LG OLED77C19LA Standby Issues

[Bitvive]

Hi mates,

I've an issue with the standby function of the LG OLED77C19LA from a colleague.

Device
Model: LG OLED77C19LA

PSU
PCB: EAX68999802
LG P/N: EAY65689422

He described the problem to me as follows: The device can be switched on normally and does not cause any problems.
As soon as you switch it to standby, it stays on for about 3 minutes and then switches off. It can then no longer be switched on.
If you then disconnect the power using the plug or a power switch, the TV switches on normally.
Could this be a defective electrolytic capacitor from the fault pattern?

As I have read in some places on the net that it is often related to the PSU PCB, I have now received this from him and have it here.

The power supply is huge and I have hardly any experience with it... but now I want to use it to learn a few things.

I hope you can help me to find the error and eliminate it. How to proceed etc., that would be great

Best

Sebastian

[Diah]

there are no fault unless if he or any other do before work repair on PSU... its pixel refresh timing., send IN_STOP command via service Rc or APK or DIY wave files could bring the timing Bach as it should... in case the first point i mentioned not account.

[Bitvive]

there are no fault unless if he or any other do before work repair on PSU... its pixel refresh timing., send IN_STOP command via service Rc or APK or DIY wave files could bring the timing Bach as it should... in case the first point i mentioned not account.

I don't quite understand? So I hope I've explained correctly that the TV itself runs for hours at a time.

[Diah]

I don't quite understand? So I hope I've explained correctly that the TV itself runs for hours at a time.

google after IN_STOP command for LG and pixel pixel refresh for LG OLED, or search this forum we did explain it manyr of times

[Bitvive]

google after IN_STOP command for LG and pixel pixel refresh for LG OLED, or search this forum we did explain it manyr of times

Hi Diah,

I have now spent some time googling and have also read up here in the forum. Now I think I understand the In_Stop command. This simply resets the TV to the model-specific factory calibrations?

But I can't find anything about my error anywhere. As I said, the TV runs without any problems and goes into standby after being switched off manually. After 3 minutes the standby goes off and the TV is dead. If you disconnect the cable from the socket and then plug it back in, it works normally until you switch it to standby manually.

Maybe I have not understood something of your suggested solution?

So I understand that you are assuming that there is an issue in the OS?

[Diah]

So I understand that you are assuming that there is an issue in the OS?

first of all you should do In_STOP. if the issue after that no change or get better... then we talk on HW

[Bitvive]

first of all you should do In_STOP. if the issue after that no change or get better... then we talk on HW

I understand the process of first ruling something out with In_stop. However, are there any useful measurements I can make on the PSU board to rule out errors on it? My colleague won't be back for another 2 weeks.

[Diah]

I understand the process of first ruling something out with In_stop. However, are there any useful measurements I can make on the PSU board to rule out errors on it? My colleague won't be back for another 2 weeks.

any measurements on PSU or other parts are useless before sending IN_STOP. LG platform are digital controlled vie MICOM which it depending on IO controlled via OS. bringing OS to first state are the first things need to do. or you want to missing with yours friends set..!!

[EazyBone]

Put board back in, leave it off stand turn TV on. Use multimeter on the main caps. Hit power, check the readings, see if voltage starts dropping. Or on the 12v/24 line (I can't read the picture) that connects to the main board. See where the voltage is when you turn the TV in die the first time and where it drops to when the TV light dies. Measure before TV on first time, while on, and once off for that 3 minutes. It should always be a constant voltage . That's what I would check. Beyond that if it ALL stays constant I would assume it's probably fine. Would also do as diah said but I would try this since you got 5 minutes

[Bitvive]

All right, let's do it like this. We'll try the IN_Stop command and then we'll see. Do you have a simple, clear guide for the IN_Stop without Service Remote that works for this LG model?

