LG 55EA970V OLED / black screen

[pedrolane]

Re: LG 55EA970V OLED / black screen

Again I fully appreciate all your advices.

Here are some pictures of the whole set without backplate.

You can see the naked tcon. So I've tested the fuse on the right (5A / 125V / it's ok) and the voltage on power ribbon.

The module on the right is the wifi / bluetooth module

[Diah]

Re: LG 55EA970V OLED / black screen

what are you doing.... i know you are diving wrong..
explain this miss test . who told you to do this ?
and look where are the 20V Fuse. there need to check 20V from both side not on the socket..

[nomoresonys]

Re: LG 55EA970V OLED / black screen

Diah I think you're going to need a translator: German to English to French:

[pedrolane]

Re: LG 55EA970V OLED / black screen

On the picture LVDS (edit: LVDS were both unplugged on picture) are not plugged because I took the picture while between a MB swap. But all the tests I've made were done with both LVDS plugged (until advised the contrary). Also my DRVON shunt is opened on the picture, but I've made the recent test with a scotch-lock to close it.

I post one photo of 19.9v at TCON power entry to show you I (quite) know how to get a DC voltage, but I've made several other measures. I didn't spot the left fuse, my bad.

The 2 fuses on tcon are okay on diode test
And the fuse on the left side (the one you circled) has 20v relative GND at each side while PWRON / DRVON.

For the fuse on the right I dont know whether it is supposed to be 20v also, but I have 0. I find it logical as this is the fuse on LVDS entry, and MB is nearly in standby mode, so does not send any signal. Right ?

[Diah]

Re: LG 55EA970V OLED / black screen

Diah I think you're going to need a translator: German to English to French:

LOL. i still have 2 posts more to reach my favorite No 3910. so will stop ... more posts more headache. time to have travel and relax.

[nomoresonys]

Re: LG 55EA970V OLED / black screen

I hear you Diah, it's getting pretty monotonous, seems like 49% are bad backlights and 49% are shorted panels...SOO borrrrrrrrrrrring.

[pedrolane]

Re: LG 55EA970V OLED / black screen

Some news.

Thanks to Diah I've made several other tests.
We provided 20v and 12v to TCON, with MB disconnected and forced DRVON. The RGB test is fine. Can we conclude the panel is not shorted ?

I've also received the replacement MB which seems (visually) in good state. But unfortunately it doesnt solve the issue, DRVON remains low.

To sum up I've changed all 3 boards and have same symptoms with all of them.
The panel seems okay as RGB color cycle is okay.

I've measured 12v on several capa and coils on MB, but no 12v go to LVDS pins.

What other test can be done ? Can I test a faulty panel by disconnecting the 4 ribbons from TCON ? Is the MB supposed to boot ?

Is it worth keep trying to save this set ?

[Diah]

Re: LG 55EA970V OLED / black screen

What other test can be done ? Can I test a faulty panel by disconnecting the 4 ribbons from TCON ? Is the MB supposed to boot ?

Is it worth keep trying to save this set ?

so it sound the panel send SOS signal however when you do the stand alone test was clean pattern displaying... so it could it pull high current..
you can try the test stand alone T-CON and panel... you know how... but now you need to check with yours DMM VDC the LDS socket at t-con side... see which pin are high ( the socket down from downside the first 11 pins ) could be there the sos signal.... if you find this you can disconnect the pin from the circuit d´so there will be no more sos signal the tv will send drv on.

also if some one have the T-CON diagram will be better to determine which pin for SOS

[Donny2derby]

Re: LG 55EA970V OLED / black screen

I hear you Diah, it's getting pretty monotonous, seems like 49% are bad backlights and 49% are shorted panels...SOO borrrrrrrrrrrring.

Surely these are the simple ones to fix and the money makers though?

[pedrolane]

Re: LG 55EA970V OLED / black screen

okay Diah, that seems a good hint !
I've found that in a troubleshoot manual :

NOTE3 (Panel Burn Detection): The Panel is also monitored by the Main board for “Burn Detection”. This indicates an internal short on its grid
lines. There is a line on the Vx1 cable P7100 pin 40 called “T_CON_SYS_POWER_OFF”.
This line is routed through R7101 and renamed to “LED_R” sent to the Micro pin 16. This line is normally 0V when the Panel is operating
normally. If the Panel's internal grids short, this line rises to 3.5V, the TV set shuts off and logs “POWER_OFF_BY_INV_ERROR” in the Power
Off Status menu in IN-START.
Additional Note: If the Burn_Det (INV_ERROR) repeats 3 times consecutively when trying to turn on the TV, the Main board will “Lock” and
will no longer turn on the TV, (Even if the Main board were put in a different TV it will still remain locked.
To Un-Lock the Main Board: It has to be turned on by using the service remote “P-Only” button. This by-passes the Burn detection. You can
check the Power off status by pressing “Exit” then entering the In-Start service menu and Scroll to Power Off Status. Look for 3 consecutive
“INV_ERROR” entries. If burn detection is the cause, make sure Software is up to date. If yes the Panel is defective and needs to be replaced.
To “Exit” P-Only mode press “In-Stop” button on the Service remote and now the Main board will be unlocked.

let me find this pin40 ...

[pedrolane]

Re: LG 55EA970V OLED / black screen

okay here is the diagram
on my mb this is pin 44, not 40.

On R7216 I have 0v when pwr off, and 0.3v when pwr on. Don't seem to be sufficient to be considered "high".

if I switch the TV on with p-only, it is supposed to bypass the "burn detection", however there is still nothing on screen.

[Diah]

Re: LG 55EA970V OLED / black screen

okay here is the diagram
on my mb this is pin 44, not 40.

