LG 49UF6409 No Picture, Backlight & Sound working

[hendue]

Hello everyone,

so my TV recently decided to stop working.

At first, it sometimes showed just one color on screen after switching it on, but as far I remeber the menu still worked.
Now theres no way to get it to that anymore, just a blank screen :/

I've already tested unplugging either the right or left cable from the TCon to the panel, but neither halves of the TV had a picture (see attached files). The white half is always on the unplugged side, the other side stays blank.
With the right cable unplugged, the right side faded to grey after leaving it plugged in for a while.
Theres atleast the correct voltage appearing at both sides of the TCon's fuse.
Does anyone of you has an idea, which part of the TV might be the issue?

Thanks in advance

[nomoresonys]

Might be a tcon issue, make sure the ribbon cables from tcon to driver boards are not damaged, can clean the ends with iso alcohol, some use a pencil eraser, not too vigorously they can be fragile, make sure the cable from mainboard to tcon is secure and clean also.

[hendue]

Thanks a lot for your reply, I'll clean the cables up and give an update later on

[hendue]

I checked & cleaned all of the cables now, but still yield the same results.
Additionally, I've measured the voltages for all points, but I'm not quite sure how to interpret them:

Fuse 13.16
VDD 15.78
VCore 1.2
VCC18 1.8
Pwm tout4 3.3
Adim on 0
Vcc 3.3
Vin 13.15
Hvdd 7.68
Vgl1 -7.02
Vgl2 0
E0 0
Gclk 1.2
Gst 0.015
Mclk 0.074
Vgh_odd -7
Vgh_even -7
Vst -7
Vcom2 5.54
Vcomrfb 5.54
V1 15.37
V5 11.78
V9 8
V10 7.39
V14 3.72
V18 0.4
CLK1-8 all 7.77

Is there anything else I can test?

[EazyBone]

Likely the panel went to shit. Someone cleaning the screen recently? Google fixing TV with tape and try that. If it works it's likely the panel. but yes maybe small chance is tcon

[hendue]

There was no cleaning recently and no Otter water damage. I already checked the resistors on the LCD Board for shortages.
Taping the Board didnt seem to have an effect either.
So it's not the panel but TCon or Mainboard?

[EazyBone]

That doesn't eliminate the panel. It's still likely the panel. We don't have pics of the rest of the board. Generally you can disconnect the main board from power board. Then disconnect the main board to TCON board. Then you jump 3.3stby on PSU with TCON on and Blon and pw on. Plug it in andb. This will turn on BL and potentially cycle a image on the screen RGB colors

[Storyteller12]

I’m almost positive these “UF” series TVs had a problem with the main board. I think it’s the processor if I’m not mistaken and a reflow will not work.

[lotas]

Your VGH signal is low, it should be +27v.

[hendue]

That doesn't eliminate the panel. It's still likely the panel. We don't have pics of the rest of the board. Generally you can disconnect the main board from power board. Then disconnect the main board to TCON board. Then you jump 3.3stby on PSU with TCON on and Blon and pw on. Plug it in andb. This will turn on BL and potentially cycle a image on the screen RGB colors

Of which board do you Need more pictures?
I'm not quite sure whether I get your other instructions right. So I'm supposed to disconnect the cable between Mainboard & PSU. If I do so, the backlight stays off for whatever reason. Additionally, the LVDS or the power cable between Mainboard & TCon needs to be unplugged?
And after unplugging the cables, the TV needs to be plugged in and is supposed to show the colored pictures?

[hendue]

I’m almost positive these “UF” series TVs had a problem with the main board. I think it’s the processor if I’m not mistaken and a reflow will not work.

That's sad to hear. But thanks a lot for your information!

[EazyBone]

Ahh now that we have the picture the test I told you will not work. Sometimes sonys have direct power to TCON from PSU. This doesn't. Not sure where else to direct you here. Some other more experienced people may have suggests

[hendue]

Alright. I just ordered a new TCon & Mainboard and keep you updated, if one of these will be able to bring it back to life.

[EazyBone]

Yea hopefully. Give us the update I'm curious

[hendue]

The spare parts just arrived and after replacing the mainboard, the TV is working again!
Thank y'all for helping me out

[nomoresonys]

I’m almost positive these “UF” series TVs had a problem with the main board. I think it’s the processor if I’m not mistaken and a reflow will not work.

Good call.

[EazyBone]

Yea nice call. Good to know