After we reboot this iPhone got from my friends, all of the functions showed normal, switched normally between front and camera. But the iPhone front camera is shown full black screen when taking photos. As shown in picture 9-10-1
First, we need to judge where the problem comes from. This failure is generally caused by data hub, because the problem came up after falling, so it is likely to be caused by the disconnection or iPhone CPU false welding.
Disassemble and install a new camera, same fault phenomenon remains the same, the problem is determined on the iPhone6 Plus motherboard.
Power off the phone and measure the ground value of the camera interface, there is no any problems has been found, also the voltage needed for the camera is measured normally. This is a rare situation. If the CPU is false welding, the resistance shouldn't be normal, so there is almost impossible for getting a bad CPU.
Test the interface resistance again, infinity is detected when the 19th pin AP_BI_FCAM_SDA_FONN is measured. As shown in picture 9-10-2.
Many tests found that sometimes it's infinite, sometimes more than 500 of the resistance, but according to the data cable comparison found that under normal circumstances, it should not exceed 500. Measured value on multimeter is as shown in picture 9-10-3.
Tracing the source, it was found that the AP_NO_FCA_SDA_CONN was connected to the CPU by inductance, and the resistance of the 1 pin measured by FL1114 was normal. As shown in picture 9-10-4.
After measuring FL1114's 2 pin infinity, we find that some inductance is loose, after sodering, 19 pin resistance become normal.
Booting and entering into the system to test, the front camera has been fixed already!
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