Monitor flashes after some time on (ASUS VW220D)

[magoscuro]

Hello,

I've a problem with a 3 years old Asus VW220D monitor, after a while turned on ( 30 min to 1 hour ), the screen starts to get random flashes.

Here a video of the problem :

Asus VW220D Flickering problem - YouTube

I've tried the following.

1. Change VGA cable
2. try with a different monitor on the same computer (no problem noticed)
3. put the monitor on different computer ( problem ocurr after a while)
4. Dissasembly the monitor and reassembly.

When I activate the menu I notice the same flash over the menu, so I think it's not a signal problem.

I think there's a component that stops functionning OK after some heat, but I don't know how to locate it.

I would like to repair it, but I've got no more clues.

Can you help me?

Many thanks

thanks
Christian

 

[William Gaatjes]

I looked at the video.
That is not your backlight but the processing of your video signal.
But can really be anything besides that.
It is an analog input only. That means the analog signal is converted into a digital signal , processed and then the lcd panel is driven.

How did this start ?
Did you drop the monitor ?
Was there an electrical disturbance at the 110V /230V outlet ?
This makes me think of a lightning strike but i am really just guessing.

Can be loss of sync signals because of loose connector pins.
Bad solder joints.
Check for bulged electrolytic capacitors. This is very common these days.
Cracked smt ceramic capacitors can happen.

http://www.ami.ac.uk/courses/topics/0179_fmcc/index.html

 

[William Gaatjes]

If it happens after being on for a while, it means that temperature might play a role here.
Buy some freeze spray and gently spray the cold only on the low voltage part of the board.
Caution :
Not on the 110V 230V AC section and not on the CCFL inverter !
Because there is an amount of condensation that will happen when using freeze spray. And you may by accident create a conductive path between a high voltage part and a low voltage part and blow up the monitor.


If you want to take the safe but time consuming method :
Turn the monitor off and let it cool off to make the flashing disappear.
Use a heatgun or a hairdryer with a small nozzle to locally heat parts of the pcb to track down where on the pcb the problematic component may be located.
When it starts, turn the monitor off, let it cool down until the flashing disappears and repeat the method to narrow down your search.
Repeat again and start looking with a magnifying glass if you can see something.

 

[magoscuro]

Thanks a lot for your answer, you're right, I'm go to test the temperature hypothesis, before I'm going to cool the entire card with a fan, and see if the flash disapear. After this I will apply the safe method .

Thanks you a lot for take time to answer, I'm go to spend some time this Week End...
and come back with the news!!