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LG 47LM4700 - Sound but no picture    
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magilla6002



Joined: 20 Oct 2016
Posts: 2

PostPosted: Thu Oct 20, 2016 7:45 pm    Post subject: LG 47LM4700 - Sound but no picture Reply with quote

Hey, I have a 47" LG. Model 47LM4700. Recently the screen went black and nothing is showing up. The LEDs are all working properly. I got out the trusty meter and checked all the leads on the PSB. On the secondary side of the PSB @ connector P201 everything read normal except for the pin that is labeled as PWR-ON 24V. This pin read at 3.5V. I'm guessing that this is going to be my problem. I just want to verify before I order the new board. I've been an HVAC tech for 8 years so I'm good with low voltage and troubleshooting, but this is my first TV repair. Any help is greatly appreciated!
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JTS1957



Joined: 21 Jan 2009
Posts: 2224
Location: Far, Far Away

PostPosted: Thu Oct 20, 2016 8:02 pm    Post subject: Reply with quote

Those are two pins. P201 is a connector with two rows of pins. The top view of board shows a grid/list of pin functions. The left row lists the pins you can see directly, the right row lists the pins that are hidden by jack's plastic.
Just like Here

PWR-ON should go from 3.5 volts to approx. 0 volts with EACH press of the Power button.

Read this carefully: You have opened the LCD panel and observed directly that each and every LED back light bulb is lighting (and is STAYING lit)?
magilla6002



Joined: 20 Oct 2016
Posts: 2

PostPosted: Thu Oct 20, 2016 8:31 pm    Post subject: Reply with quote

No, I have not fully disassembled and checked the LED boards behind the panel. I turned all of the lights out and can see the lights through the back of the panel with the back panel removed.

I tried shining a flashlight to check for a picture but couldn't see one.

Should I remove the LCD and check the LEDs?

Any tips for removing and handling the LCD to keep from damaging it?

Thanks again!
JTS1957



Joined: 21 Jan 2009
Posts: 2224
Location: Far, Far Away

PostPosted: Thu Oct 20, 2016 8:39 pm    Post subject: Reply with quote

I'd check Tcon board for blown fuse F1 and b-plus first. SJ shows three tcon boards.
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