ASUS VW220T power supply

[nbdy]

the problem is that the monitor turns on,and then off ...

the board AIP-0180 looks OK

picture

https://www.dropbox.com/s/2w59cfipn0...83511.jpg?dl=0

[budm]

Re: ASUS VW220T power supply

Do you mean that the power LED goes off or it goes into standby? Or are you talking about the backlights come on and then go off?
What DCV do you get at the white connector and the black connector on the right side of the board of your picture? There are labels for the pins but the picture is not clear enough to tell us what the pins are for.

[nbdy]

Re: ASUS VW220T power supply

Goes to stanby,the black connector is :

O/F - BL
5.2V-5.2V
GND - GND

will measure tommorow,and the white connector is not used on this monitor

GND
GND
+5V
+5V

[nbdy]

Re: ASUS VW220T power supply

Meassured the 5V it is always present (the board is alone without the diplay board)

[budm]

Re: ASUS VW220T power supply

If 5V is always present then your power supply is OK because it is an always on power supply.
You need to have all the boards connected, so what DCV do you have on the OF and BL pins?

[nbdy]

Re: ASUS VW220T power supply

O/f - 0v
bl - -5v

With the display board

O/F - 0V
BL - 225mV

the 5V is constant

btw. this is the second time this happens,the first time I changed the power board,but it is a little expensive now for me

Could I check the backlight with something

OK the third check with all connected, the screen goes on then off,on and off and into standby
the lamps go on/of,on/off and into standby

[budm]

Re: ASUS VW220T power supply

BL with -5V is not correct, it should never be Negative Voltage.

"OK the third check with all connected, the screen goes on then off,on and off and into standby
the lamps go on/of,on/off and into standby"
When it is cycling like this, is the 5V is still very stable?
The main board sends the two command signals to turn on the backlights and Dimming control signal.
The main key is to know for sure if the 5V is steady or not.
I also need good clear pictures of the bottom side of the power supply/inverter board.

[nbdy]

Re: ASUS VW220T power supply

OK,now with all on ...

The O/F goes from 0-2.2-0V (2.2V is for 2-3 sec)
BL is 220mV

The 5V is constant ...

There is a little noise like a flying bug

https://www.dropbox.com/s/3cfldcsy7f...73654.jpg?dl=0

https://www.dropbox.com/s/c280326k7m...73701.jpg?dl=0

BTW.:changed the 0.33uF at the 220V line,all the same ...

[budm]

Re: ASUS VW220T power supply

That CX101 cap is safety cap for line filtering, the power supply board will work without it.
You can try force on the power supply/inverter board to verify if it is OK or not by disconnecting the main board from the power supply board first and then install 470~1K (1/4 will do) resistors, one between A and C, and another one between B and C, then power up the board and you should see the backlights come on and stay on as long as the AC power is being applied to the board.

[nbdy]

Re: ASUS VW220T power supply

Added a 1k resistor,the monitor goes to sleep (alone mode)
With a computer connected the monitor goes on,but without a picture

and yes the backlights stay on (tryed on a different screen)

[budm]

Re: ASUS VW220T power supply

Added a 1k resistor,the monitor goes to sleep (alone mode)
With a computer connected the monitor goes on,but without a picture

and yes the backlights stay on (tryed on a different screen)

With the added resistors for testing the power supply/inverter board, you must not have the main/logic board connected to the power supply/inverter board. if the backlights come on and stay on (you will not have pictures on the screen of course) then you know that your power supply/inverter board is OK.
Next, you will remove the resistors and then plug the main/logic board back in place, then disconnect the cable between the LCD panel and the main/logic board and see if you can turn on the monitor and the backlights will come on and stay on (and of course you will not see any pictures on the screen), notes: the monitor may go into standby mode so you should hook it up to running PC.
So far i would say that the power supply/inverter board is OK.

[nbdy]

Re: ASUS VW220T power supply

The backlights stay on with computer attached to main board ...

Without computer it goes to sleep

[nbdy]

Re: ASUS VW220T power supply

Tested now with another screen,and all works OK ...

With the old screen it goes to standby ...

[budm]

Re: ASUS VW220T power supply

So you have more than one of this monitor that you can swap the boards around? Sounds like you have bad screen.

[nbdy]

Re: ASUS VW220T power supply

Thx for all help,yep it is the screen ...

The other screen was left by some frend "you will need it sometime" ...

Now i know the screen is working ;-)

Could I try to change the lamps,or is it somthing else ???