[Davi.p]

I see no problems (never seen this board anyway) in testing the PSB in standby and full ON modes, simply provide the turn on commands (are you able?) and see if the defects are present, for my experience i see no way how it can be the PSB, is trust more a MB defect, maybe bad standby processor if present separately, the sad part i never seen one that shared info or files about those chips.. bye..

[Bitvive]

Hi together,

now the update.. As I thought, the IN_STOP command didn't help at all. The IN_STOP command is sent -> the TV wants to restart -> and no longer switches on due to the standby problem.

The TV switches itself off or tries to restart, but does not manage to wake up the standby, as the lamp stays on for a maximum of 3 seconds.

I guess there are problems with the standby voltage on the PSU or the T-CON board? There must be a component responsible for this. Since apparently the voltage cannot be maintained. hmm, some kind of buffer capacitor?

[Davi.p]

The standby voltage is normally not present only in st.by state, but always, this rail can be tested easily with a resistor, load it with 0,5A around (5v/0,5A=10ohm/5w), if the voltage remains, the resistor heats, then ok, but i know it's not power supply problem, it is one of these: bad standby software, bad BGA balls on cpu or ram..

[Bitvive]

The standby voltage is normally not present only in st.by state, but always, this rail can be tested easily with a resistor, load it with 0,5A around (5v/0,5A=10ohm/5w), if the voltage remains, the resistor heats, then ok, but i know it's not power supply problem, it is one of these: bad standby software, bad BGA balls on cpu or ram..

So first check the standby voltage to see if it is present everywhere? Unfortunately I can't find any schematics for this model. Up to from the PSU is still visible on the plug.

Ouh ouh, very bad.. Do you mean that it is more likely to be CPU or RAM? Then it must be bad solder or oxidation on the balls? Do you think a reball attempt would be successful?

Edit:
Whereby the TV runs for hours without any problems - until it is switched to standby. Are you really thinking of problems with the RAM or CPU? Then normal operation should not work until the standby state.

[Diah]

Hi together,

now the update.. As I thought, the IN_STOP command didn't help at all. The IN_STOP command is sent -> the TV wants to restart -> and no longer switches on due to the standby problem.

The TV switches itself off or tries to restart, but does not manage to wake up the standby, as the lamp stays on for a maximum of 3 seconds.

I guess there are problems with the standby voltage on the PSU or the T-CON board? There must be a component responsible for this. Since apparently the voltage cannot be maintained. hmm, some kind of buffer capacitor?

disconnect only the lower LVDS ( you have 2 the lower which are close to screen ) between T-CON and mainboards then start the TV.... the screen will remain black but the sign of running you will see the audio optic port on the Main board will lit red and remain on.

[Davi.p]

1) i mean isolate the power supply and load only the standby 5v
2) The main processor could have an integrated standby MPU, with separate contact balls, their contact balls could be bad, if the standby mpu is external, it could be the cause, i need EAX code of the main board.. for the RAM discourse, it could be possibile that the standby software, to be more fast, could be copied in a certain area of the RAM, especially if there is no SPI flash, there could be a bad RAM or its balls for that..

The economical aspect of doing a reball of such an amount of chips is out of my knowledge, especially if based on my examination, i'm still a passionate hobbist.. even if with years of readings..

[Diah]

hahahaha MPU... LOL this is TV not PC... learn about the different between PC CPU and TV SoC

[Bitvive]

Resetting via the stop function did not help. I think there seems to be a fault on the power supply PCB?

[Davi.p]

So can you post the EBT/EBR codes of main board? I think you are not following well at least my posts, or your effort is not enough, with theese today's beasts of technologies you can't approach them with such no knowledge, i' m sorry, if you do things ok, otherwise, it's not a cheap tv, aren"t there service centers?

[Diah]

Resetting via the stop function did not help. I think there seems to be a fault on the power supply PCB?

now we can talking on HW.... take the PSU alone on the table.. just plug it in wall and write the V you have on the socket with pin name.. which it goes to MB