VPCCA290X (MBX-239) No backlight in LED screen

[orientalsniper]

Re: VPCCA290X (MBX-239) No backlight in LED screen

mmmmm, I shined the screen with a flashlight behind the screen, I don't see anything, but I can see BIOS screen perfectly with VGA connection to external monitor. And I've tested about 10 screens already.

[trebo]

Re: VPCCA290X (MBX-239) No backlight in LED screen

mmmmm, I shined the screen with a flashlight behind the screen, I don't see anything, but I can see BIOS screen perfectly with VGA connection to external monitor. And I've tested about 10 screens already.

try shinning a bright torch into screen from front in a darkened room

[orientalsniper]

Re: VPCCA290X (MBX-239) No backlight in LED screen

Just tried that in a completely dark room, I think I'd have to order the LVDS.

[dspok]

Re: VPCCA290X (MBX-239) No backlight in LED screen

@orientalsniper
if 19v is there then LED should lit up.
it now looks like LED on the screen is dead, & i'm cofused that you said you have tested about 10 screens but problem is still there.

[dj_ricoh]

Re: VPCCA290X (MBX-239) No backlight in LED screen

you never seen a cable or a mobo that destroys screen?
pff join my club you will see weird crap all day

[scsblackdragon]

Re: VPCCA290X (MBX-239) No backlight in LED screen

did we establish that all the fuses are either short or open circuit?

[orientalsniper]

Re: VPCCA290X (MBX-239) No backlight in LED screen

Yes, I'm sure it's not the screen, I took it to another friend's repair shop, combined we must had tested 15 different screens. I'm still waiting for the LVDS, I will report back with results.

[orientalsniper]

Re: VPCCA290X (MBX-239) No backlight in LED screen

I just tested with new cable, still nothing in screen, I'm not even sure if it's the backlight anymore since the screen receives the 19V.

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

if u change 100 leds, it will not work

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

if u change 100 ribbons, it will not work

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

it is problem in the motherboards i/o chip. change it , it will be ok.

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

the led light switching voltage comes from the io chip. though u have found the 19 voltage u are not getting the sw voltage and thats why the light is not getting on. check for 3v/5v at least in 2/3 pins beside 19 volt.

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

alternative way:

as per my pic,

u see pin #2 have no volt. if it so, then cut the pin #2 ribbon and short it with pin #3. hopefully it will work.

[orientalsniper]

Re: VPCCA290X (MBX-239) No backlight in LED screen

masud, thank you, you were right! The 3V and 5V were missing, but unfortunately I couldn't work with the laptop any longer. For any other who might have my problem, check the pins 35, 36, 38, 39 and 40 (3.3V or 5V, 19V). What you do is supply it from somewhere else in the cable or motherboard.

Check the pinouts from this datasheet: https://cdn.badcaps-static.com/pdfs/...e92d5f01f6.pdf

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

just ensure both 35 and 36 pins are getting 3v/5v.

[masud]

Re: VPCCA290X (MBX-239) No backlight in LED screen

ofcourse there should have 19 volt in 39 and 40 pins.

[ravi_1617]

Re: VPCCA290X (MBX-239) No backlight in LED screen

I have same board same problem.
external display ok. internal led display i can see just flash like and no image no light .
19 volt present on screen side. no trace of signals on any pin on cro.

[kazia]

Re: VPCCA290X (MBX-239) No backlight in LED screen

thanks...

[Laptop1703]

Re: VPCCA290X (MBX-239) No backlight in LED screen

input volt 19 missing what problem