820-4924 no backlight

[jamiehorn1]

Hi there,

I have a 820-4924 with no backlight.

I have 50 volts on PPVOUT_S0_LCDBKLT

i've tested pretty much all of the backlight circuit and it seems fine. U7700 seems to have everything too.

any ideas where to go next?

thanks

 

[jamiehorn1]

there was also a small amount fo liquid near C5801 which i notice has a prob point under for EDP_BKLT_PWM but it's present on pin 8 of the LCD connector at 1.5v

the other liquid damage was only on the SSD but i wonder if this could affect anything with backlight?

 

[JohnB8812]

50 volts on backlight output means it doesn't see a load or the computer is not seeing the light of the screen. Likely a bad screen, screen cable, or LCD connector Have you tried a known good 2015 13" Retina display? 2013/14 will not work!

 

[jamiehorn1]

Hi John, with the original screen i get 0 volts on backlight output so i swapped to a KG screen and i can see the question mark folder with a light. I tried another screen to be sure and same thing... confused!

 

[JohnB8812]

If with the kg screen you get 50 volts, I would say bad LCD connector.

 

[jamiehorn1]

Okay thanks - will get to that shortly

 

[jamiehorn1]

Is there any way to tell for sure that it’s the connector - visually it looks great and I’m sure all of the voltages are present. I guess Pin 1 BCK light output being 50v can justify the connector replacement but just want to double check?

 

[JohnB8812]

https://www.rossmanngroup.com/board...acbook-air-no-backlight-troubleshooting-guide

 

[jamiehorn1]

Awesome thanks!