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Crumbtrail TV Forums: TV Equipment: LCD TV Forum:
LG LCD no backlight

 

 


85XJS
New User

May 30, 2016, 8:57 PM

Post #1 of 8 (1999 views)
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LG LCD no backlight Can't Post

LG 47LN5790 Power on and the tv backlight flashes then goes dark. Flash light test shows video image present also setting screen can be brought up. Also audio not present. Power supply shows only millivolts on the output test points. Put in another power supply and same thing. Where should I look for problem? Perhaps main board? On t-con board?



jts1957
Veteran


May 30, 2016, 9:09 PM

Post #2 of 8 (1998 views)
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Re: [85XJS] LG LCD no backlight [In reply to] Can't Post

The Panel.

Which input are you using that sound is NOT present?


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Location: Far, Far Away


85XJS
New User

May 30, 2016, 9:32 PM

Post #3 of 8 (1995 views)
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Re: [jts1957] LG LCD no backlight [In reply to] Can't Post

Just using the coax from dvr


jts1957
Veteran


May 30, 2016, 10:38 PM

Post #4 of 8 (1991 views)
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Re: [85XJS] LG LCD no backlight [In reply to] Can't Post

Try a couple of other inputs. Sets with dead LEDs that have video and Menus/OSD will usually have audio present too.


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Location: Far, Far Away


85XJS
New User

May 30, 2016, 11:46 PM

Post #5 of 8 (1986 views)
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Re: [jts1957] LG LCD no backlight [In reply to] Can't Post

Does the main board control the power supply and that is why I am not getting any voltage out to the LEDs


jts1957
Veteran


May 31, 2016, 12:38 AM

Post #6 of 8 (1985 views)
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Re: [85XJS] LG LCD no backlight [In reply to] Can't Post

More like the manufacturer shipped the TV with the LED intensity at 100% and nobody thought to turn it down, significantly shortening the life of one (or more) LED back light bulbs inside the panel.


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Location: Far, Far Away


85XJS
New User

May 31, 2016, 1:13 AM

Post #7 of 8 (1982 views)
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Re: [jts1957] LG LCD no backlight [In reply to] Can't Post

I will check the LEDs next. But I am still wondering why there is no voltage at the power supply test points with the LED plug disconnected.


jts1957
Veteran


May 31, 2016, 9:09 AM

Post #8 of 8 (1980 views)
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Re: [85XJS] LG LCD no backlight [In reply to] Can't Post

From Shop Jimmy site:
PLEASE NOTE: Models that use this power supply are also HIGHLY susceptible to LED failure. What may seem like a power supply failure may be caused by the failure of one or more LEDs inside the panel (screen).

Is there voltage with the LED plug connected (during brief 'flash')?


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Location: Far, Far Away

 
 
 


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