Professional Cell Phone Repair Guide

We received an iPhone 6 V version device, according from the owner: It got water in, we find there is electrical leakage when connecting it to electricity, which triggers large current. Here we will introduce the details of the fault maintenance, hope it will help you! Motherboard waterproof stickers changes into red, indicating that the motherboard got into the water, the power supply  shows leakage 31mA when electricity is connected. As shown in picture 4-4-1. Short start signal boot, current jumps into 223mA as shown in picture 4-4-2. This kind of fault is usually caused by chip damage after water inlet, measuring each power supply is normal value, measuring the data cable  of the 12C0 to the ground value is only 002, as shown in picture 4-4-3, indicating that the 12C0 is short-circuit to the ground, the normal value should be about 400. Combining the above phenomenon, the fault target is locked in the U1602 flash power supply IC, U1503 fingerprint power supply...

The cell phone we will repair is an iPhone 6 with screen touch fault. What is the problem came from? Customer mentioned the  screw  on motherboard is snapped, after repaired, the touch function is not working. How to get the best solution for it? First, power on iPhone 6 and test it, the touch screen has no response and there is no white stripes. In this situation, the generally black touch IC  does not work or CPU can't recognize the touch IC. According the trouble phenomenon there could be disconnect. After disassemble the iPhone 6, we can find that the iPhone has been repaired, and it's more serious. As shown in picture 4-1-1 and 4-1-2. First use digital oscilloscope  to measure touch IC, it shows 5.1V, 5.7V, and also has the voltage of black touch ic. This result indicates that both the white and black touch IC all is working, probably it's a sync signal problem, check it with schematic diagram. As shown in picture 4-1-3, 4-1-4, 4-1-5 and 4-1-6. ...

iPhone 6 touch is properly ineffective, when touch is not working, screen  can display normally; the touch gets complete failure when there are some not obvious lines on screen. The device got water damage and screen was replaced, It's still not repaired well though repaired by another repairman. Tear down the iPhone 6 to check out, we find both black and white touch were replaced, some capacitance under audio IC  get slight corrosion.  First measure the positive and negative 5.7V power supply to the ground value, +5.7V positive measurement is 400+, - 5.7V negative measurement is 600+, both are normal as shown in picture 3-7-1. We did not find obvious problems after ground value measurement, in accordance with the exclusion method, we firstly replace black touch, test failure is same, then replace the white touch, test failure still exist. It means there is no problem on IC, and also no obvious problem we can find from the power value. Thus, the fault point sh...

After white Apple logo displayed on iPhone 6 screen, iPhone 6 reboots automatically. And it reports unknown error (4005) when rooting. We can see from its motherboard that the solder pad has been soldered and there are jumped wires at logic NAND FLASH IC , as shown in the picture. Assemble board on testing assembly to root. Turn in on and connect it to computer. The i4 assistance says that iPhone is getting into DFU mode. After it is rooted, it reboots. Then it standbys until it reports unknown error (4005). Based on my experience, faulty NAND FLASH , CPU upper board and disconnected motherboard would cause such problems. Then I begin to fix them. First measure the diode data to ground of chip. The data is normal. After tearing the NAND FLASH, measure the diode data to ground that NAND FLASH use it to communicate with CPU. The data is normal too. Replace the NAND FLASH and root. The problem is still the same. Then solder CPU again to root. The problem is still the same. Tear th...

According to the description of our customer: iPhone 6s suddenly turns off when in use. After turning it on, it reboots itself after displaying white Apple logo. Use iTunes to root and it reports unknown error (4013). USB control chip  has been changed. Other parts are not fixed and it has not been dropped and gotten into water. How to diagnose this fault? After receiving it, turn it on to test. Screen shows recovery mode (also called data cable mode). Use iTunes to root and ascertain the problems. When the white Apple and grey progress bar show, the grey progress bar stops here, as shown in the picture. If iPhones 6S and its later series have such problem, the NAND Flash , CPU or baseband are damaged. Use i4 assistance' specialized function to root it and find the faulty place. When white Apple shows, the device UDID that i4 assistance reads are 0, as shown in the following picture. UDID exists in NAND Flash, so NAND Flash is faulty. And, the white Apple shows very quickly...

We get a iPhone 6 with the fault like this: sometimes it can enter into IOS, but reboots automatically all the time. Customer said: it was dropped. Occasionally, it reboots after getting into IOS for a few minutes. It reports unknown error (9) when rooting. How to fix iPhone 6 error (9) when rooting? The owner noticed that it often reboots automatically after entering into iOS, and when it is rooting, the unknown error (9) reported on the iPhone 6. Let's see what happened? I think iPhones is fixed, but when I get into IOS to test, the screen is blurred sometimes. Check display circuit and I find that display power supply PP5V7_LCM_AVDDH near display screen FPC socket  is abnormal. PP5V7_LCM_AVDDH is output by chip U1501 , as shown in the picture. At U1501’s peripheral capacitor C1569, I measure its output voltage. The voltage is normal. The location of C1569 on motherboard is shown in the picture. I do not find any voltage at C2071. U 1501 outputs PP5V7_LCM_AVDDH and transmit...

We got the iPhone 6 plus from one of our customers, he dropped it last month then cannot turned on it after using for few days. As she said, there is no important information and activation lock. so we root it and find that unknown error (9) reported on it. How to solve this problem? Let's take a look step by step. Use iTunes (or i4) assistance to root and it reports unknown error (9). Judging from my experience, NAND FLASH  or CPU problems could cause the error (9). First remove NAND FLASH and measure the diode data to ground, finding them normal. I suppose that the NAND FLASH itself is damaged. After I replacing a new one, the problem remains the same, so NAND FLASH is excluded. Next I check CPU . Customer said that it has been dropped. As for dropped iPhone 6 or iPhone 6 Plus, the solder pad that CPU uses it to connect logic eeprom chip  is easy to drop joints. Remove logic chip to measure the diode data. The location of logic chip is shown in the following pict...

We are going to fix the iPhone 6 plus with some faults, first problem it that we can't turn it on and the constant current is shown as 70mA. It was repaired before as its unresponsive touch. When soldering touch chip , the front camera socket dropped because the air gun had higher temperature. After soldering front Camera FPC Connector socket , I found that the front camera still could not be used. I blew the area near fingerprint socket. It cannot be turn on completely. Customer only sent the motherboard , so I energize it and test. The constant current is 70mA and it stops. Based on my experience, constant current stops at 70mA mainly because of the bus. I go on to measure the diode data of bus voltage. The data is normal. Many reasons can lead to turn on failure. If we want to narrow the problem scope, we can use root method. The customer agrees me to root. It reports unknown error (4005). Based on my experience, I know that CPU or temporary storage , as shown in the pictur...