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Crumbtrail TV Forums: TV Equipment: TV Repair Forum:
LG 42LB580V LEDs flash at switch on

 

 


CaptainB
New User

Aug 2, 2020, 8:16 PM

Post #1 of 9 (265 views)
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LG 42LB580V LEDs flash at switch on Can't Post

Hi All,
I've done a bit of reading about this and tried to find the solution but I've drawn a blank so far.

My LG 42LB580V will flash the backlights for about a quarter of a second when I switch the TV on, then they go out. I can see the image with a light etc so I think the main board is OK.

I checked the power board and found that the voltage drops from ~200v to about 3v very quickly after switching on. Easy, just replace the power board I thought. Did that and now have a steady 104v on the output with the LEDs connected and the tv switched on. The symptoms are still identical though.

Is it likely there's a LED issue? I ruled that out as they flash briefly but what am I missing?

Thanks in advance for any help.



jts1957
Veteran


Aug 4, 2020, 12:14 PM

Post #2 of 9 (244 views)
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Re: [CaptainB] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post


Quote
Is it likely there's a LED issue? I ruled that out as they flash briefly but what am I missing?


Unless you have observed each and every one of the backlight LEDs lighting to the same intensity ...\

https://www.youtube.com/watch?v=KsVkdY2vVGw
https://www.youtube.com/watch?v=h5Zyqowl6zg


-------------------------
Location: Far, Far Away


CaptainB
New User

Aug 5, 2020, 8:29 AM

Post #3 of 9 (231 views)
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Re: [jts1957] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post


In Reply To

Quote
Is it likely there's a LED issue? I ruled that out as they flash briefly but what am I missing?

Unless you have observed each and every one of the backlight LEDs lighting to the same intensity ...\

https://www.youtube.com/watch?v=KsVkdY2vVGw
https://www.youtube.com/watch?v=h5Zyqowl6zg



Thanks for that. The Youtube videos were very enlightening Laugh

I had assumed that the LED strips would fail as a unit rather than lose individual LEDs. With the image being evenly lit I thought that the LEDs were all functioning. So I stripped the TV down completely last night and tested the LED strips. Sure enought there were 4 LEDs that were dead.

Just deciding whether to buy the SMDs and try to solder them on, or just go the easy route and buy the strips.

Do the LEDs die from overheating? Everywhere I see LEDs being described with 100,000 hour lifespan, I'd be amazed if these have done 1000 hours.


jts1957
Veteran


Aug 5, 2020, 11:56 AM

Post #4 of 9 (230 views)
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Re: [CaptainB] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post

The automakers forget to tell you that your new car won't last nearly as long if you insist on driving with the gas pedal held to the floor at all times. Wink


-------------------------
Location: Far, Far Away


CaptainB
New User

Aug 5, 2020, 12:08 PM

Post #5 of 9 (228 views)
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Re: [jts1957] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post


In Reply To
The automakers forget to tell you that your new car won't last nearly as long if you insist on driving with the gas pedal held to the floor at all times. Wink


Aah, I see. So running the backlight high presumably generates more heat and it's the heat that kills 'em?


jts1957
Veteran


Aug 5, 2020, 12:36 PM

Post #6 of 9 (226 views)
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Re: [CaptainB] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post

Bonfire inside an automobile never was a good idea. Crazy


-------------------------
Location: Far, Far Away


CaptainB
New User

Aug 5, 2020, 3:56 PM

Post #7 of 9 (221 views)
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Re: [jts1957] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post


In Reply To
Bonfire inside an automobile never was a good idea. Crazy


LaughLaughLaugh


jts1957
Veteran


Aug 5, 2020, 4:32 PM

Post #8 of 9 (220 views)
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Re: [CaptainB] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post

You DO realize that there is a Reply button at top right corner of each post that won't repeat prior post (In reply to).Unimpressed


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Location: Far, Far Away


CaptainB
New User

Aug 6, 2020, 8:40 AM

Post #9 of 9 (207 views)
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Re: [jts1957] LG 42LB580V LEDs flash at switch on [In reply to] Can't Post

Decided to order the strips of LEDs this time. I just don't have the time (or the proper kit) for replacing SMDs at the moment. Will update when I have fitted and tested them.

 
 
 


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