Got the repaired iPhone 7 Plus, we found it was repaired before. So we doubt there may exist something abnormal inside of the phone body, cuz the former problem is about the phone audio IC, which ask a simple solder operation.
Anyway, we need to disassemble it and check the current, compared it with the normal value, we advise the wuxinji dongle.
According to previous repair experience, we know there are 2 camera power supply transfer tube on the WIFI IC are easy to virtual weld, after remove it, and reinstall it, the failure still there.
Picture 20-10-1
Use digital multimeter to measure the grounding resistance value for iPhone rear camera J3001 and J4501, the data is normal. And the power supply for camera socket tested also is normal.
Picture 20-10-2
Measuring the I2C bus on J3001 and J450，when measured the J3001 2 pin, finding that it only has 0.4V voltage, but in the normal case, the normal voltage of I2C bus should be around 1.8V. Open the WUXINJI Dongle to check iPhone schematic diagram, this I2C bus via safety resistor R3301 to M2600, pull-up supplied by R4604 resistor.
Picture 20-10-3
Combine iPhone bitmap to find R4604 resistor.
Picture 20-10-4
One side of the resistance value measured of R4604 is normal, the other side is 0.4V, which is obviously wrong，we suspect the pull up resistor is damaged. With the help of the QUICK 861DW hot air rework station and tweezers, we replace the pull up resistor, and the measure it again, now the both sides voltage of resistor are back to normal.
Picture 20-10-5
Enter the systems and test it, the failure has been repaired!
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