Instructions for the diagnosis and repair of iPhone SE, the failure “It will not charge and will not turn on”
iPhone SE rarely gets into repair.
And so we were lucky! The customer brought his phone with a malfunction “the phone turned off on charging”.
The device did not respond to the connection of the charger and also did not respond to the connection to the PC.
The iPhone SE repair was carried out during the BGA soldering courses.
Diagnosis was carried out in the following sequence:
Приступаем к ремонту.
Подготовка платы телефона для дальнейшей диагностики и замены неисправных микросхем.
Для этого «освободили» плату от корпуса и спаяли защитный экран со стороны NAND Flash.
Visual inspection of the board.
Phone repair technicians know that the most important thing in the diagnosis (troubleshooting) is attentiveness.
Therefore, we devote a lot of time to inspecting and conducting measurements.
It is important to pay attention to the presence of damaged components, oxides and traces of soldering, as well as the effects of the presence of water in the phone.
Carefully inspect the J4600 connector on the bottom charge dock port system ribbon cable.
The connector has no mechanical damage.
We checked the integrity of the connector soldering with a multimeter in the diode test mode.
The connector is soldered and serviceable.
Then, for further diagnostics, we connected the obviously serviceable bottom charge dock port system ribbon cable to the j4600 connector.
Then we applied power to the board by connecting it to the charger and measured the voltage across the C4503 capacitor.
The voltmeter showed a voltage of 4.3 V, but with a working U4500 chip (TRISTAR), the voltage on this capacitor should be 5.0 volts.
It was decided to replace the U4500 chip.
To do this, we cleaned the compound around the perimeter of the charge control chip.
Then we removed the TRISTAR with a soldering iron.
Why did we use a soldering iron, not a hot air soldering station? We are often asked about this during bga soldering training.
The U4500 is removed with a soldering iron in order to exclude heating of the nearby NAND Flash chip.
Using the PS-900 METCAL, we soldered the chip, having previously applied FLUX PLUS gel to it.
Then prepared the contact pad on the Board, washing the remains of the compound under the chip, using a copper braid width of 1 mm.
For intermediate diagnostics and confirmation that we carry out repairs in the right direction; we connected the board (with TRISTAR removed) to the charger through the bottom charging dock port ribbon cable and charger. And we measured the voltage on the capacitor C4503 with a multimeter.
The voltage in the circuit rose to 5 volts.
This indicates that the charge control chip was malfunctioning.
Then we soldered a new tristar marking 1610A3B by the key, after rolling the chip.
After the board temperature dropped, the remaining flux was washed with a Flux-off circuit board cleaner.
Then we repeated the voltage measurement.
To do this, they again connected the board (with TRISTAR installed) to the charger through the bottom charging dock port ribbon cable.
On the same capacitor C4503, a voltage was measured with a multimeter and a value of 5 Volts was obtained.
Then we installed the board in the case and assembled the iPhone SE.
We connected the phone to a USB tester. The ammeter value was 0.93 A.
The phone is charging. Repair completed.
The following equipment and tools were used to repair the iPhone SE:
The article provides a sequence of diagnostics and repair iPhone SE. Following this instruction, you can restore the iPhone charge circuit yourself.