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Lg 50la6205-ua - no led back light    
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Wendell1980



Joined: 30 Dec 2007
Posts: 74
Location: Cambridge, Ontario, Canada

PostPosted: Tue Mar 03, 2015 6:13 pm    Post subject: Lg 50la6205-ua - no led back light Reply with quote

Lg smart tv model 50la6205-ua set has audio and has a picture if you shine a flashlight at the screen, I already pulled the inverter board for the led backlights no bad caps that I can see, at powerup the backlight does come on for 2 seconds and go out again
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brianm



Joined: 24 Sep 2015
Posts: 2

PostPosted: Thu Sep 24, 2015 9:24 pm    Post subject: similar problem Reply with quote

wondering if resolved your problem....I have the 50la6205 TV and the back light is not working. Would someone have the service manual? where can I get the back light board? thank you
JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Fri Sep 25, 2015 12:11 am    Post subject: Reply with quote

http://www.electronica-pt.com/esquema/func-fileinfo/25021/ MAY be close enough as it supposedly is the same chassis. Compare board numbers to be certain. Or not as it appears to be a stripped down manual. Google your LCD panel number for datasheet.
Many manufacturers have their TVs set-up to produce the best picture for the average viewer. This usually means that customer controls regarding back lighting are set to 100% when they are shipped to distributors/arrive at the customers homes. This has the ?desired? effect of shortening the sets life. A bit like running a cars engine at maximum RPMs for extended periods of time.
Even one bad LED can cause the series connected string(s) not to stay lit. So don't forget to check for one (or more) dead LEDs.
brianm



Joined: 24 Sep 2015
Posts: 2

PostPosted: Wed Oct 28, 2015 1:01 pm    Post subject: update. Reply with quote

The service manual was not much help.

I have determined that it has to be the led back lights that are going out.

The power supply board with built in inverter has a plug that is labeled led + and led - There are 2 pairs of wires going inside the TV from this connector. I have found that the led + pins have about 88 volts DC on them both with the leds plugged in and without them plugged in.

So it has to be the leds themselves.....so now what. I can buy the leds BUT how do I get in there to replace them.

Any videos or step by step instructions on how to proceed? Do you have a personal experience that will help me.


Thanks so much.
JTS1957



Joined: 21 Jan 2009
Posts: 2286
Location: Far, Far Away

PostPosted: Wed Oct 28, 2015 4:08 pm    Post subject: Reply with quote

Manufacturer wants you to throw away. At best will supply panel for a limited time, usually at a out-of-this-world price.

Each panel requires some CAREFUL disassembly to get to the innards. Some make it easy, some hard. Will also depend on if it is edge lite or array lit:
http://s772.photobucket.com/user/8mile13/media/led_and_lcd_backlighting_zps26840d5f.jpg.html

Each bulb can be tested using two AA or C or D wired in series and applied to LED with the correct polarity.
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