820-3787: No image on display

Have this board, no liquid damage or corrosion. Came in for no image on display, but when i first power it on, it worked just fine until I changed the energy saving setting to always use the AMD GPU and not the Intel. As soon as I made the change, and it switch to black screen.
i was going to replace U9600 but decided to replace U9300 first which didn't fix it.

My question, can i use a U9600 chip from a 820-3332 or 820-00426 board or as an alternative, i can purchase this chip from DigiKey.com?
On the schematic, apple part numbers 341S3565 and 337S4313 match on both the 3332 and 3787. Plus the spec info from BOM page matches DigiKey.com.
 

2informaticos

Administrator
Staff member
U9600 has firmware, but I don't know untill which point is board dependant.
New chip probably will not serve...
 

2informaticos

Administrator
Staff member
50V on backlight output means open LED strips.
Bad LCD connecotr, video cable, or display.
If you get that voltage, image should be there too.
Did you check external video?
 
No video on external display or on another known good display.
Also fan ramps up to max. Ive tested with another frame to confirm issue isn't with keyboard or trackpad.
 
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