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Old 12-27-2014, 08:49 AM   #1
johnjgjohn
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Default Lg lcd flickering screen after 15 mins help

Hello all merry xmas
Ive got an lg lcd when i power up everything works as normal for the first 15-20 mi s then the screen starts to flicker or pixelate ive checked for bulged caps and checked ribbon cables but not sure were to go from here ive got a video can it be uploaded here? Then u can see what its doing it gets worse the longer its on
Thanks for any help
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Old 12-27-2014, 11:01 AM   #2
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Default Re: Lg lcd flickering screen after 15 mins help

can you post good clear pics. of each of the boards, and one of how they are all connected, what is the model number?, use caution when working with power supply HIGH VOLTAGE on primary side.
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Old 12-27-2014, 11:50 AM   #3
Ltank
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Default Re: Lg lcd flickering screen after 15 mins help

Check P.S. voltages on P.S. accoring to silkscreen legend near connectors. 24vdc to inverters should be stable. check backlight on command , PS-on, standby voltage then tell us what you have. Also check the larger capacitors on the inverter boards that power the backlight bulbs. Use a DVM with negative (black0 lead) on chasis gnd
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Old 12-27-2014, 01:31 PM   #4
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Default Re: Lg lcd flickering screen after 15 mins help

The model no is 37lc55-za
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Old 12-27-2014, 01:34 PM   #5
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Default Re: Lg lcd flickering screen after 15 mins help

Here is some pics
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Old 12-27-2014, 01:36 PM   #6
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Default Re: Lg lcd flickering screen after 15 mins help

Close up of psu
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Old 12-27-2014, 01:42 PM   #7
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Default Re: Lg lcd flickering screen after 15 mins help

take the power supply off the TV and check for cold solder joints on the transformer the main inverter transformer the one on the top right
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Old 12-27-2014, 03:33 PM   #8
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Default Re: Lg lcd flickering screen after 15 mins help

Surely if it was the inverter then i would loose backlight? I tried upload a vid but was taking like 20 mins from my fne then i cancelled it the backlight doesnt flicker or go out its just pixelated like when u have a bad signal on freeview the picture gets lines through it
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Old 12-27-2014, 03:35 PM   #9
freakaftr8
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Default Re: Lg lcd flickering screen after 15 mins help

sorry missed that part yes it does sound like a main board problem. is it doing this on all inputs or just one?
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Old 12-27-2014, 03:55 PM   #10
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Default Re: Lg lcd flickering screen after 15 mins help

Quote:
Originally Posted by Ltank View Post
Check P.S. voltages on P.S. accoring to silkscreen legend near connectors. 24vdc to inverters should be stable. check backlight on command , PS-on, standby voltage then tell us what you have. Also check the larger capacitors on the inverter boards that power the backlight bulbs. Use a DVM with negative (black0 lead) on chasis gnd

Ive checked all voltages they all seem to be what is stated and are all stable
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Old 12-27-2014, 04:00 PM   #11
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Default Re: Lg lcd flickering screen after 15 mins help

Doing it on all inputs when i first turn it on it works fine for about 20 mins then starts flickering a little but gets worse as time goes so must be heat related
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Old 12-27-2014, 05:27 PM   #12
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Default Re: Lg lcd flickering screen after 15 mins help

Here is a video of what its doing http://youtu.be/hkgiG7O7Jm0
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Old 12-28-2014, 07:36 AM   #13
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Default Re: Lg lcd flickering screen after 15 mins help

Does anyone know what would cause this have a look at the video above thanks
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