. non repairable.

[EazyBone]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

I thought g series had 5 year warranty on them starting at G1. I recently had no video/audio and replaced tcon and main board from same broken tv and fixed for me. I'm here just trying to learn not sure can give a lot of advice.

There was a YouTube video from shop jimmy that said my panel was shorted if I had the exact problem they show on video .. but not true because it fixed lol. Good luck

[Diah]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

I thought g series had 5 year warranty on them starting at G1. I recently had no video/audio and replaced tcon and main board from same broken tv and fixed for me. I'm here just trying to learn not sure can give a lot of advice.

There was a YouTube video from shop jimmy that said my panel was shorted if I had the exact problem they show on video .. but not true because it fixed lol. Good luck

your case are different.... as you dont have line on screen.. just screen out and when you did screen t-con stand alone test... yours t-con didn't start / screen remain black) i didn't wrote further to you because from start you wrote you bought already replacement t-con and this is the issue..

here he have line on screen... this is cells

[Hakuu]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

your case are different.... as you dont have line on screen.. just screen out and when you did screen t-con stand alone test... yours t-con didn't start / screen remain black) i didn't wrote further to you because from start you wrote you bought already replacement t-con and this is the issue..

here he have line on screen... this is cells

I did the test again, but this time removing the ribbon cables from the Tcon to the Panel (to rule out the panel being short), but got the same exact results, the moment I plug in the second ribbon cable from main board to Tcon, the TV turns off. When the TV worked for few hours, there was no lines or any issue with it, it was perfect until I updated the software. If the Panel is short, then when i remove the panel from the Tcon the TV should stay up ?

[Diah]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

This TV was auto switching off after few seconds with some vertical lines on the screen, so got a new TCON board and replaced it.

this what you wrote at first post and this is cells issue

I did the test again, but this time removing the ribbon cables from the Tcon to the Panel (to rule out the panel being short), but got the same exact results, the moment I plug in the second ribbon cable from main board to Tcon, the TV turns off. When the TV worked for few hours, there was no lines or any issue with it, it was perfect until I updated the software. If the Panel is short, then when i remove the panel from the Tcon the TV should stay up ?

1- the second LVDS cable you disconnect and the TV remain on at it, the SOS signal T-CON send it ( because panel had issue ) going thru this cable to MICOM to turn off the PSU
2- disconnecting Panel ribbon cable between it & T-con didnt work on OLED, this was only working on LED or Plasma screen
3- SOS registered at T-CON firmware ( SPI ) and it remain at lock state to prevent Panel cell from getting fire. this could also make the MB at lock state too.

working around to show you that panel issue... keep all LVDS & ribbon cable in place as original connected only disconnect the 20-24V socket between power boards and t-con driver boards ( disconnect it from power boards side ) turn on and wait hope you will see the audio output optic port lit red.

if yes. mean your t-con come out from lock state.... at this case while its on plug back the socket you disconnected early... screen will light on and if you are lucky will remain on

[Hakuu]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

this what you wrote at first post and this is cells issue



1- the second LVDS cable you disconnect and the TV remain on at it, the SOS signal T-CON send it ( because panel had issue ) going thru this cable to MICOM to turn off the PSU
2- disconnecting Panel ribbon cable between it & T-con didnt work on OLED, this was only working on LED or Plasma screen
3- SOS registered at T-CON firmware ( SPI ) and it remain at lock state to prevent Panel cell from getting fire. this could also make the MB at lock state too.

working around to show you that panel issue... keep all LVDS & ribbon cable in place as original connected only disconnect the 20-24V socket between power boards and t-con driver boards ( disconnect it from power boards side ) turn on and wait hope you will see the audio output optic port lit red.

if yes. mean your t-con come out from lock state.... at this case while its on plug back the socket you disconnected early... screen will light on and if you are lucky will remain on

Thanks Diah.

This worked, and the TV is up and running now, I have been testing it for the last 3 hours and its absolutely perfect. Dont know how long it will work thou.

Now, what might be the problem, panel is still bad ? how to prevent it happening again ? Should i reduce the screen brightness or something ?

Didnt update the software, will keep it like this for few days then will think about updating it.

[Diah]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

it still panel... but if you leave the tv with out moving it or do any pressure on the screen will last long... some time with OLED when it show lines we click on screen with finger smoothly on the line area while its off to let the cells in contact when the line white color only
i would suggest don't update right now when the screen show fine.. to avoid if the last firmware the SOS script section at new firmware more sensitive to make the tv turn of or go lock state... keep it

[Hakuu]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

it still panel... but if you leave the tv with out moving it or do any pressure on the screen will last long... some time with OLED when it show lines we click on screen with finger smoothly on the line area while its off to let the cells in contact when the line white color only
i would suggest don't update right now when the screen show fine.. to avoid if the last firmware the SOS script section at new firmware more sensitive to make the tv turn of or go lock state... keep it

Updated the software, and also run that pixel cleaning things for an hour, everything seems fine. I have access to a service remote, is there anything I can change on the inStart or EzAdjust settings to prevent this TV from dying again or prolong its life ?

[Diah]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

I have access to a service remote, is there anything I can change on the inStart or EzAdjust settings to prevent this TV from dying again or prolong its life ?

only you can within In_START to read the error code register at time it was wont start.
IN_STOP did it once will bring the TV to factory state.

[Hakuu]

Re: LG OLED77G1PUA - No Video / Audio after a TCON Board change and Software Update

only you can within In_START to read the error code register at time it was wont start.
IN_STOP did it once will bring the TV to factory state.

Yes, I can see lots of "turnoff by bdp error 7", its definitely a panel power issue, I will check with LG support if they can replace the panel under warranty.

Thanks for your support, its till up and running.