[SOLVED]820-00045 - MBr 12" 2015 - Built-in screen becomes undetected

[Alan.L]

not liquid damaged.

board had a powering issue, I fixed by replacing the U4700. now the board can boot up.

but...

sometime I get black screen, no image, no backlight, I can hear sound and keyboard's will lit up.
sometime I get picture and everything else are fine.
also sometime when waking up from sleep or put the display to sleep, I get backlight but no picture or no backlight and no picture.
can also cause the system to crash.

Built-in LCD screen doesn't show up in system information.

I've already tried another display and new lcd flex cable.

 

[Alan.L]

https://www.rossmanngroup.com/board...5143-820-00045-no-picture-on-screen-sometimes

 

[dukefawks]

You lifted the bracket on the LCD connector when removing the cable didn't you?

 

[Alan.L]

yes, but not sure about a previous technician as this has been opened before.

you know something tell me

 

[dukefawks]

Never lift it! Probably fucked connector or cable. Or the conductive tape that ground the board to the case at the LCD connector is touching the pins.

 

[Alan.L]

now I'm confused

I thought you meant to lift the flip then you remove the cable, see my pic:

 

[dukefawks]

I never lift it as it tends to fuck up. It is fine just sticking it in. Is the conductive tape under the cable not touching anything? I bet it is folded under the board or touching the connector pins.

 

[Alan.L]

you might be right about the conductive tape, they are everywhere.

I've post result after I find a way to isolate..

 

[dukefawks]

It connects the board to the case, not on the cable. If the board was out you have had to peel that tape away.

 

[Alan.L]

thanks Duke, you was right. After I isolated the leg pins of the connector with kapton tape, haven't had any problem for 2 days. crossed fingers!

 

[Paul Daniels]

Oh GREAT, I just had one of these the other week, waiting on a replacement keyboard, and yes, I've flipped up the top-latch on the metal FPC connector too; for future reference, how are you supposed to extract the flex from the board connector... or don't at all?

 

[Alan.L]

hold the connector with the flip closed with your finger then gently pull the flex out with your other hand's fingers.

 

[Paul Daniels]

So basically treat it like an old friction fit FPC socket?

 

[dukefawks]

and if you take the board out make sure the conductive tape is in place and not touching the pins.