LG 70LB7100 no backlight after 2-5 min

[DXseekerMO]

Re: LG 70LB7100 no backlight after 2-5 min

I think there are 8 rows of LED strips in this TV. There's 24 total pieces to the LED array divided by three in one row equals 8 rows total

[zomi]

Re: LG 70LB7100 no backlight after 2-5 min

https://www.aliexpress.com/item/New-...875904086.html

I would just get that

[DXseekerMO]

Re: LG 70LB7100 no backlight after 2-5 min

https://www.aliexpress.com/item/New-...875904086.html

I would just get that

That is nearly half of what ShopJimmy wants for a set of those, great find! My only question would be the quality of the strips, but if they are up to par then that is a great deal!

[floki]

Re: LG 70LB7100 no backlight after 2-5 min

https://www.aliexpress.com/item/New-...875904086.html

I would just get that

Thank you so much!

[floki]

Re: LG 70LB7100 no backlight after 2-5 min

I think there are 8 rows of LED strips in this TV. There's 24 total pieces to the LED array divided by three in one row equals 8 rows total

Gotcha. I'll probably go ahead and take the TV apart first to verify before ordering. I got the TV for free from a buddy, so spending a $100 or so to possibly repair is a risk i'm willing to take.

[DXseekerMO]

Re: LG 70LB7100 no backlight after 2-5 min

Have you considered getting a practice TV?

[bult]

Re: LG 70LB7100 no backlight after 2-5 min

I ended upp taking the panel off. The problem was with some of the LED´s. Some were shorted others were open. It was a pretty easy job but time consuming since I ended up testing every LED separately. Gluing the lenses back took some time... And yes, my garage is a mess...

[shafercomputers]

Re: LG 70LB7100 no backlight after 2-5 min

Just some info from a tv repair man. I've worked on this set once before issue was intermittent loss of backlights(had bad backlights) no surprise with tvs nowadays but after replacing all the backlights it still had the same issue. Almost never have a set with backlight issues that weren't in the strips or the power supply. Replaced the power supply as well same issues. Customer was getting impatient by now so we called it quits. So I ended up selling the circuit boards on Ebay. After selling the Main board got a message from the buyer saying that their set that was having different issues all together now had a new symptom.. Intermittent loss of backlights. So apparently the main board on this set has a lot of control over backlight function along with the set having just general led failure as well. Just had the same model brought in today too with same symptoms I'll give ya an update on what I find.

[shafercomputers]

Re: LG 70LB7100 no backlight after 2-5 min

Went ahead and replaced Main Board as it's main IC was running 140F-150F. Also backlights tested fine on this specific set. Since this set has no ventilation I installed a pc fan and drilled some holes for air intake and out. Main IC on new Main Board was running at around 125-130F which is around normal. Set has been back to customer for almost a month now with no issues. So to summarize this set's main board seems to overheat and turn the backlights off at least on the past two I've worked on.

[KPGipson]

Re: LG 70LB7100 no backlight after 2-5 min

Hi- I have a 70LB7100 with backlight issues. I received a used unit and it would play for a couple of hours then the backlight would turn off (brightness at 100%). There was still sound and video. If I turned the TV off then back on it would come on and the backlight would turn on for a couple of minutes then off. If I turned the brightness down to 80% the backlight would stay on for much longer.

Sounds like a thermal issue.

Then I removed the back cover of the TV and turned it on. The backlight seemed to go off if I tried to lift the panel or move it a small amount. Now, the backlight goes off ~ 7 secs after turning the set on and the red LED on the power supply blinks 4 times repetitively.

Now since the backlight is only on few a few seconds I can't turn the brightness down or do a factory reset. When the TV was working the display looked great but I did not test it with a full white screen to see if any LEDs are dim or completely out.

Any suggestions? Thanks.

[KPGipson]

Re: LG 70LB7100 no backlight after 2-5 min

Another note: I disconnected the LED cables from the power supply and powered the TV up. The red LED did not come on. I turned the unit off, reconnected the cables, and powered it up. It acted as before with the red LED blinking.

[b0ba]

Re: LG 70LB7100 no backlight after 2-5 min

-- del --

[nomoresonys]

Re: LG 70LB7100 no backlight after 2-5 min

This right here is most likely pointing to bad backlights: Quote " If I turned the brightness down to 80% the backlight would stay on for much longer."