LG 47LB650V no picture - not backlight

[olegeisler]

Hi

I got this one for free LG 47LB650V chassis LD42B, and would like to fix it, and give it to a friend who is living on a very tight budget.

The previous owner just told that it went dark, and I thought it was the usual backlight issue - but no.

I feed the backlight from an external DC source, and it seems to work fine - doing this, and starting the TV from the remote gives vertical bars, see picture. It seems like no update of the LCD takes place, since the "bars" just fades slowly when I shut off the TV from remote.

So this is what I know:
Reacts on remote on/off
No - menus, nothing
Vertical bars like in picture
No blinking lights, except for during boot up
All voltages from power supply correct, except for the backlight drive - but this is due to the mainboard not activating the DRV_On signal

Service manual and chassis pictures attached

Just a mainboard ? ( this means it will go to the eternal electronics heaven ) - Or any better suggestions ?

I have all kind of equipment and knowledge to do any experiments / measurements, but I am not that experienced in LCD TVs - any help highly appreciated.

[attainteddragon]

Re: LG 47LB650V no picture - not backlight

on the top edge of your first pic, there are a couple of dark patches with distinct edges. remove the bezel and check the screen at that point. you might be looking at a broken panel.