ASUS VH222H 21" : no power when LCD plugged

[_max_]

Dear friends,

my ASUS VH222H 21 inch monitor suddenly is no longer running, the power button does not have effect and the blu pwr led remains off.

I completely disassembled the monitor to do a visual inspection.
Unfortunately, even using a magnifying glass, I have not been able to identify any damaged capacitor, no component visibly burned or damaged runways.

I did a test just by connecting the high voltage to the LCD panel, leaving disconnect the LVDS cable, and surprisingly the monitor turns on and the display lights up. Of course, no image appears.

If I connect the LVDS cable, the monitor remains black and not even turn on.

Monday morning I would like to take some high resolution photos of the main board and power board to post here, if I had missed some details you might definitely help me.

In the meantime, I would argue with you experts on what could be the cause of such a failure.

For example, since the display lights up, is it fair to exclude a priori a problem on the inverter / high voltage circuit?

thanks
max

[selldoor]

Re: ASUS VH222H 21" : no power when LCD plugged

I did a test just by connecting the high voltage to the LCD panel, leaving disconnect the LVDS cable, and surprisingly the monitor turns on and the display lights up.

max

How did you apply the high voltage - what voltage? Was this from an external source.

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

How did you apply the high voltage - what voltage? Was this from an external source.

I just connected all the connectors for LCD lamps , mainboard, power board but leaving the LVDS cable unplugged.
No external surces connected.

[selldoor]

Re: ASUS VH222H 21" : no power when LCD plugged

Ok Have you ohme tested the lvds cable for shorts. check for bent pins on connectors.
Pictures on Monday might help - one of the tcon or panel board as well.

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

Here there are my last pictures of the boards: Main Board and Power Board.

It looks like there are no bad caps or other broken components.

What is strange is that only when the LVDS cable is plugged, the monitor does not switch on.

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

Here are a few pages with schematic diagrams of a similar power board

@selldoor

I really do not see how I can lead to short circuit in the LVDS cable or bent pins ... it is really crowded... How may have been broken by itself?
It presented this defect suddenly and had never been opened before.

[selldoor]

Re: ASUS VH222H 21" : no power when LCD plugged

@selldoor

How may have been broken by itself?
It presented this defect suddenly and had never been opened before.

Well that's ok then . You can apply that thinking to to the entire set and every component on it. If your not going to test the part that is causing the problem
I will just move on to someone elses thread - bye.

Perhaps someone else will suggest something that is easier for you test.

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

Thank you selldoor, any suggestion is welcome!
Only it is a bit difficult to find pins to check with the multimeter.

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

No idea here?
I am stuck, I have not to much experience repairing display

[_max_]

Re: ASUS VH222H 21" : no power when LCD plugged

I am stuck