Professional Cell Phone Repair Guide

We find current 80mA circularly run while connecting and triggering with multimeter , so maybe it's USB damgage cause I2C short circuit during charging process, first remove the iPhone 6 motherboard  and take the USB off, but it's still the same as before, then we measure the I2C resistance and power supply! It is found that the I2C 0SCL is in a short circuit state. As shown in picture 11-10-1. Since it's short circuit, it means the connected chip is damaged, the connected chips have display, backlight, main power supply USB and the iPhone 6 CPU . First observe with microscope , it is found that all the backlight diodes are burning and discoloring. Then remove the backlight first, it does not short-circuit. The trigger current is normal, so continue to replace the 3 piece of iPhone backlight chips . According to our past experience, if the large inductors gets discoloring, the large inductors with connected backlight would also have problems, so we replace them togeth

We received an iPhone 6 Plus with some faults. According to customer's description, the iPhone 6 Plus LCD screen  has no display and no light, it has changed the kit before. How to solve the faults? We need to solve this problem step by step. 1. Measure the working condition of iPhone LCD display IC , all is normal. Then measure the display socket J2019 with Fluke 15B+ Digital Multimeter , we found the #3 pin is short circuit. 90_AP_TO_LCM_MIPI_DATA3_N MIPI image transfer data bus leads directly to CPU, the initial diagnosis is that the CPU is continuous tin or internal damage. 2. Remove iPhone CPU  and then measure this signal line, we found it is the earthing short circuit, which is CPU internal damage, the kit is damaged. 6P and 6 are not the same size; the circuit design is also not the same. By analyzing the WUXINJI schematic diagram , we found the solution. 3. According to the comparison of WUXINJI schematic diagram, we found that iPhone 6 Plus has one more

According to our phone fix experience, if a cell phone device is tested as 200mA electric leakage when booting, we generally choose to replace USB tube. However, this is not absolute, the iPhone 6 we received is not caused by USB tube fault. Connecting the iPhone 6 with  multimeter , the current shows 200mA. we directly replace a USB tube. The result is that the current is still in the 200mA position after waiting for a few minutes. So we wonder if there is another fault symptom happened, the last repair technician mentioned the  iPhone 6 fingerprint  is not good. When heard of this problem, we can basically judge where the problem is. Connecting multimeter and trigger the switch current with 300-400 mA, this is not normal. There must be something wrong with the fingerprint 3V. Use the multimeter to test fingerprint 3V against the ground value, it is short. This kind of situation is generally caused by one of outside capacitance is short, dismantling it! Finally, we fi

Received a customer's iPhone 6, according to his description, the fault is that the sensor can't be used, and the iPhone 6 battery  power consumes very fast.  How to fix the faults? First we need to connect DC power supply  to have a test. Repair process: Disassemble to connect power supply, which is normal with standby mode, when turn on the iPhone 6, it's found that the current jumps from 300mA, the normal current should be from 80mA. As shown in picture 11-7-1. Customers said that the phone is not black screen, the flex cable was replaced before but the failure is still existing, it seems that the fault is from sensor. Take out the universal multimeter to measure iPhone 6 motherboard . As shown in picture 11-7-2. When testing 3V power supply on sensor, plate is short circuited to the ground, the power supply goes out of the PMU to the J1111 interface, with a series of capacitors in the middle. The capacitance is distributed in three places: near J1111, the

Received an iPhone 6 Plus, first we need to know the basic information about the device. According to the customer's description: 1. the iPhone touch function can not be used; 2. there is very important data in the iPhone so that we need to pay attention not to restore the device. Repair Process: 1. The failure is that the touch can not be used, we still follow the rule: easy operation first, first replace the iPhone screen , the touch is still no working. 2. After excluding the screen problem, we judge it's iPhone motherboard  problem. 3. Remove the motherboard and connect to measure touch voltage, PP5V7_SAGE_AVDDH touch +5.7V is normal, PP5V7_SAGE_AVDDH touch the -5.7V voltage has no value. As shown in 11-5-1 . 4. The other points are found to be normal, power off to test whole circuit, we find circuit line is broken. 5. Soldering the broken line with jumper , connect the 2 points in iPhone diagram with jumper wire as shown in picture 11-5-3 , a

