820-4924 - Water Damage - No Video

[pws6074]

I get this board and i wondering if you guys can help me out.
The board is 80% fine, however the liquid hit the J8300 and close to that.
The PIN 1 on J8300 looks like have short, so i replaced also the cable.

Around U7700 is pretty clean, don't have corrosion.
* I get external video

Measurements:

Q7700
- Pin 1 2 5 6 = 0v
- Pin 3 4 = 12v

L8300
- Pin 1 = 0
- Pin 2 = 5V for 10 Seconds after 0v

U7700

Pin 1 2 3 4 5 = 0.4V
Pin 6 = 5v
Pin 7 = 0v
Pin 8 = 5v
Pin 9 = 12v
Pin 10 = 12v
Pin 11 = 12v
Pin 12 = 0v
Pin 13 = 0.2v
Pin 14 = 0.2v
Pin 15 = 5v
pin 16 = 5v
Pin 17 = 0
Pin = 5V
Pin 19 20 21 22 23 24 = 0V

SMC LID = 3.4V
EDP_PANEL_PWR - 3.4 after 10 sec goes to 0v
PPVIN_S0SW_LCDBKLT - 0V
PPVOUT_SO_LCDBKLT = 0V

Diodo Mode Pin 1 on J8300 - 1.1v

 

[dukefawks]

LCD not recognized. L8300 pin 1 having 0V and pin 2 at 5V is not possible. Flow is from pin 1 to 2. If connector is not damaged then first thing is to connect a known good 2015 LCD assembly.

 

[pws6074]

Yes. You are right, Duke about Pin 1 and 2.
I Just tested with another screen 2013 and i get mark folder with light in the back.
I will try check the same screen and see what happen.

Thank you

 

[iambehr]

I have had water get in under the clutch cover and wreck the LCD / backlight board. I have replaced a fuse and a connector on that sub board when I was in a bind for parts.
You can easily replace that LCD cable as well.

 

[pws6074]

I did, but still don't get backlight.
I guess the problem is on the U7700

 

[dukefawks]

What is voltage on pin 1 of LCD connector? Working LCD must be connected and image must be present.

 

[pws6074]

0.2 V Pin 1 and i get question mark with light in the back.

 

[dukefawks]

Did you try a known good LCD assembly? LCD needs to "talk" to U7700 to enable it.