[SOLVED]i5 13" Mid-2012 A1278 (EMC 2554*) Backlight Flicker after minor liquid exposure.

[TexpertLLC]

[SOLVED]i5 13" Mid-2012 A1278 (EMC 2554*) Backlight Flicker after minor liquid exposure.

MBP "Core i5" 13" Mid-2012 A1278 (EMC 2554*)
Intermittent backlight flicker after very minor liquid exposure.

Customer reported very small amount of bottled water spilled on keyboard, she said she turned it upside down on milk crate for 72 hours. After that it was fine for a couple of days but then the display started flickering.

When I got this in the shop I completely disassembled it, even taking the keyboard out (all 67 screws). There is absolutely no signs of residue, corrosion, rust, or any other exposure to liquid. I even looked closely under the scope. I have now reassembled it and it has the same flickering of backlight (verified with flash light). The flicker is not present when testing with external display, and the intermittent flicker seems to be triggered when connecting the charger (green light present, and changes to orange like normal). The flicker does not occur while in Apple Hardware Test unless the charger is connected. And or course the hardware test found no issues. As always thanks for any guidance.

 

[TexpertLLC]

Hey guys I could really use some guidance on the above described issue. Should i just try to reflow the LED driver chip. I have already tested the LED fuse and it seems to be good. Thanks.

 

[larossmann]

can you upload a short video of this flicker to youtube?

 

[aprendiz]

Corrosion inside the connector creating a bad contact??

 

[dukefawks]

Lid sensor. Disconnect the battery indicator light and see if problem is gone.

 

[TexpertLLC]

I just noticed all of your responses. Thank you so much. I still need help with this, so let me first get the short video uploaded later today, and then I will also follow the other suggestions. Thank again.

 

[TexpertLLC]

Okay the flicker is not as bad at the moment, but it has been to the point where it's as if the backlight is flickering completely on and off. Also the backlight goes completely out when the charger is connected. If you connect/disconnect the charger repeatedly the backlight will come back on but continues to flicker intermittently all the way off, the back on, but mostly staying off unless I start repeatedly start connecting/disconnecting the charger again.

Another note is that the only thing that can make the backlight come back on when it goes off (while the having the charger connected) is to wiggle the charger connector at the DC in jack or disconnect charger completely... then the backlight comes right back on.

 

[TexpertLLC]

Corrosion inside the connector creating a bad contact??

Are you referring to the LCD display connector?

 

[TexpertLLC]

Lid sensor. Disconnect the battery indicator light and see if problem is gone.

Still has flicker even with the Battery Indicator Lights disconnected from the board.

 

[dukefawks]

Replace LP8550

 

[TexpertLLC]

This repair is successfully completed. Thanks again for another very happy customer and helping me further develop the skills our shop has to offer.