New to the forum, question about lcd monitor repair

[Memor86]

Hello guys, im trying to fix my old benq desktop monitor
the screen started to go off after waking up the computer, if i turned it off and back on it would work for a couple of second and then go black. (later i realized just the backlight was off). all i had to do was to unplug it from the AC and plug it back again and it would work just fine. well this temporary fix stopped working and now it only works for a couple of seconds and the backlight goes off again.

first thing i thought it was the inverter circuit. i decided to go ahead and take it appart and inspect the circuit board looking for a bad capacitor. sadly every single part looks fine, i bench tested the inverter by just connecting the inverter wires to the lcd panel leaving the signal connector off. the backlight worked and stayed on with no problems, i connected the signal connector and then it stops working.

do you have any idea why this is happening? i thought it was just the inverter but since the light works i think that circuit is just fine and there is something else sending it the signal to go off.

 

[Diver300]

Can you leave the backlight running all the time? You don't mention if the picture is there when the backlight is on, but if it is, you could disconnect the control wire so the invert stays on permanently. The only downside is that the monitor will still take full power when the computer goes off or into standby, but it you turn the monitor off anyhow, that wouldn't matter.

 

[Memor86]

i say that the inverter is ok, because the backlight works just fine if i dont connect the signal connector from the panel board to the screen motherboard. the backlight will remain on until a few minutes when it goes to sleep.

if i connect the signal connector to the lcd panel, the backlight will only be on for 3 seconds.

Yes, if i connect a source (VGA or HDMI) there will be picture displaying properly and will remain when the backlight goes off, i am able to see it if i use an external light source such as a flashlight. if i turn the screen off and back on, it the backlight will turn on again for 3 seconds and go instantly off leaving the picture on the dark.

even without a source connected then if turn on the monitor ON, with the signal wire to the lcd panel, the brand logo will apear which is a pink screen with the brand, and then small box that says no signal will display and then the backlight goes off leaving the picture in the dark.