LG OLED 55EG9100 won’t power on

[Storyteller12]

I have this set and the standby light comes on but nothing happens when pushing the power button.

Opened it up and did some testing and on the tcon I believe I found a short to ground. I circled the part. There is another one next to it that is not shorted to ground. So I was assuming this was my problem.

Thanks for the help

[lotas]

Re: LG OLED 55EG9100 won't power on

This choke (inductor) must be on gnd, since a negative voltage (-) VGL is formed on it.

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Ok, thanks for clarifying. I've never troubleshot OLED before. Any idea where to start troubleshooting now?

I've attached pics of the rest of the tv/ boards
Thanks

[lotas]

Re: LG OLED 55EG9100 won't power on

In this model, micom (Renesas) is responsible for switching on; it contains its own firmware, check the power on it (3.3v), as well as the voltage on the dc / dc converters (chokes) and the resistance on them relative to the ground.

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Attached is the readings. I get 0v going to the ic2300.

Does that mean the ic labeled 100GEA is bad?

[Diah]

Re: LG OLED 55EG9100 won't power on

if the PWB turn off after SOS signal the micom will be stall to zero..
put every things back as original only keep the socket between T-CON and PWB ( black one ) disconnected... turn on and check if you have the Audio opric on MB lit red.. and you have 12-24V on the MB socket or on the PWB side

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

I don't get any red light from optics and o 12v or 24v on pwb or main.

Is this the cable you wanted to remove?

[Diah]

Re: LG OLED 55EG9100 won't power on

yes correct.... it mean you need to test the PWB as stand alone to be sure it work and start on to provide the requirment V to MB.... i wrote many time how to on OLED threats

if you are not sure... u need to upload the photo of the socket between PWB and MB and the print chart on it... and test the PWB alone with out any socket connect to it just wall socket... see if the STB V 3.5 V or higher

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Ok thanks. I tested and only get 3.5 standby. I circled the The ones that get 3.5. The other one with a line shows nothing. No 12v or 24v. No power/ reading on any other pins.

I plugged everything back in and when I push the power button I do see the voltage on mainboard drop to 0 from 3.5v. So it is registering the power button being pushed.

[Diah]

Re: LG OLED 55EG9100 won't power on

PWB stand alone test only the PWB plugged in wall socket... jumpers
between STB 3.5V and Power On... .. this should turn on the PWB to provide 12V on socket pins
as first jumper in place make another jumper STB 3.5V to DRV_ON. this will generate 24V on the socket we talked before between PWB and T-CON

if this voltage you have at stand alone test.... mean yours issue at MB... if not then need to work on PWB.
Note... to avoid any mistake at assigned pins you are going to make jumpers... use MAx 1K Ohm in Jumper to avoid any damage if you missed with wrong pins.

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Thanks for walking me through it.

I powered on and got all 12v and 24v rails. So on to the mainboard

[Diah]

Re: LG OLED 55EG9100 won't power on

good... so yours PWB OK... at MB there on OLED some ponits need to consider it.. the Last ate condition... mean if before the fault if the tv was on STB will go back to STB after power it on from local TV power on. or just plug it in wall socket... so need RC to power it on.... after that if you plug it out from wall socked and again in will start immediately (as the last state was On )
before you have only 3.5V STB. ( as you wrote ) so this point accurate
second... you have on the NB 2-3 micro switch to reset DC-DC- MICOM-and start script firmware... you need to try to press one by one and keep press for 10 second while you plug it in wall socket ( when the last state ON as i wrote before )

all above points should all cable ribbon LVDS connected as original... ONLY the the black wire socket between PWB & T-con disconnected.. and keep it disconnected until you see the OPTIC audio port lit red

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

I switched out the ic Lotas mentioned labeled 100GEA and TV now turns on and cycles red, blue, yellow, green but has horizontal lines across the screen.

The mainboard I took it from had this same symptom and we scrapped the tv because the screen was cracked anyway. So possible the IC I replaced with is bad.

I do have another to try but wanted to get opinions here before swapping it out again

Can

[Diah]

Re: LG OLED 55EG9100 won't power on

show me the line on screen at color pattern state

edit:
if cable coneccted and after power on patteren color show mean the MB provide 12 V T-CON. but no signal whixh lead T-con to start its own firmware.... you still have issue on MB.. or the t_CPN firmware didnt pass the first start script.... disconnecting the 24V and turn on the tv until you have Optic lit red keep it on for awhile then as its on.. plug back this socket

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

I switched the ic out again and the tv does turn on and show display, however the it’s still slightly messed up on 3 quarters of the screen

Obviously the red light on the optical port is working now

[Diah]

Re: LG OLED 55EG9100 won't power on

lotas wrote before micom had own script at firmware...now time to downgrade or update the firmware to let all parts will work together

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Ok. Any particular one I should try first?
Do I just update through internet or through usb with firmware?

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

Updating is a no go as the tv is already on the latest version 04.06.75.

So I left with downgrading. Any good guide on how to do this?

[Diah]

Re: LG OLED 55EG9100 won't power on

Updating is a no go as the tv is already on the latest version 04.06.75.

So I left with downgrading. Any good guide on how to do this?

there are several ways to downgrade .. from PC Apache server via LAN.( most recommend ).. or USB and via the browser of the TV... .. you may try too to send IN_STOP via Service RC. the last firmware TEMP saved on TV and it will roll back with this command .... hope will solve the issue... if not then downgrade

[Storyteller12]

Re: LG OLED 55EG9100 won't power on

I will try in stop and hope that there is a TEMP saved firmware. If not I have read up on downgrading. However the problem I have is I cannot find an older firmware for this model. I tried the Korean LG site and also looked on the Russian site. But didn’t see anything for 55eg9100 or any of the reference models for this TVs firmware