LG75SK8000PTA Blue screen no image shadows showing

[wazzadj@hotmail.com]

Hi Folks ,
I have a 75 inch Led Lg tv
Model LG75SK8000PTA
that has a strange problem
i have no sound no picture ,
i can turn it on and the backlights come on and I get a very dull Blue screen
when I use the remote I can see a response like its trying to show a picture on screen but cant get a image just very dark shadows moving around the screen
I have checked all the smps voltages are all ok and present
I have replaced the Tcon board with a new one from LG
I have checked and cleaned and reseated SVDC cables
I have 12v at SMD fuse on both sides at the tcon board
so I think I have a good Main and tcon board signal present
my backlights seem bright enough from the back of panel when looking at them
what could be the issue
Can i follow the LG tcon test as per the training Manual on here
your help is appreciated
Thankyou

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

nano cell, a good panel, i would start with reset the TV via IN_STOP command.

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

nano cell, a good panel, i would start with reset the TV via IN_STOP command.

Please can you explain further to NANO CELL reset the TV via IN-STOP command

cheers

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

Please can you explain further to NANO CELL reset the TV via IN-STOP command

cheers

we talked allot about IN_STOP. to know more you can google it or download it from this POST

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

Thanks Diah for your assistance
The problem i have is the TV has no picture at all
just a faded BLUE screen NO Image is possible or Audio so i cant perform IN-Stop on it
all my voltages are present and correct
I have a new Tcon board
when i unplug the right hand side SVDC cable on the tcon i get a white bar on the screen nice and bright picture, but the left hand side of the screen remains dull blue , i swaped to the right by unplugging the left and plugging the right back in on the Tcon and i still do not get a image it just remains blue
I do get a very defined response from the remote control you can see shadows moving on the screen so i believe the main board is ok
I have 13.2v at the fuse on the TCon board & 12v present on the 4pins on the 51 pin SVDC cable
Is the lower Buffer Boards the issue maybe

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

when i unplug the right hand side SVDC cable on the tcon i get a white bar on the screen nice and bright picture, but the left hand side of the screen remains dull blue , i swaped to the right by unplugging the left and plugging the right back in on the Tcon and i still do not get a image it just remains blue
Is the lower Buffer Boards the issue maybe

show us please here photo on how it look the screen when you disconnect the ribbon cable between T-CON and panel ( you called them SVDC ) prefer with signal .

BTW. try to access to lower Buffer Boards of the panel...you have on each side at this boards U ribbon cable at the middle . disconnected ..start with the fade blue side.. also prefer with signal..

any further diagnostic always helpful if you upload photos over here showing the issue..

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

Sorry Diah , my Bad i will upload some photos tomorrow
the ribbon cables are the ones I am referring to coming from the TCon board at the bottom I will post up some pics to make it clearer to see what I am describing

Thankyou

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

I have now uploaded high res pics of the tv boards and the Tcon right hand cable disconnected as per your instruction with a source connected
when I connect both tcon ribbon cables I get a dark blue faded to black screen
no IMAGE No SOUND no channel or input display
I have tested the tcon fuse ok 12v
i have tested the lower FCC board where the tcon ribbon cables connect
i have 13v plus 3.6v lines
I don't believe it is the main board as I can see a response from the smart remote control like dark shadows moving when I press the remote

your help is appreciated
thankyou

show us please here photo on how it look the screen when you disconnect the ribbon cable between T-CON and panel ( you called them SVDC ) prefer with signal .

BTW. try to access to lower Buffer Boards of the panel...you have on each side at this boards U ribbon cable at the middle . disconnected ..start with the fade blue side.. also prefer with signal..

any further diagnostic always helpful if you upload photos over here showing the issue..

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

Update i am still waiting on a LG service remote to be delivered so I can Perform a IN-STOP command

I have now uploaded high res pics of the tv boards and the Tcon right hand cable disconnected as per your instruction with a source connected
when I connect both tcon ribbon cables I get a dark blue faded to black screen
no IMAGE No SOUND no channel or input display
I have tested the tcon fuse ok 12v
i have tested the lower FCC board where the tcon ribbon cables connect
i have 13v plus 3.6v lines
I don't believe it is the main board as I can see a response from the smart remote control like dark shadows moving when I press the remote

your help is appreciated
thankyou

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

I have now uploaded high res pics of the tv boards and the Tcon right hand cable disconnected as per your instruction with a source connected
when I connect both tcon ribbon cables I get a dark blue faded to black screen
no IMAGE No SOUND no channel or input display
I have tested the tcon fuse ok 12v
i have tested the lower FCC board where the tcon ribbon cables connect
i have 13v plus 3.6v lines
I don't believe it is the main board as I can see a response from the smart remote control like dark shadows moving when I press the remote
your help is appreciated
thankyou

please check the following.
1- check on the side of Main boards sockets ( which it come from PSU ) if you have 20V.?
2-unplugg the wifi socket and check your TV screen.

Update i am still waiting on a LG service remote to be delivered so I can Perform a IN- command

if the points 1&2 above was done and no change. lets wait for yours LG service RC to send IN_STOP. if no change then it may we are facing BGA issue at the Main boards.

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

Hi here is updated Photo of Original Fault condition showing No image
Backlight on

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

DIAH just a quick Note ...
when I first received the tv it was showing this condition
so I thought it was a Tcon issue Reballing BGM chip
So I have a Heat bed I use for doing Ipads screens etc So I laid the Board down Chip face down & heated it for 4min at 150deg i then plugged it back in and I had the channel number and LG Logo come up on the screen for 1 Minuet
So that's why I thought it was the TCON board and ordered a new one
I have since replaced the TCON board with the new one from LG and the Photos of the Blueish screen is what I am presented with now
I am a little confused as to why the old Tcon Board responded after I heated it for a sec
But the new one wont respond at all ?

