Chosen Solution
Hi, I got some “dead” motherboards to repair and I have problem with this one. It is A1778 model. It was missing some chips (BB PWR, Tristar and Audio IC), so I replaced them. Without audio IC it was working fine, got signal and everything, but when I put audio IC back the phone starts bootlooping. I have done jumper wires, tried another chip, but it is always the same. Any ideas where might be a problem?
Have you ruled out parts? Installing the audio IC can bring into play the front camera flex assembly, faulty battery and dock connector. If you are sure it is not a parts issue you can continue diagnosing the board. · Have you tried a different batch of audio IC’s? · Are you re-balling them? · You need to diode the pads under the IC and compare with a working board. · Have you checked all the resistors under the edge of the shield? They can occasionally get nudged. · The most important one is have you jumped D12 to G12 and tested?
