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Old 11-05-2018, 09:00 AM   #21
floki
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Default Re: LG 70LB7100 no backlight after 2-5 min

Anyone figure anything out with this? I was given this TV for free from a guy and it's doing this exact same thing - backlight stays on for about 45 seconds, then shuts off. Sound continues to work and everything. Replaced the main board, and that didn't fix anything. I'm considering replacing all LED's, but was hoping someone would have confirmation that that's the issue before spending the time and money
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Old 11-05-2018, 10:49 AM   #22
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Default Re: LG 70LB7100 no backlight after 2-5 min

Did you try turning down the backlights level as suggested to see if it will stay on longer?
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Inverter testing using old CFL:
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Old 11-05-2018, 12:05 PM   #23
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Did you try turning down the backlights level as suggested to see if it will stay on longer?
No, i'll try that tonight and post results. Thank you so much for the reply!
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Old 11-06-2018, 06:44 AM   #24
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Default Re: LG 70LB7100 no backlight after 2-5 min

So unfortunately I don't have the remote for this TV, and it doesn't appear that the little joystick button on the bottom of the TV will adjust brightness.....I'll have to look around for a remote for this model TV so I can try the brightness adjustment. With my TV, it always blacks out at the same time, about 30 seconds without fail, it never changes. It's almost like it might be the TCON board, since when the monitor is lit there is no flickering or dead spots, it looks perfect, then 30 seconds or so, it blacks.
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Old 11-06-2018, 06:54 AM   #25
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Default Re: LG 70LB7100 no backlight after 2-5 min

disconnect the cables from the tcon to panel, one at a time to see if it changes anything, go from there.
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Old 11-06-2018, 03:01 PM   #26
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Default Re: LG 70LB7100 no backlight after 2-5 min

If this model has 2 strips joined in middle, I would hardwire every one.
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Old 11-06-2018, 03:16 PM   #27
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Default Re: LG 70LB7100 no backlight after 2-5 min

Biggest set I have successfully replaced LED arrays on is a 52". That was very trickey and I made a ramp and blocked it up to the right level next to tv on another bench. Anything any bigger is going to be impossible to support the lcd screen without cracks.
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Old 11-06-2018, 03:33 PM   #28
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Default Re: LG 70LB7100 no backlight after 2-5 min

use suctions cups
lift the screen using a second person and place on a table while u work on the set

https://www.youtube.com/watch?v=KTPJxkzkaSs&t=689s
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Old 12-03-2018, 08:39 PM   #29
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Originally Posted by budwich View Post
disconnect the cables from the tcon to panel, one at a time to see if it changes anything, go from there.
i'll try this hopefully tonight. thank you. i got a remote on ebay but the display goes out too quickly for me to be able to see what i'm doing to dim the display down.....
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Old 12-03-2018, 08:55 PM   #30
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Originally Posted by floki View Post
i'll try this hopefully tonight. thank you. i got a remote on ebay but the display goes out too quickly for me to be able to see what i'm doing to dim the display down.....
well, i unplugged the ribbon cables going from the tcon to what i believe is called the main board, and the screen has now been on for like 10 minutes...which is WAY longer than ever before. it used to go out in like 5 - 10 seconds maximum. could it be there was a bad connection? gonna let it sit for a while with the screen on and see. i was able to then change the display setting to maximum power save, which dimmed the screen considerably, so not sure if that is helping or not...
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Old 12-03-2018, 09:18 PM   #31
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Default Re: LG 70LB7100 no backlight after 2-5 min

Feel for warmth around the frame on right or left might be driver tab. This tv may have the tabs built into the main panel tab bonds so feel what ever side the tcon is on . Also try shining a light to see if you see anything and this will determine if its a back light.

Last edited by bman4; 12-03-2018 at 09:19 PM..
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Old 12-03-2018, 09:43 PM   #32
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Originally Posted by bman4 View Post
Feel for warmth around the frame on right or left might be driver tab. This tv may have the tabs built into the main panel tab bonds so feel what ever side the tcon is on . Also try shining a light to see if you see anything and this will determine if its a back light.
yea, it went out after like 30 minutes. no warmth felt at all, all sides seem cooler than room temperature. i shined a flashlight on the screen while a movie was playing and i COULD see the picture in the backround.

Must be the backlight then, eh?
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Old 12-03-2018, 09:46 PM   #33
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Default Re: LG 70LB7100 no backlight after 2-5 min

Well, did you try turning down the backlights level (not brightness) to as low as possible as I suggested?
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Old 12-03-2018, 09:55 PM   #34
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Originally Posted by budm View Post
Well, did you try turning down the backlights level (not brightness) to as low as possible as I suggested?
The only thing I can find on adjusting brightness on this model is just adjusting the picture to energy saving mode, which I did and the brightness dimmed way down. i did that after disconnecting those two cables I mentioned earlier. after disconnecting the cables and reconnecting the leds stayed on for long enough for me to adjust that setting, and that's when it stayed on for like 30 minutes (which is WAYYYY longer than it had stayed on before)
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Old 12-03-2018, 10:11 PM   #35
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Default Re: LG 70LB7100 no backlight after 2-5 min

Sure sounds like a problem in the LED string to me, like something getting up to operating temperature and going open circuit.
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Old 12-03-2018, 10:22 PM   #36
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Default Re: LG 70LB7100 no backlight after 2-5 min

Your LEDs are bad.
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Old 12-03-2018, 10:25 PM   #37
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Your LEDs are bad.
can you guys recommend a place where I can get replacements? is that a super difficult fix? I've heard it can be tedious handling the screen itself to gain access to the leds
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Old 12-03-2018, 10:45 PM   #38
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Default Re: LG 70LB7100 no backlight after 2-5 min

On a screen that size you're going to need help, steady hands and suction cups. If you've never pulled/handled an LCD Display I STRONGLY recommend you go to a recycle center and see if they have a similar TV with a good display that size and practice on it first. If you're unfamiliar with how a screen that size acts and flexes when lifted out you will surely break it.

This is the listing on those LED strips, one row only and are the only ones available right now from ShopJimmy.com. The full set is out of stock.

https://www.shopjimmy.com/lg-innotek...w-3-strips.htm
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Old 12-04-2018, 07:06 AM   #39
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Default Re: LG 70LB7100 no backlight after 2-5 min

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Originally Posted by DXseekerMO View Post
On a screen that size you're going to need help, steady hands and suction cups. If you've never pulled/handled an LCD Display I STRONGLY recommend you go to a recycle center and see if they have a similar TV with a good display that size and practice on it first. If you're unfamiliar with how a screen that size acts and flexes when lifted out you will surely break it.

This is the listing on those LED strips, one row only and are the only ones available right now from ShopJimmy.com. The full set is out of stock.

https://www.shopjimmy.com/lg-innotek...w-3-strips.htm
Thanks much for your help. Do you happen to know how many rows this TV takes? I haven't taken it all the way apart yet.
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Old 12-04-2018, 07:19 AM   #40
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Default Re: LG 70LB7100 no backlight after 2-5 min

I wanna say there are 3 rows, but not sure...in other words I think i'd need to order 3 of these strips
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