820-3476 no green light or ppbus_g3h


Dang. I don't have another retina mbp.
how can I connect an external lcd to thunderbolt? I tried connecting the computer to my tv with a thunderbolt to hdmi adapter i have but that didn't work since the PP15v_tbt and the other TBT rails aren't present anymore. It was present before I replaced that burned u7700 chip.
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I have no idea any more. If you cannot rule out a defective LCD you can mess with the board all you want it is not going to work. This problem could now be the board or the LCD


Okay. Hopefully I can restore the thunderbolt rails so I can at least know that works. I am not getting PP15v_TBT and I traced that back to Q3005. I am not getting anything on TBT_A_HV_EN and that signal comes from U2800 which is covered with a shield.

Do you know what signal turns on the U2800 because maybe that is missing?