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LG 23MP55HQ LED Monitor turns off after a few seconds or flickers

Rick_1234

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Good evening, gentlemen.

I have a problem with my monitor. It turns off after a few seconds or flickers. Shining a flashlight on the screen doesn't show any image, so I guess it's not the "2 seconds to dark" I read in the forum.

To turn it back on, I have to press the power button twice. Then after a few seconds it turns off again or flickers. See video.

Things I tried

- Bought a new AC adapter thinking that was the problem but the problem continues. Checked the voltage of the adapter, 19.5V.
- Tried different HDMI cables and even a VGA cable (with HDMI adapter), same thing. The VGA one works fine on another monitor.
- Tried connecting it to both the graphics card and the motherboard.
- Updated drivers. Today I configured a dual monitor configuration, for that I needed to install the iGPU drivers and the problem persists.

A few months ago it took a few hours for the screen to turn off randomly. Then it started to happen after a few minutes. So I switched to my old monitor.

It's winter right now here (15 C / 59 F), and I have my window open so I don't think heat is a problem. The monitor was right in front of the window for years, and the sun hit the back of it for years, maybe that didn't help.

I've seen that people sometimes attach pics of the mainboard but I don't know how to disassemble the monitor. If it's necessary I'll give it a try, I'm a bit worried about breaking it, that's why I haven't done it.

If you need more info I'll do my best to gather it. I'm open to trying stuff too.

Update:
Right now it stopped flickering and stays on! It's in dual monitor setup, connected to the motherboard. Problem is, for gaming I need it to be connected to the graphics card.
Switched places. Bad monitor connected to graphics card and old one to motherboard. Going pretty good, flickered a bit recently but it stopped.
Flickered a bit more and it turned off. Pressed the power button twice and it doesn't want to keep on. Damn.
 

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You can upload the pictures in your post.

7946767.png
 
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Possibly bad solder joints in the monitor PSU, or bad caps. Because of symptoms resembling late-'00s CCFL-backlit monitors, even though you don't see an image with a flashlight.

Symptoms of bad solder joints:

Randomly and frequently loses power, more likely with cool room temp!

Symptoms of bad caps:

Same as above, even though on computers, expect random crashing as well.
 
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silentbogo

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It's likely a scaler issue. Fortunately for you it's not hard to swap(just need to undo a few screws and unclip the rear cover). It's also not too hard to find, since there are lots of donors with smashed screens all around the world. Specifically it could be a backlight invertor, but it's definitely easier just to swap the whole board.
Possibly bad solder joints in the monitor PSU, or bad caps.
I'm 99% sure it's not caps, since most LG boards of that era and newer have solid caps from the factory.
Shining a flashlight on the screen doesn't show any image, so I guess it's not the "2 seconds to dark" I read in the forum.
It's very easy to miss image with a flashlight on an IPS screen.
 
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