Professional Cell Phone Repair Guide

Received an iPhone 6 Plus from one of our customers, he described that the  iPhone 6P screen   gets black and nothing can be displayed. And the display chip part was repaired by another technician before. According to the previous phone repair experience, we think the fault is caused from the power supply. 1. Disassemble the iPhone 6 plus and take off the motherboard. 2.  Use  Fluke 15B+ digitalmultimeter  to m easure the iPhone 6P chip solder plate , all is going well.   3. After welding the display chip and install the screen to measure current, the booting current jumping is abnormal. 4. The backlight behind the screen is bright, +5.7V power supply is measured only about 2.2V, and -5.7V has no voltage . As show in picture 16-6-1 and picture 16-6-2. 5. We judge the display chip internal boost has some problem, and the WUXINJI dongle  circuit diagram shows that the capacitor C1554 energy storage booster capacitor is...

The customer mentioned that he failed to update iPhone 6 IOS system, it is in iTunes data cable mode when we get the phone. We are going to reflash it again by iTunes, when the progress bar reaches 80%, the iTunes reports unknown error 56, generally this error code means the fault is from camera power supply circuit and NFC. First of all, we are going to measure the iPhone camera circuit, it is normal. The issue of iPhone baseband CPU  we can put aside, if iTunes reports unknown error -1, and then we need to repair iPhone baseband CPU part. But this iPhone can be used normally before flashing, so maybe the NFC module is damaged; we are going to remove the U5301_RF first. Use  QUICK 861DW  hot air rework station to remove U5301_RF part, and measure the diode data for bottom pin circuit by multimeter, we found it is short circuit. Connect the WUIXNJI Dongle to check iPhone schematic diagram on computer, we found this circuit is connect to NFC power supply, ...

Got an iPhone 6 Plus from one of our customers, the main fault is described that the SIM cart can't be recognized. Why this happens? Let's learn how to test and repair it in detailed steps, hope it will help! Generally , the same fault is caused by damaged cell phone SIM card slot. First we are going to measure the SIM card slot to the ground value with digital multimeter . We found that the SIM card slot 1 pin PP_LDO5 is short circuit to the ground. Disassemble the iPhone with iPhone 6 Plus opening toolkit, check the iPhone 6 Plus bitmap on computer with  WUXINJI Dongle , it shows that PP_LDO5 is sent from the baseband power supply to the baseband CPU, SIM slot 1 pin, capacitor C3100_RF and the diode DZ3101_RF. It is not very likely that the base band CPU gets damaged, so we test by removing baseband power supply, it is still short circuited after that. Then we try to remove the capacitance C3100_RF, now the ground resistance is normal now. It seems that the prob...

Have you ever met the same phenomenon on your iPhone 6 Plus screen? A customer sent his iPhone, the problem is that the white Apple logo stuck on screen, and it's unable to enter into home page. How to repair the common problem? Let's fix it step by step in this article! Connect iPhone 6 Plus on DPS Digital DC Power Supply  to measure the booting current is jumping from 200mA to 1A, then it becomes a fixed current 300mA, based on our previous repair experience, we estimate it is mostly caused by USB, so we need to firstly check whether it can be online in recovery mode, so we connect the iPhone 6 Plus on computer and check by Ace assistant, the iPhone 6 Plus is not online. Opening the iPhone 6 Plus and remove the USB chip from motherboard, measure the booting current again, it is still jumping from 200mA, so we can judge it's not USB chip problem, it should be the problem of USB power supply. Measure the power supply grounding valure around USB by Fluke 15B+ digital...

If your cell phone gets the following faults like no voice can be heard when calling, no voice can be sent to the other side, no voice can be recorded, the phenomenon indicate that the audio components has some problems, in this article, we are going to repair damaged iPhone 7 and iPhone 7 Plus audio part. Read iPhone 7 schematic diagram on  WUXINJI Dongle  , we learn that the audio part consists of audio decoding and ringing amplification. And the ring tone amplifier IC also controls vibrator function. 1. No voice can be heard when calling When you have a cell on iPhone 7 or iPhone 7 Plus, you don't hear any voice. In this case, you need to firstly test the iPhone recording function. If the recording function is normal, but the call is abnormal, then the problem is basically in the iPhone baseband part. In order to repair it, put your iPhone on the WL Aluminum Alloy Pad , and then you need to disassemble the iPhone by phone opening tools, remove the iPhone m...

