LG 49UF770v No display

[MattM]

I have a LG 49UF770V UHD LED TV here.

The set fails to power up with three blinks on the led on the front of the set.

I thought it was the psu so purchased a replacement from a recycler but this is displaying the same fault.

Looking at the psu the LED on the psu (not the TV) is blinking five times.

I haven't been able to get hold of the service manual.

Has anyone got any suggestions please?

Thank you very much

[Andrew F. Ali]

Re: LG 49UF770v No display

Have a look at the T-CON Bd. There is a little fuse there. Check the fuse for continuity. Is there an LED on the Main bd. as well?

[MattM]

Re: LG 49UF770v No display

Thank you will try that now. There is no LED on the mainboard.

[MattM]

Re: LG 49UF770v No display

Fuse on the T-Con is fine. I'm thinking it must be the mainboard

[Andrew F. Ali]

Re: LG 49UF770v No display

Yes I agree. I think it is a Main Bd. failure.

[MattM]

Re: LG 49UF770v No display

Well the update is I replaced the mainboard today and it is powering up now and the LED's are lit but there is no display just a white screen. The led on the front panel is flashing three times. There is no more flashing of the psu led on the psu. I am bit stumped as to where to go next. Has anyone got any ideas please? Thank you

[MattM]

Re: LG 49UF770v No display

I have now replaced the T-Con as well but that did not resolve the problem. I am wondering if the replacement mainboard is defective. I cannot seem to work out what the three flashes on the front LED means and whether that might help with diagnostics. I am really struggling with this and would be grateful of any advice. Thank you

[budm]

Re: LG 49UF770v No display

Are you getting 12VDC at both ends of the SMD fuse on the T-CON board with ref. to the chassis GND?

[MattM]

Re: LG 49UF770v No display

Hi thanks for your help with this, yes I am getting 12VDC at both ends. Thank you

[MattM]

Re: LG 49UF770v No display

Removing each side on the t-con brings a bright white display to the lit side. Returning them both brings the soft lit display I already had. Any further help would be greatly appreciated.

[Hamie]

Re: LG 49UF770v No display

Meh more UF main board junk

[MattM]

Re: LG 49UF770v No display

So do we think the main board is the problem and maybe the one I bought is also faulty? Thank you

[MattM]

Re: LG 49UF770v No display

I can send the original main board for repair, wondering if that’s the way to go? Thank you

[MattM]

Re: LG 49UF770v No display

I was able to repair the original main board and when re-installed the TV came back to life. The replacement was clearly faulty. Thanks for tips

[MattM]

Re: LG 49UF770v No display

The original mainboard has failed again so I have bought a replacement. When I installed this I get a blue screen which is what I got when I installed the previous replacement which I believe to be faulty. The main board is a perfect match but is for the 55uf770v model. I presume they used that one in the 49uf770v with the correct panel being selected in the engineering menu. Does anyone know how to access the engineering menu or reset the TV completely - possibly the eeprom? Thank you

[dick_barton]

Re: LG 49UF770v No display

What was the repair on the original main board and is the same failure.?

[MattM]

Re: LG 49UF770v No display

Hi, the repair on the original board was re-flowing but it lasted a matter of hours and a permanent solution is required. It is not the same failure. I am pretty convinced that the new board is working fine but the problem is that it needs to be configured for my panel - it was pulled from a 55uf770v and mine is the 49uf770v. I just can't work out how I can reset it. Of course I could be completely wrong. Thank you

[dick_barton]

Re: LG 49UF770v No display

Have you tried https://factory-reset.com/wiki/LG_Service_Menu

[MattM]

Re: LG 49UF770v No display

Thank you, I have had a go with these without success but I have the magic remote which doesn't have the same keys so I am not sure if I am doing it right. Thanks again

[MattM]

Re: LG 49UF770v No display

Update - it has proved impossible to get the service menu to display. I am wondering if it is simply impossible to change the panel. The only other option would be to remove the eeprom from the faulty board and put it in the good board. Has anyone done this or got any ideas please?