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Steven, Technician
Category: TV
Satisfied Customers: 1270
Experience:  Lic. and insured, 30 years experience.
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I have a 5 year old 42" LG Led television. It has suddenly

Customer Question

I have a 5 year old 42" LG Led television. It has suddenly over the past week stared losing its picture with the screen going black, sound is still fine and satellite signal is good. We need to switch it off and then back on again, this works for a short time until screen goes black again it seems to be getting more frequent. Can't tell you the model as the tv is mounted on the wall and I cant get to it. Is the tv on it's way out?
Submitted: 4 years ago.
Category: TV
Expert:  TV Tech1 replied 4 years ago.

Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.


It's probably not on it's way out...not at 5 years. But it does sound like it's within the range of needing a tuneup (like a car does) after it's been running for 5 years.


Since you can't get it off the wall, and it takes time to quit working, it's likely a thermal failure where the TV works for hours, then goes bad.

If you turn it off then back on quickly....and it works fine for a short bit...that's usually a microprocessor lock up.


If you have to turn it off and let it cool down for 20 minutes, then it runs fine for an hour, then it fails again....that's usually true thermal failure of a part on the TV set.


But there's a couple things you can try to ISOLATE the problem area.


Can you darken the TV room? Not pitch black, but maybe a stormy day kind of light level?

If so, do this.

When the TV works, and you just turn on the TV, look at the screen the moment you press the power button. BEFORE the picture appears, you should see that pitch black screen gently light up to a subtle gray light level. That's what we call priming the panel before the picture appears.


Priming is important. You don't get a picture until it's primed, and the sound usually follows immediately. So it's important to see what priming looks like, and when it fails....that's the time to --


1] Check and see if the volume bar or menu shows up on the TV screen.

2] Darken the room and see if the screen is gently lit/primed

3] See if you can hear the TV's sound or not.


Then, do you have manpower available to you in the future to remove the TV? You can't service it without a second man or 2 1/2 men (one to disconnect cables and power cords)


Customer: replied 4 years ago.

Hi TV Tech 1,

Thanks for your response! After checking our original question and your response, perhaps we should expand on our first explanation.

The problem occurs more after switching off the set (mainly in the morning) before going out. When we return home and put the tv on, most of the time there is a picture but it seems to "break up" as if there is some interference, coming and going for a few seconds before the screen goes black. It may take two or three attempts (occasionally more!) before the picture settles and works normally. As we have already mentioned this problem is becoming more frequent. It is the same irregardless if we are on digital or analogue (Freeview or Satellite). We have even tried to replay something from Sky Plus in case of some system problems but the screen remains black until we turn off the set and turn it on again (normally after a few seconds but sometimes we leave turning it back on for a little longer). We would also mention that the tv is permanently on "standby" mode when turned off. The tv is an LG 42LF66 Full HD 1080P. We would be able to lift the tv from off the wall.

If the tv does require a "tuneup" and the fault is either thermal or microprocessor lock up, would this be an expensive procedure?

Expert:  TV Tech1 replied 4 years ago.

IF you can see the picture "visually break up" before it goes black, then that would isolate the problem to the TV's main board where the tuner, video input switches, Menu display and microprocessor are all located on. And it sounds like a thermal failure if it takes a bit of time to fail, and turning the TV off....then back on restores the picture to normal, even if it's only for a minute or two before it fails again.


What you don't want to see is BARS from top to bottom appear because that's a TCON board causing that --



On a main board failure, you end up with the picture twisting, flipping, but you don't see vertical lines.


42LF66 main board


EAX36680401 does have a repair kit that's picture related. Fails when cold issue though....


Note the symptoms listed. Anybody you know that can solder?? That's one option I'd consider.


Charles Hyde & Son has some different main boards available --




The way I do this is to get the EAX , EBR number off the main board (it the one with all the input connectors on it) and use that to research the other options available to me.

Plus I look at the option of those caps being replaced since it acts like a thermal failure. Caps do cause issues like you describe, so its something to consider. Soldering? You guys still have those stores you call TANDY over there? Maybe Radio Shack? We have Radio Shack over here. You can buy solder and tools from them. I have one guy on You tube that really goes over the ART of soldering quite well, and the key point -- Wet the tip with solder, and bridge the component with the wet tip. have a base price on the part. You have options on how to fix it. We would need the E-Number off that main board to come up with final plans for repair.