Lg oled55b8 t-con question

[reassor]

There is 2 sia ics and in 1 section where u see dots on the coils i have 2.2ohm there and there is no voltage on them at all.

Also i read in other topić how psu works on these tvs and when u pług it in there is constant 40w draw from wall. When I unplug display from tcon it drops 10w when I unplug tcon it drops another 10w (unplug done w/o power ).

I'm mostly sure its main board cpu cause no sygnał to turn on 24 volt for panel and its constant draw.

For now I'm just curios about these w coils . Could not find any datasheet for ic thats the lines go to.
would just like to know if that's normal?

Thx

EDIT:
Also all GND pads (with mounting holes) have a 2R2 resistor and i can meassure 0 OHM from these coils to the other side of the resistor (is it some kind of isolated gnd?)

[Diah]

24V EVDD depending on SW & HW,
if the T-CON generate SOS flag and send it to MB via the lower LVDS ( the one close to Screen Module ribbon ) , then this flag will let the MICOM on MB go to sleep / protection mode... as well the T-con self. to wake them up need to send via service remote Power ONLY or IN_STOP commands, after separate the 24V EVDD from circuit or separate the lower LVDS from system to stop transferring the SOS FLAG..

T-CON & Screen Module are one depending system can be test and run as Stand alone. after we disconnect them from the MB as well disconnect the MB from PSU. and we fed the them with VIN 12V & EVDD 24V

[reassor]

24V EVDD depending on SW & HW,
if the T-CON generate SOS flag and send it to MB via the lower LVDS ( the one close to Screen Module ribbon ) , then this flag will let the MICOM on MB go to sleep / protection mode... as well the T-con self. to wake them up need to send via service remote Power ONLY or IN_STOP commands, after separate the 24V EVDD from circuit or separate the lower LVDS from system to stop transferring the SOS FLAG..

T-CON & Screen Module are one depending system can be test and run as Stand alone. after we disconnect them from the MB as well disconnect the MB from PSU. and we fed the them with VIN 12V & EVDD 24V

Thank you. Im intrested in this PMIC section especialy these coils (shorted?)
When i plug the tv it turns the standby light on and just sits at 40W draw and cpu + tcon mcu (and its ram get very hot). It just sits like that.

If i knew what voltages can be produced at these coils i would just inject to find the short (ill probably do that with 1V and see)

Thx for the testing tip.

EDIT: just lookat at this tcon again and these coils are to gnd (wierd for me i do laptops)

[Diah]

Thank you. Im intrested in this PMIC section especialy these coils (shorted?)
When i plug the tv it turns the standby light on and just sits at 40W draw and cpu + tcon mcu (and its ram get very hot). It just sits like that.

If i knew what voltages can be produced at these coils i would just inject to find the short (ill probably do that with 1V and see)

Thx for the testing tip.

1-there are no way coils to be shorted because they are low Ohm, and their job to re filter noise ( Freq filter ) on rail.
2- the MB if find SOS or over load will cut Power_ON signal rail to PSU, so PSU will turn off.... then how you said the CPU got very hot !!!

[reassor]

All caps have gnd on same trace as these coils even the port on top you can see is to that trace.

CPU and mcu on tcon get hot and psu not shutting down. there is no 24v on signal. standby light is on

as for tcon whole gnd is separated by 2.2 ohm resistors to chassis. You can see 1 resistor on top left to the chasis gnd pad. (sorry for the quality)

[Diah]

All caps have gnd on same trace as these coils even the port on top you can see is to that trace.

CPU and mcu on tcon get hot and psu not shutting down. there is no 24v on signal. standby light is on

as for tcon whole gnd is separated by 2.2 ohm resistors to chassis. You can see 1 resistor on top left to the chasis gnd pad. (sorry for the quality)

standby ON. so no EVDD 24 or VIN 12V.
disconnect the lower LVDS from T-CON and the 24 EVDD socket on T-CON plug in wall if standby on turn it on by remote. check VIN 12V and EVDD 23 on PSU, also check the audio optic on MB it it lit red on

[lotas]

These inductors (chokes) are soldered to gnd with one terminal to convert negative voltage relative to gnd.

[reassor]

These inductors (chokes) are soldered to gnd with one terminal to convert negative voltage relative to gnd.

Thats what i wanted to know. on 1 diode i had something around -6v and -8v on the lower one.

[Davi.p]

Hi, i don't understand this thread, there is no fault description.. yes the coils at gnd are in every tcon, almost..

[reassor]

Hi, i don't understand this thread, there is no fault description.. yes the coils at gnd are in every tcon, almost..

Sorry for late response but fault is described i think.

No video/audio + red led + constant draw of 40w (20 cpu, 10 tcon and 10 panel (know by disconecting))
You can hold the power button for 10-20 sec (varries - not always work) and then it will shut off to no led and 0.9W after next press it blinks 3 times and goes back to 40 W (no led).

CPU - hot
Tcon MCU - hot
CPU ram is cool
Tcon ram is hot
Onviosly no 24v on signal (can be forced - psu ok)

Rest of voltages are present.
After disconecting lower (close to ribbons) lvds cable no change.

Did MB CPU reball (when i took it off it looked like 1 corner had cold soldier)
Now it sits good but there is no change.

Got 2 options

new board or tcon (i think MB but not 100% sure )

any way to make sure?

[Davi.p]

I guess there is a bad standby software, if this is a model with a fairly unknown micro controller on main.board, this appears to be a common issue on some oled lg
models.. post MB model.. you can also make a screen.self test.. check my other posts on similar lg tv

[reassor]

How do u screen test on TV that's not showing video?

[Davi.p]

Yes i see the microcontroller, near the pads for 2 microswitches, for the screen test i've already said to search the forum.. search lg oled threads

[reassor]

Did drv_on + pwr_on and vt12v with main board unplugged and lvds lines out. No picture. 40w draw.

Do I need to spend another half a day looking at your posts or will I get an actual response if that's a good way to test the panel?

[Davi.p]

That is not enough for me, you need to wire jumper the PSB 12v to the tcon fuse near LVDS from Main board

[lotas]

That is not enough for me, you need to wire jumper the PSB 12v to the tcon fuse near LVDS from Main board

This is not a simple T-CON, and simply supplying 12v won’t do anything...

[reassor]

Cannot see any fuses on this side. What line need to have 12v on this photo?

[reassor]

standby ON. so no EVDD 24 or VIN 12V.
disconnect the lower LVDS from T-CON and the 24 EVDD socket on T-CON plug in wall if standby on turn it on by remote. check VIN 12V and EVDD 23 on PSU, also check the audio optic on MB it it lit red on

Did that. Got all voltages. Did the jumpers on pwr_on + 12v on and drv_on. No picture. Tcon hot af

No red light on spdif out no usb power either when all is plugged in as supposed to be and I switch mobo on somehow with remote - need to be patient with that since it does not react correctly.

Just to add when standby light is on 12v is present and all voltages on mb and tcon except 24v.

[Davi.p]

ok there is no 12v on lvds, so i don't know how to proceed, this tcon is different..

[reassor]

There is 2 switch sposts on mb. 1 is forcing standby the upper 1 is doing something just dunno what. Are there any schematics for these contraptions? Never did oled before.