The receiver signal CODEC_TO_RCVR_N CODEC_TO_RCVR_P of the normal call mode comes out from the iPhone 6s audio IC , passes the FL3153 FL3154 to the receiver flex cable interface J3100, and then sends signal to the receiver to make a sound. There are two microphones in the normal call mode, one is LOWER MICI, the other one is LOWER MIC4. And there are two microphone signals, one is LOWERMICI_TO_CODEC_A1N1_P LOWERMICI_TO_CODEC_A1N1_N, and the other is LOWERMIC4_TO_CODEC_A1N2_P LOWERMIC4_TO_CODEC_A1N2_N. Read on WUXINJI dongle , we can get to know the two sets of microphone signals pass the charger port flex cable, charger port flex cable interface J4600, and then respectively through inductance FL4610 FL4611 and FL3613 FL4614 to Audio IC--U3500. The microscope power sent by audio respectively pass inductance FL4612 FL4615 and then through the charger port flex cable to supply the two microphones. Loudspeaker signal (ringtone signal) in the HF mode SPEAKER_TO_SPEAKERAMP_VSENSE_P ...

iPhone error code is very common for all iPhone devices. The iPhone 6 we are going to repair today also reports unknown error during data recovery process. Where is the problem caused from? How to diagnose and fix the problem, let's read in the article step by step! 1. We are going to root the iPhone 6, first of all, use  iPhone USB data cable to connect cell phone on computer,  the screen shows successful connection and directly enter into DFU mode. As shown in picture 15-12-1. 2. When it's proceeding in 20% by Ace assistant, the system stops to report error in FORTrueData file. 3. According to our previous iPhone repair experience, we estimate the main problem is from Logic chip or Nand flash chip. 4. Apply opening toolkit to disassemble the iPhone 6 and take off the main board carefully, we find the iPhone 6 Nand flash chip was operated before. There are much copper dropped out from it. As shown in Picture 15-12-2. 5. Remove Nand chip from main board by...

The iPhone 7 was dropped into water before, it's fixed before the phone gets in our shop. The main problems of the iPhone 7 are electronic leakage, no WiFi, No bluetooth, no vibrating, no ringtone, no camera, no flashlight and also there is stuck phenomenon. How to fix all of the above problems? Let's read in the article! All problems we mentioned have been repaired except for the iPhone stuck problem. we estimate it may be the software problem, so we use  iPhone lightning cable   to  connect on computer then used the iTunes software to restore iPhone directly. When the Flash process bar walks in 2/3 parts, iTunes reports an unknown error 56. Based on our repair experience, if iTunes reports error 56, it's  generally caused by NFC power supply and iPhone baseband   circuit part. Opening the iPhone 7 Plus and remove iPhone motherboard, take it to observe under the Phone Repair 7-45X Trinocular Stereo Zoom Microscope . Start to check from ...

According to our customer's description, his iPhone 6S Plus has problem with compass and screen flip function fault. In this article, we'are going to fix it step by step. If you are a professional iPhone repairman, hope the article will help you! Based on our experience, if the function of the compass is not normal, and the screen flip can not be used, this kind of fault is generally caused by damaged gyroscope chip or the chips on the connected SPI bus. As shown in picture 15-10-1. If the screen flip is abnormal, it will affect the function of the compass. How to Fix it After diagnosis? 1. Disassemble the iPhone 6S Plus by opening toolkit, we have to replace a new gyroscope chip with QUICK 861DW hot air station  at suitable temperature, you will also need to carefully take off it with a precision tweezers. However, it doesn't seem to be a problem of the gyroscope chip since the same problem still exists after that. 2. Remove the iPhone 6S Plus motherboard, t...

