Malfunction Phenomenon
iPhone 7 Won’t Turn On With A Large Current, once the motherboard gets connected with the DC power supply.
Trouble Shooting
Large current means somewhere is shorted. Because once the motherboard was connected with the DC power supply, the current jumps to a very high value, we can conclude that the short issue happed before the phone was turned on.
There are several sets of power already stand by there once we connected with the battery or the DC power supply. For iPhone 7, there are 3 sets of powers
- PP_BATT_VCC
- PP_VDD_MAIN
- PP_VDD_BOOST
If any components on these 3 sets of rails get shorted will lead to a large current issue.
For this issue, we checked the PP_BATT_VCC line first by measuring the diode value on pin1 of battery connector J2201, the value was 438, which is normal and means the PP_BATT_VCC line is OK.
Then we continued to check the PP_VDD_MAIN line by measuring the diode value on test point TP0408, the value was 0, this line was shorted.
We also checked the PP_VDD_BOOST line, it was also normal.
Then check the relevant components on the PP_VDD_MAIN rail under the microscope carefully.
Find the capacitor C2610 get black (internal maybe get burned), see the image as below
Remove C2610 and connected with the DC power supply to test again, the short was gone.
Then assemble the phone, the phone can be turned on normally, problem resolved.
iPhone 7 Motherboard Repair Course
