Malfunction Phenomenon
iPhone 7 Rear Camera Not Working.
The rear camera could not be turned on when taking pictures, but the facing camera works normally.
Trouble Shooting
Replace another camera to test first, but the problem still unresolved. So we took out the motherboard and checked the rear camera connector J4501 by measuring the diode value of all pins on the connector.
The diode value on pin 18 is 0, which is abnormal, which means the relevant circuits of pin 18 get shorted.
From the schematic, we found this line is the power line of 2.9V to the rear camera, which is outputted from pin A2 of U2502. U2502 is an LDO (Low Dropout regulator), it helps to make the voltage from a high value to a low value. Besides the LDO, there are also many capacitors on the line. If any one of these caps gets shorted can make the whole line shorted.
Use the rosin inspection method to find out C2531 is shorted, remove C2531 and test again, the diode value back to 543, the short had gone.
We continue to assemble the screen and tested it, the rear camera worked normally, problem resolved.
iPhone 7 Motherboard Repair Course