Water damage is unavoidable for most of cell phone owners, sometimes even if you are really careful, but the accident often happens, maybe you drop your cell phone into toilet, tank, cup, etc. It's very possible to happen like that. However, how to do if your iPhone 7 Plus drop into water and it's unable to turn on? In this article, you will get answer: Disassemble the iPhone to check circuit board; there are no obvious traces of water. And then remove all sockets, no traces of corrosion were found on the socket and the socket interface. Connect the iPhone 7P circuit board to DC power supply , supply power to it, it shows large current and won't boot. Check the iPhone 7P circuit board and observe under the 7-45X Trinocular Stereo Microscope , we found that both the capacitor and the main supply capacitor on the bottom of the iPhone motherboard to backlight are corroded. According to our experience, for iPhone 7 or iPhone 7 Plus, we can first check the first ro...

Received a iPhone 6 from one of our customers, according to his description, the device was working well and no any dropping or other damages. When he uses it like before, the iPhone screen suddenly doesn't display anything. What is the problem? Let's read in article. 1. Check iPhone 6 schematic diagram on WUXINJI Dongle , and then we know the iPhone 6 display socket circuit diagram.   2. Use Fluke15B+ Digital Multimeter  to measure the diode data of iPhone display touch socket, finding the 26 pin circuit is shorted; The display screen is positive 5.7V. 3. By reading iPhone schematic diagram, we know that this circuit is output by iPhone displaytouch IC , there are 6 filter capacitors on this circuit line. 4. Based on previous repair experience, we judged that the filter capacitors are damaged. Put iPhone motherboard under the Phone Repair 7-45X Trinocular Stereo Microscope , and then remove the filter capacitors one by one, when breaking into the third ...

iPhone camera failure is common for most of cell phone repair technicians, today, we're going to fix iPhone 7 Plus camera. According to the holder's description, the front small camera is normal while the rear camera fails to take photos, when turn on it, the iPhone 7 shows black screen. Let's start from easy repair operation: directly replace the iPhone camera to have a test.  Note: Pay attention that two camera are connected together. When disassemble the iPhone 7P rear camera , you need to pry up from the left side.  The fault is same as before after replacing a new rear camera. We tested before, the iPhone 7P double camera is rely on the bigger camera to get image, as shown in 15-5-1, the corresponding part on iPhone 7P motherboard is J4501 pin, the resistance value is normal after testing with Fluke 15B+ digital multimeter , it reminds of us that iPhone6 Plus also encountered this phenomenon, the power supply part has some problem. By checking on  WUXINJ...

Have you ever met the same situation on your iPhone 6? iPhone 6 charging failure is very common for cell phone repair professionals. However, there are many different reasons may cause this failure. In this article, we are going to fix the fault step by step, let's have a look how to solve it: 1. After taking off iPhone 6 screen, directly test the battery seat voltage B+ with   Fluke 15B+ Digital Multimeter , it is 0.46 V, there is no voltage can directly exclude the battery problem. 2. Test battery seat resistance B+385 (abnormal resistance will cause white apple restart symptom) normal, disassemble the single board test the 5V sent by USB. There is a test point below the battery interface. If there is 5V, it means there is no problem with the tail plug flex cable(if not, then replace a new tail plug flex cable to test again). Now we are continue to test the IC with failure 3. Use multimeter to measure whether the capacitance C1704, C1408 has 5V voltage, if neither of them ha...

We are going to fix iPhone 6 with WiFi failure in this article, the mobile phone is, according to customer's description, when enter the setup page, the phone will get stuck. In addition,  when check the WiFi function on shortcut, WiFi is not able to turn on. How to solve the problem? The mobile phone is disconnected, now measure the status with DC power supply . It is found that the current jump is normal, and there is no case of large current. After the removal of motherboard, After the inspection under trinocular stereo microscope , we find that the iPhone WiFi chip was replaced before. Remove the chip first, because the last repairman had changed the WiFi chip, and there was no large current when turning on, so it was initially not the problem of the chip.The 13 pin of the solder pad is measured infinite (normal resistance more than 400). The signal passes through the resistance R0711 to the CPU, and the resistance R0711 is found to have a resistance, and it seems not t...