Received an iPhone 6 Plus with speaker problem, there is no sound on speaker when the owner receives a call or play music. How to solve this problem? This article will help you! Diagnosis Process: 1. Check the current and voltage between the iPhone tail plug  and audio 2. Replace the iPhone audio IC 3. Check the line from audio to iPhone CPU to see if it is normal Repair Process: 1. Use JM-9102 Disassemble Tools  to replace the iPhone rear shell assembly, and then test it, the fault still exists. 2. Use Fluke 15B+ multimeter to measure the resistance value from tail plug socket to small audio, all is normal. 3. Remove the small audio and then measure the line from small audio to iPhone A8 CPU . After measuring the diode data of SPKAMP_RESET_L, we found its data showed infinity, it may be caused by the disconnection or CPU virtual welding. In this step, WUXINJI schematic diagram will help you a lot. ​ ​ ​ ​ 4. After communicating with the customer

iPhone 6 can be turned on and receive calls, but the screen doesn't display, and we replace it before opening the screen. The appearance is not very damaged, replacing a new iPhone 6 Plus screen to test, it still has no display and no backlight. The measurement of display connection resistance is shown in picture 11-2-1. The measured value is completely normal, there is no current burnt traces on the iPhone backlight chip and display  power supply IC , so we can start to work on its display part. Taking off the display IC under good protection, and work on solder pad with low temperature solder, do not rush to replace the new IC, the bottom resistance should be measured before that. As shown in picture 11-2-2. The result shows that the D3 pin I2C bus CPU has no resistance to the clock signal of the display power, and the C3 display has no resistance to the power IC signal. According to these two results, we can make sure that the lock screw is wrongly installed to cause the motherb

Got an iPhone 6 with virious screen images after booting, the backlight is getting darker and darker. When we received it and check it, it's not dropped and water damaged. We judge the fault is in the iPhone screen  circuit and the touch circuit (sometimes a zebra stripe appears after booting), as shown in picture 11-1-1. According to the common problems, directly replace the U2402 deputy touch IC and U1501 screen power supply IC , the fault still exists. We have to repair it step by step, now we open the WUXINJI circuit diagram, as shown in picture 11-1-2. Use Fluke 15B+ Digital Multimeter to measure the J2019 screen connector socket power supply, reset, open and bus, all data is normal. Then we try to remove the U2402, but the problem still the same, the repairs falling into slow rhythm. Remove the U1501 screen power supply IC, and measure the diode data of power supply, reset, I2CO bus, all is normal, directly replace it, the problem still the same. The repairs again tur

We are going to fix an damaged iPhone 6sp without touch function, the faulty  iPhone 6sp motherboard  is shown in picture 5-1. How to get the best solution for the touch fault? Fault Detection : First observed the iPhone 6SP main board appearance after getting it, we can see it has slight water influent, but no obvious corrosion, also there is no obvious deformation on the board. Fault Repair: 1. According to our repair experience, the first step is to measure resistance value with multimeter , we find there is no resistance value displayed on J4200-22 pin, so the fault of we are going to solve today is found out now. As shown in picture 5-2. 2. After removing glue on the main board, it is found that FL4215 falls off, as shown in picture 5-3. 3. How to solve the fault? just directly short connect FL4251, the resistance value is tested normal. 4. Now continue to install the iPhone 6sp screen  and have a test, touch function finally gets normal.

Received a broken iPhone 7 and a iPhone 7 with ID lock, according to his description, the damaged iPhone 7 has no ID lock, but it unable to boot. The customer wants us to fix it, and then move it to the iPhone which with iCloud lock. But now, we need to fix the damaged iPhone first. After checking, the iPhone is hurting a lot by a serious drop. The screws  on motherboard have been dumped, as shown in picture 6-3-1. Connect it to UD 1505TA DC power supply  first, it shows large current leakage. After measuring, we found the iPhone NAND flash  3V power supply was short circuit. After observation, we found the iPhone motherboard slot position is bent; the short circuit may also be in this position. After remove the two capacitors, which on the side of the NAND flash, detecting it again with DC power supply, now it can be turn on normally. Turn on iPhone and test functions on iPhone, we found there is no WIFI; sometimes it will be stuck when into the settings. After measuring

We received a customer's iPad Air2 device (4G version) today, the owner said that the 4G version ID account is forgotten by him, the only solution for the situation is to change the 4G version into WiFi version. For iPad Air 2 (4G version) device, it can be easy to change to the WiFi version as long as it is right to fill the iPad R0505 resistor on the GPIO_BRD_ID2 signal. R0505 resistor part is shown in iPad schematic diagrams  as following: Flash WiFi version firmware, if it's processing normally, WiFi will not be used. There are WiFi address on the iPad but can not open, it will become gray when opening the WiFi sign. In front of this kind of situation, we need to replaced a iPad WiFi chip  called 339S0251, so that it can be used normally, original WiFi as shown in Picture 10-13-5. After the replacement of WiFi, as shown in Picture 10-13-6 Install to test the iPad device, it works all normal, repairs are ended here now! More cell phone repair tutoria