820-00138 No image to display. Works fine on External

[Dukky Repair and Recovery]

Hello all. First post here. so bare with me.

Symtoms: No image to internal Display. Works fine on external.

Still trying to understand the Retina eDP Display Circuit. I can't find a BRD file for this Model so I'm a little confused as the PP5VR3V3_SW LCD line differs to other models.

Tested with KG Display - No Change

No Signs of Liquid Damage.

L3800 has a spike of 5V then goes to 0V. I'm guessing thats normal and is meant to power the display so it can talk over DDC?

PP5V_S4 - 5V

I can not find U8300 on the board so i am unsure if i have LCD_PWR_5V_RC.

Seeing as i have no image and no backlight I'm guessing its a DDC issue. What line handles that on the Retina models? LCD_HPD?

Any help is much appreciated.

 

[dukefawks]

EDID information is read through the AUX DP lines. In this case the first suspects would be the LCD cable or the LCD itself, try a known good assembly. Must be 2015 model, older LCDs don't work.

 

[Dukky Repair and Recovery]

Just double checked with the Tech that sent this to me. He was using a mid 2014 display... ? now that ain’t gonna work is it? Thanks for making me double check that. Will test with a mid 2015 when I’m in.