Chosen Solution
Hi, I’ve got a customer’s iPhone 5 that is completely dead. I got 0A on power supply (connected on battery connector) whit power button pressed and released. I tried hard reset, DFU mode, replace the battery, replace the screen and power on only the board. However the phone doesn’t respond to anything. I take off the shields and checked the board, but it looks ok, no corrosion points, no components smoked. I would like help to start the board analysis. what is the better points to check in this situation? What is the lines and the values that I need to check? Thanks Felipe UPDATE: I just put the phone to charge and after some minutes the all phone warmed up.
When dealing with a “dead” phone, you have to start at the beginning and check PP_BATT_VCC, PP_VCC_MAIN and PP5V0_USB. I would start by checking to see if those rails are shorted to ground. If one of these rails is shorted to ground, then you will need to identify what is causing the short. It could be a bad decoupling capacitor, conductive debris or defective IC that is directly supplied by those rails. If they are not shorted, then you can connect, preferably, a known-good battery (or a current limited DC power supply with the appropriate connector adapter) to see what voltage you measure. If the voltage is low or lower than the battery voltage (which you measured before plugging it in ;>), then there could be a short circuit on secondary subsystem that is causing the battery or DCPS to be current-limited. Then you move onto the PMIC and check the voltage rails it generates: The PMIC generates a lot of voltage rails. They are all important (for obvious reasons) but the ones to check first are as follows: PP_CPU, PP_GPU, PP1V8_SDRAM, PP1V2_SDRAM, PP_VAR_SOC, PP0V95_FIXED_SOC, PP3V0_Tristar, PP3V0_NAND, PP1V8_ALWAYS and PP1V0.The PMIC also generates, what I would consider secondary, yet still important voltage rails for the following sub-systems: PP3V0_MESA, PP1V8_VA_L19_L67, PP3V0_PROX_ALS, PP3V0_PROX_IRLED, PP3V0_IMU, PP3V3_USB Note: The net names change slightly from one iPhone model to another Start probing and report back.
