Question about LG 55LH40 55 in. LCD HDTV
While watching TV the screen goes black no sound either. Look at backside of tv thru the vent slots you see light on. There is also a noise coming from the lower right side (looking from the back of the TV) we shut off the TV wait awhile turn back on we get picture again for 15-20 minutes the goes black again.
Start simple by using different cables, whether they be HDMI, VGA or standard COAX cables. They could be losing the connection. Also, it's possible the power supply is wearing out and it gets too hot. You might want to simply try some spray air duster type thing to clear out any dust that can make it hot.
Posted on Sep 21, 2014
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Posted on Jan 02, 2017
I would bet on some component(s) have become thermo sensitive. Most of the time capacitors can do this type of thing. Most likely the defective caps could be in the power supply.
To locate the defective caps, you would have to be able to run the supply and use the combination of a heat gun and freeze spray (liquid air spray) for cooling. At the same time you would have to monitor the output of the supply to see the components that cause the output change.
It is also possible to have thermo sensitive components on any of the other boards. This would also require proper troubleshooting.
The service rep would replace boards until he found the defective board. Then he would return the set with the new board and the bill for his work.
If your set is out of warranty, it may be better to consider a new set. Servicing these can be fairly involved and expensive.
Posted on Jun 26, 2012
For bobby11 and luis, it is the power supply. Part Number EAY34797001 in the 42" and EAY34796801 in the 32". This is a known problem, and somebody should start a Class Action against LG over this one. Part is available online and easy to swap out for anyone with the most basic knowledge.
Posted on Oct 08, 2008
SOURCE: LG 47" LCD FLAT SCREEN
> IF IT WASNT DIGITAL HD I WOULD HAVE SUSPECTED HIGH VOLTAGE POWER SUPPLY BUT THAT DOES NOT EXIST HERE.
Well, not completely true; the fluorescent backlight is still a high voltage device, even if only hundreds of volts instead of kilovolts, and either the lamp(s) or the power supply for it (them) is causing the dropout of your picture. When it does it next time, look at the screen from various angles, I think you will see that video content is still there.
Posted on Sep 14, 2008
This could be 1 of a few things here. Without opening up your set and trying to look at voltages or indiciator lights I couldn't tell you exactly without some more info.
Without looking at it myself here are my thoughts and where I would first look at.
It may be a main board because:
1) Main board processes all your audio/video signals. Bad main board means bad video processing. Could do that. Especially if the main board is not sending the right signal or a bad signal to the rest of the boards so they don't do their jobs.
It may be a power supply because:
1) Power supply is well, the power supply. If it's sending inadaquete voltage to the main board you may not be recieving enough juice to keep that main board doing your video processing or further up the line keeping enough juice flowing to your TCon board to keep it telling things where to go and what to do. The power supply sends voltages to your Ballast board(controls your lights) and to your main board through which power is supplied to your TCon board via a LVDS line and a +12/+16V signals. If the power supply isn't pumping out enough juice to keep the TCon or Main Board running, it could be a problem. By the same token it could be that your P/S isn't sending power out to your ballast board.
It could be a TCon because:
1) If the TCon is bad, you won't get your pictures. This could be the TCon board itself or the LVDS cable from your TCon to your Main. However, with few exceptions, if it's a bad TCon you're looking at a total panel replacement.
It could be a ballast board because:
1) The Ballast Board controls the lighting behind the LCD screen. If this isn't working right you won't be seeing much of anything without that back lighting. If this is bad, it's a panel replacement. These are not field replaceable items by LG.
Based on the symptoms, without more data or a eyes-on view of it, I would say you're most likely looking at a Main Brd or PSU problem.
Posted on Feb 21, 2009
SOURCE: no picture but has sound
hey i think i know your solution on how to fix that you should get another tv lol jp go to my web site and I'll tell you a couple of methods to try.its meatspin.com
Posted on Feb 28, 2009
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