On R7216 I have 0v when pwr off, and 0.3v when pwr on. Don't seem to be sufficient to be considered "high".

if I switch the TV on with p-only, it is supposed to bypass the "burn detection", however there is still nothing on screen.

i wrote to you.. the best way run the panel and T-CON as stand alone... then check on T-CON side which bin are high

power only will not solve the problem, its considered to wake up the MB in case it went to sleep mode

[pedrolane]

Re: LG 55EA970V OLED / black screen

So I've made measurements with TCON and PS only (MB totally disconnected).
PWRON and DRVON are forced on. And 12v brought directly from PS to TCON "right" fuse.
Color cycle pattern is working.

It is not easy to check with these small pins. But as far as I can tell the pin 44 "t_con_sys_power_off" on CN4 is 0v.
I do have 3.5 on pins 2, 3, 7. And 12v on 48 to 51 (back from tcon). I also have 3.5 on various pins between 11 and 40.

I've found some basic TCON schematics, I attached here.

[Diah]

Re: LG 55EA970V OLED / black screen

okay Diah, that seems a good hint !
I've found that in a troubleshoot manual :

NOTE3 (Panel Burn Detection): The Panel is also monitored by the Main board for “Burn Detection”. This indicates an internal short on its grid
lines. There is a line on the Vx1 cable P7100 pin 40 called “T_CON_SYS_POWER_OFF”.
This line is routed through R7101 and renamed to “LED_R” sent to the Micro pin 16. This line is normally 0V when the Panel is operating
normally. If the Panel's internal grids short, this line rises to 3.5V, the TV set shuts off and logs “POWER_OFF_BY_INV_ERROR” in the Power
Off Status menu in IN-START.
Additional Note: If the Burn_Det (INV_ERROR) repeats 3 times consecutively when trying to turn on the TV, the Main board will “Lock” and
will no longer turn on the TV, (Even if the Main board were put in a different TV it will still remain locked.
To Un-Lock the Main Board: It has to be turned on by using the service remote “P-Only” button. This by-passes the Burn detection. You can
check the Power off status by pressing “Exit” then entering the In-Start service menu and Scroll to Power Off Status. Look for 3 consecutive
“INV_ERROR” entries. If burn detection is the cause, make sure Software is up to date. If yes the Panel is defective and needs to be replaced.
To “Exit” P-Only mode press “In-Stop” button on the Service remote and now the Main board will be unlocked.

let me find this pin40 ...

upload this troubleshoot manual ... it may belong to other model.... but LG Micom will be same... pin 16 , so from the micom chip you can follow too

[pedrolane]

Re: LG 55EA970V OLED / black screen

Micom pin 16 is labelled LED_R which is connected to T_CON_SYS_POWER_OFF (pin 44 of LVDS). I put the schematics on post 31, there are some R and capa around.

Do you think I may "break" the copper path to disconnect this pin ? I can remove R7216 as well. I've never measured 3.5v on this pin, so not sure if this is a good way to go.

I put the "training guide" here. There are some useful infos.

[Diah]

Re: LG 55EA970V OLED / black screen

Micom pin 16 is labelled LED_R which is connected to T_CON_SYS_POWER_OFF (pin 44 of LVDS). I put the schematics on post 31, there are some R and capa around.

Do you think I may "break" the copper path to disconnect this pin ? I can remove R7216 as well. I've never measured 3.5v on this pin, so not sure if this is a good way to go.

I put the "training guide" here. There are some useful infos.

why not.. do it.. but before removing.. you need to check in reality the pin 16 way to R and then to LVDS 44 socket....
by the way high are any value over 0 ... and this SOS doesn't described as current, it is pules signal

[pedrolane]

Re: LG 55EA970V OLED / black screen

I do confirm with diode test that LVDS PIN44 is connected to R7216 then to MICOM pin 16. It is qite easy to follow path on board.

But I can't understand something. If everything is plugged in place, I do not have 12v on LVDS pins 48 to 51. So the TCON is shut off. How could it send back a "panel burnt" signal on PIN 44 ?

Again thanks for your help. It's amazing how this looks fluent to you only with descriptions and pictures !
I will try to cut off the copper path of this pin on one of the MB I have, and let you know.

[Diah]

Re: LG 55EA970V OLED / black screen

I do confirm with diode test that LVDS PIN44 is connected to R7216 then to MICOM pin 16. It is qite easy to follow path on board.

But I can't understand something. If everything is plugged in place, I do not have 12v on LVDS pins 48 to 51. So the TCON is shut off. How could it send back a "panel burnt" signal on PIN 44 ?

Again thanks for your help. It's amazing how this looks fluent to you only with descriptions and pictures !
I will try to cut off the copper path of this pin on one of the MB I have, and let you know.

before when i followed with you it was there 12V to T-CON but there are no DRV_ON to have 20V-24V to Panel driver on T-CON.
it may the MB now i SOS mode.. also if you remove SOS on PIN 16 Micon. need to power the set first with power ONLY on Service remote to by pass the deep sleep state.

[pedrolane]

Re: LG 55EA970V OLED / black screen

The root issue is that there is no DRVON while power on, so no 24v on TCON.
But I neither had 12v on LVDS 48-51 pins.

However I can measure 12v near that pins on Q2301 and Q2302 (tell me if you need schematics).
I didn't analyse too much but it seems the panel_ctl (micom pin4) is down, so these mosfet are opened circuit.

It might seem logical with hypothesis the T_CON_SYS_POWER_OFF force the MICOM to keep panel shut.

[Diah]

Re: LG 55EA970V OLED / black screen

cut off pin 16 and we will see.. dont forget after do it with power only