Anyway I will try the following instructions you stated and report back
Again thankyou for your assistance

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

I cant find the Wifi Module to disconnect it WHERE IS IT LOCATED ?

When I measured all the voltages from the back of the PSU plug going to the MAIN i get all the correct voltages
according to the silkscreen table on the PSU board
pin 1 =20v
Pin 3=20v
pin 5= GND
Pin 7=13.2v
pin 9= GND
pin 11= GND
pin 13= PWR=ON
PIN 15=GND
PIN 19=20V
PIN 21= GND
PIN 23=DRV-ON
PIN 25=GND
PIN 27=V-SYNC

PIN 2= 20V
PIN 4= 20V
PIN 6=GND
PIN 8= 13.2V
PIN 10= GND
PIN 12=GND
PIN 14=PDIM-2
PIN 16=13.2V
PIN 18=13.2V
PIN 20= 20V
PIN 22= GND
PIN 24= PDIM 1
PIN 26=SCLK
PIN 28=SIN

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

DIAH just a quick Note ...
when I first received the tv it was showing this condition
so I thought it was a Tcon issue Reballing BGM chip
So I have a Heat bed I use for doing Ipads screens etc So I laid the Board down Chip face down & heated it for 4min at 150deg i then plugged it back in and I had the channel number and LG Logo come up on the screen for 1 Minuet
So that's why I thought it was the TCON board and ordered a new one
I have since replaced the TCON board with the new one from LG and the Photos of the Blueish screen is what I am presented with now
I am a little confused as to why the old Tcon Board responded after I heated it for a sec
But the new one wont respond at all ?

Anyway I will try the following instructions you stated and report back
Again thankyou for your assistance

now its clear.. as i thought first to run IN_STOP. the issue you have now that the replacement T-CON firmware on SPI ( empty or didnt match the Firmware on the main boards ) so you have functional TV with NO Picture.. but still you said there are no sound too... maybe because you didnt switch the source signal correct as you cant see screen

any way.. put the replacement T-CON always in use. and try downgrade or upgrade the firmware.. In-STOP will do it also to register T-CON & write from Temp the firmware at T-CON again. and do reset to main Firmware.

if this didn't work then you need to write it manually by replacing the spi flash of the old on the new one OR by dump the old and flash it on the new. ( ONLY IN CASE the 2 T-CON BOARDS 100% ARE IDENTICAL )

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

oK diah Thankyou for your asssistance and expert help
i will try the N_STOP command

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

OK Diah ,
I have now received the LG Service remote and performed a N-Stop command
but because I have no image I don't know if it is working
I press 0413 and the tv turns on out of standby i then press N-stop on the LG service remote and that is all
The tv turns off and that's it , I turned it back on and NO image
Can you assist further please

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

OK Diah ,
I have now received the LG Service remote and performed a N-Stop command
but because I have no image I don't know if it is working
I press 0413 and the tv turns on out of standby i then press N-stop on the LG service remote and that is all
The tv turns off and that's it , I turned it back on and NO image
Can you assist further please

i recieved yours PM .. please keep writing over this threat only.

IN_STOP how its work. when the TV ON (signs of the set are on : back light on. optical audio socket red led lit on ) front panel led indicators on most LG will be off when the set ON, and lit steady Red when set at standby or blinked if there are error so we don't give attention on it if its off.

so. if you have the sign the set ON. send IN_STOP follow it with 0,4,1,3 the front panel led should turn on RED as standby... that's all... turn on the set and give time as the first install will be in place.

if the issue after in-stop remain same as you showed us before.. and the T-CON was okay,, i would inspect the LVDS cable / sockets from both side either on main boards too.. LVDS & ribbon cable used by LG later 2018 sets and forward are cheap one where we found many burned line specially on LVDS by nano cells & OLED.

thought repairing and following trouble shooting via writing hard task to me as i am non native english person.

[nomoresonys]

Re: LG75SK8000PTA Blue screen no image shadows showing

If no luck maybe try re-heating your board the one you already heated that is, to 217 C, maybe bring it up to temp slowly and let it there for about half a minute then bring it back down slowly as to try not to thermal shock it.

[wazzadj@hotmail.com]

Re: LG75SK8000PTA Blue screen no image shadows showing

Hi Diah
I received service remote and tried N-stop that did not work
so I ordered and I put a brand new Mainboard in
I have an instruction sheet that came with the mainboard from LG
stating that I have to follow a 3 step process to make it work
1. I have to make a USB disk and download from GPRS website portal a special firmware patch
2.then I have to install it on the tv
3.then I have to change the ID serial country number
then I have to perform a N=stop command from the service remote.
Problem is I can't access the GPRS portal as i am Not an authorised service agent so i am unable to download the file required

I have checked the LVDS cables on the tcon board and the ffl boards
they seem ok

[Diah]

Re: LG75SK8000PTA Blue screen no image shadows showing

Hi Diah
I received service remote and tried N-stop that did not work
so I ordered and I put a brand new Mainboard in

you make it complicated and lost as we here the reader lost too.

Now you have Empty T-CON with Empty Mainboards.. so if you cant have the patch firmware at any reason.. you need to put back yours Original Mainboards in place... then take out the SPI flash from the original T-CON, dump the firmware of it and write ( program ) it on the New T-CON SPI. so it should be and i did wrote it at the end of post #14