iPhone 10 won’t turn on

From another region, a shipment to Bgacenter received an iPhone 10 with a malfunction – it does not turn on. The device is not subject to warranty repair, since the cause of the malfunction is a fall and mechanical damage. The main task in this repair is to save the customer’s data. And to do this, you need to turn on the device, since automatic data saving to icloud cloud storage was not configured. The phone was repaired during soldering training. iPhone-model A1901, intended for use in the Russian Federation (Rostest). According to the client, the device has not been repaired before.

The phone does not turn on after a fall and as a result is not detected by the computer.

When connected to a USB-tester, there is no consumption.

iPhone 10 after falling

Diagnostics were performed in the following order:

• Using a separator for repairing displays, the phone was warmed up to a temperature of 75 degrees Celsius;
• After unscrewing the Pentalobe screws, we carefully lifted the display module and disconnected the loops;
• The first thing to do is to check the system Board for a short circuit. To do this, the LBP was configured, the current was limited to 500 mA, and the voltage regulator was set to the standard battery voltage-4 Volts;
• Only then did we connect the iPhone x card to the lab;

The ammeter did not show the current consumption of the motherboard, which indicates that there is no short circuit in PP_BATT_VCC (primary power supply) and PP_VDD_MAIN (secondary power supply). This stage of diagnostics, it is possible to produce using a multimeter, without LBP;

IPhone 10 power supply chain

• Then they pressed the power button and tried to turn on the phone. The launch did not occur and the ammeter of the laboratory unit showed a current consumption of 20 mA;
• In order to eliminate the malfunction of the case, loops, cameras, etc.; disconnected all the loops from the connectors on the Board and re-tried to turn on the phone. The device did not turn on, the consumption remains 20 mA. This consumption indicates that the CPU (U1000) does not start or, alternatively, the main power controller (U2700);
• At this stage of diagnostics, we can assume the following options: violation of soldering of CPU pins, ” dump” of the main power controller, violation of soldering of inductors on the power supply of the processor;
• To perform further diagnostics, you need to solder the Board consisting of two halves;
• The STM 10-6 circuit Board heater was used, a manufacturer of THERMOPRO.
  After the x-ray Board was split open, a visual inspection was performed under a microscope. The result is disappointing). On the half of the Board, where the CPU and the main power controller are located, a large number of contacts connecting both parts of the Board are damaged.

Since it is impractical to restore a large number of contacts, a decision was made and agreed with the client to transfer the main chips to the donor Board. Namely the following chips will be re soldered:

• U2600 (NAND memory on the phone),

NAND iPhone X

• U1000 (СPU – central processor),
• U14900 (ANTI-ROLLBACK – ARB).

The sequence of repair of iPhone X

Preparation of the donor Board for the installation of chips, consisted of:

• in order to avoid damage to the donor Board during disassembly of the CPU, the U1000 was cut down on the CNC machine;
• preparation of the contact pad, removal of compound residues and solder residues was performed using flux, copper braid and an induction soldering iron;
• dismantling of the u2600 chip was performed with the mandatory installation of heat sinks;
• dismantling U1490 (ARB). This is a unique chip. And in case of mechanical damage or loss of this chip, repair will be impossible.

Next, the iPhone X Central processor is soldered from the client Board, using the lower Board heater.

The CPU was stripped of the remaining solder and compound. Performed CPU reballing with 0.2 balls.

U1000 iPhone 10

Using a thermal air soldering station, NAND and ARB were dismantled.

NAND iphone 10

Subsequent repair of iPhone 10

On the prepared donor Board, the Central processor was soldered, using a key.

Since the ARB chip is necessary for enabling and further activating the phone, the chip removed from the repaired Board was soldered.

U2600-soldered by key.

At all stages of soldering, heat sinks were used to prevent overheating of the elements on the motherboard.

The next step is intermediate diagnostics. Check for a short circuit.

First turned on the LBP, then limited the current to 0.5 amperes. And connected the Board to the laboratory power supply. No short circuit detected.

Using socket, we connected the two boards to each other and connected the iphone 10 to the laptop.

iSocket

The phone was detected in recovery mode. Then flashed with data saving using the program 3uTools.

iPhone 10 connected to 3uTools

Conclude:

• soldering is performed efficiently,
• the Board is not damaged,
• the CPU is working properly,
• client data is saved.

Then the boards were soldered together using the lower heating for the boards.

Fully assembled client iPhone 10.

For additional verification, we connected a fully assembled phone to a laptop and performed a check via 3uTools.

Checking via 3uTools

Within a few hours, the phone was tested. Be sure to check the operation of sensors, FACE ID, cameras and microphones, etc.

We sent the device to a satisfied customer.

If the iPhone 10 does not turn on, one of the repair options is to transfer the main chips to the donor Board. Repairs are not easy, because one of the conditions stated by the client is that full data storage is required. The time for such repairs is approximately 4 hours, and the cost starts from 12,000 rubles.