LG/Optica 7074c / 42" SmartTV

[badcaphunter]

Hello BadCaps Community my friend got this TV through Buy As You View, about 2 weeks ago the bottom half of the screen started going dark, i have reset it and checked energy saving and brightness settings but the problem still persists, when i turn the TV on it is fine but after 3-4 seconds the shadow appears. I have opened the set up and checked all the boards and reseated every cable. i suspect this is a panel issue. Any help would be appreciated.

He has had the tv just over 18 months and his warranty has expired.

[Andrew F. Ali]

Re: LG/Optica 7074c / 42" SmartTV

Looks like bad backlights to me.

[ReeceyBurger123]

Re: LG/Optica 7074c / 42" SmartTV

Wheres Lg come from as well ? Nothing Lg about this I dont think. Also yes I agree with Andy Leds are out. Please post images of the boards.

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Its an LG panel, the TV comes on full brightness when turned on from cold but 3-4 seconds then it goes dark, i will post pics soon

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Sorry about the pics, i will post better ones tomorow

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Hope these help

[budm]

Re: LG/Optica 7074c / 42" SmartTV

https://www.badcaps.net/forum/attach...2&d=1471877937

Check the DCV on the test points VR 1~VR 6 with ref. to the chassis GND.

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Thanks Budm, when taking the readings the 2 coils on the inverter board were pretty hot, not sure if that is normal.

VR1 - 0.8v
VR2 - 0.7v
VR3 - 0.9v
VR4 - 1.1v
VR5 - 1.1v
VR6 - 1.0v

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

These are the LED strips that this panel uses

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

The bottom LED's are failing but the top ones are still working, i took the screen apart and 1 of the strips is dying but is this defective LED's or something else?

[budm]

Re: LG/Optica 7074c / 42" SmartTV

The reason that most of the TV with LED backlights have failed LEDs is due to the LEDs are being driven too hard close to or at the maximum spec with no regard to the ambient temperature so they failed. When you are done fixing the TV you should turn down the backlights level to as low as you can to extend the life of the LEDs.
I am surprised that the protection circuit did not kick in due to bad LEDs, may be they just do not care.

This is the Notes from LG LED spec:
Operating the LED beyond the listed maximum ratings may affect device reliability and cause permanent damage.
These or any other conditions beyond those indicated under recommended operating conditions are not implied.
The exposure to the absolute maximum rated conditions may affect device reliability.

Example of bad design in LG:
https://www.badcaps.net/forum/showthread.php?t=54197

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

I thought the TV had 2 banks of LED's but its only 1 strip with 60 LED's, they all light up from cold then most of them die and a few stay lit. as u can see in the picture 8 are lit then 1 is dead then the 10th 1 lit.

I have tested each individual LED with a battery and they all seem to work fine.

Thanks for your help

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

It looks like LG are not renowned for there backlights :o

Could a problem with the inverter cause these symptoms or would it be worth buying a new LED strip and hoping for the best?

[budm]

Re: LG/Optica 7074c / 42" SmartTV

Each bank has three set of LED string, that why you have VR1~VR6.

[Diah]

Re: LG/Optica 7074c / 42" SmartTV

from yours photos i can say the LED are less than 60 on one strips as there are 3 groups of LEDs on each strip please check again, this LEd edge one 6 Volts, its crazy to be if one groups will be 20 LEDs

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Hey Diah, i have double checked and there is 60 LEDs on the strip, it is numbered in 5s up to 60

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

Pics

[Diah]

Re: LG/Optica 7074c / 42" SmartTV

dear friends,, yours TV set look like DIY TV , i will never believe on what printed on.. when you have booting firmware on 2GB SD card, you would believe on what printed ? lol check with finger 1.2.3 .4 sorry mat

[Diah]

Re: LG/Optica 7074c / 42" SmartTV

it would be nice if you dump the total of SD card as zip and posted here... very interesting one.. did yours SET android firmware?

[badcaphunter]

Re: LG/Optica 7074c / 42" SmartTV

No but i think this was TV on finance so they could disable the TV remotely, it can be flashed to android if you know how, it still works without the sd card.