BENQ G2420HD no back light after few sec

[daran]

Hi all,

I have two BENQ G2420HD. One is working normally the other went dark after 1-3sec of normal screen- before not able to see anything with flash light on screen

I changed the the screen to the power board of the working monitor and screen worked fine.

I went and hanged all the capacitors on the power board (dont have means to test capacitors) only have multimeter and soldering iron.

Once the Capacitors were changed the screen comes on for 2-3 sec then goes dark- shining a light on it you can faintly see the display.

I have attached some picture to gi with the issue......please help! I am not fully aware on how to test each component or what each component is in the power board so please point me in the right direction for me to read up on stuff

[dick_barton]

Re: BENQ G2420HD no back light after few sec

What number is printed on IC801, Q801, Q802, Q803 & Q804 on the underside of PSU.
Can you compare the voltage on CN701 between the working and non working set

[budm]

Re: BENQ G2420HD no back light after few sec

https://www.badcaps.net/forum/attach...4&d=1596998731
Is the negative leg of C701 soldered?

[daran]

Re: BENQ G2420HD no back light after few sec

@BudM- C701 is soldered

@dick_barton- I assume you want to know the chips number?

Q801 to 804 is A2790115
IC801- 0Z9933GN,CC780J 30,1139A

unless you mean the other side of the boards with the components on it.- see attached pics - will try and find CN701 and measure voltage -

[daran]

Re: BENQ G2420HD no back light after few sec

@budM- I read this case: https://www.badcaps.net/forum/showthread.php?t=40791

and tested the transformer 1 and 2 points you refer to here on my board-

Transformer 1- shows 2.06 at 20K reading
transformer 2 - i get no reading.

could this cause the 2 seconds to black and for the back lights to go off and not work?

[dick_barton]

Re: BENQ G2420HD no back light after few sec

If the second transformer is not reading approx 2000 ohms as the first transformer then it does looks like the fault.

[Diah]

Re: BENQ G2420HD no back light after few sec

Hi all,

I have two BENQ G2420HD. One is working normally the other went dark after 1-3sec of normal screen- before not able to see anything with flash light on screen

I changed the the screen to the power board of the working monitor and screen worked fine.

when the screen went off... what will happen when you press "wake" (power) bottom, did the screen cone again then off same time? in case the answer "YES" mean you have cut off signal at MB

[daran]

Re: BENQ G2420HD no back light after few sec

Hi guys cant seem to find a new inverter for this board!

Was browsing this forum and came across this post (using LED board):
https://www.badcaps.net/forum/showth...hlight=G2420HD

Could I do the same but use universal CCFL inverter board? like this one:

https://www.ebay.co.uk/itm/Universal...wAAOSwl4lbvlnD

or

https://www.ebay.co.uk/itm/Ultra-MIN...sAAOxy7S5SClL3

Would just need some advice on where to solder the relevant wires to my board.