Professional Cell Phone Repair Guide

Receive a iPhone 7, front camera can not work properly, but the rear camera, flash and other functions are normal. If your mobile phone is in the same situation, you should test the function first and then repair it. 1. First of all, enter in to the system to have a test. 2. Use iPhone 7 Plus opening tool kit to disassemble the mobile phone and remove the motherboard to test. We observed the repair traces of front camera J4503 base. It means the iPhone 7 Plus was repaired before. 3. There is no any problem when we use Fluke digital multimeter to measure the ground value, when measure the voltage of the 2 groups of I2C that were repaired: (R4810) I2C_NH_SCL_CONN and (4811) I2C_NH_SDA_CONN, we found R4811 resistance has no voltage, but it has value when trigger.   4. Now we can judge that R4811 is damaged. 5. Then we remove the incoming panel and replace the two pull-up resistors. 6. Repair is over here! If the article is useful for you, you can get more help from...

We received iPhone 8 from our customers, the problem was that iPhone 8P dropped before, then iPhone 8P was inserted into the SIM card and had no service. If we did not insert the SIM card, iPhone always prompted "no SIM card installation". How did this happen? Let's check the solutions in this article! For dropped iPhone, most of the iPhone pad pins are lost, or iPhone drops short circuited. IPhone 8 Plus was discarded before, so we suspected that the pad was dropped from the pin. After we untied the iPhone, we found that iPhone had been repaired by other maintenance personnel, and the DSMLLBYE and DSMHBHE chips on the iPhone motherboard had been removed. Use Fluke 15B+ Digital Multimeter   to measure the diode data for iPhone solder pad, we found the SCLK_HB_LB_DSM_FILT_E signal for the DSM_LB_E and DSM_HB_E IC is short-circuited. Open the WUXINJI Dongle  to check iPhone schematic diagram and bitmap, we found the previous repair man installed the R...

IPhone 6 needs our repair. The fault description is that the map application can locate, but not real-time navigation, and the location point can not update the mobile in real time. How to repair the common fault?   iPhone can be positioned, but the position coordinates of navigation are not moving. This fault may be caused by signal instability or GPS signal channel problem. First test iPhone 6, open the map application, navigation coordinates are not updated, and always in the same place. Disassemble the iPhone by phone opening tools , remove the iPhone motherboard. Open the WUXINJI Dongle  to check iPhone schematic diagram, the GPS signal through some switches to the U_WTR_RF RF IC and then to the iPhone baseband CPU, as shown in picture 18-2-1 Some small switches are covered by black glue, so we're not consider this factor first. Because it was first passed through the U_WTR_RF RF IC and then to the iPhone baseband CPU ， so we can replace a new U_WT...

We received a iPhone 6SP which reports error 4014 during recovery process. According to our past iPhone repair experience, we know that the 6S error 4014 was basically a NAND problem. How should we repair it step by step? 1. after getting the iPhone device, we connect it to the iTunes with lightning data cable, we find the white apple logo stuck on screen and then report error 4014 on progress bar. 2. use FLUKE multimeter to measure the power supply 1.8V and 3V  of NAND, both are normal. 3. remove the iPhone 6SP NAND to measure the resistance value of the solder pad. 4. it is found that the M6 pin abnormal, the normal resistance should be about 1000, but the pin value is infinite. Check the PCB pin and connect it to the external R1501 resistor.   5. After checking, we found that the resistor R1501 is missing, replace R1501, and install the NAND chip back. 6. use the iTunes to restore again, it no longer report error 4014, the iPhone 6SP can enters the system ...

Receiving a iPhone SE mobile phone, according to the maintenance experience, if the audio part of iPhone SE has some problems, can not work properly, for example, the iPhone SE audio part has no voice at all, or there is no voice from the other side at call. How should we repair it gradually?        First of all, we need to check iPhone SE schematic diagram on  WUXINJI Dongle , the iPhone SE audio part consists mainly of audio decoding U3500 and ringtone amplification U3700. There are three microphone, one is on the  iPhone tail plug flex cable , which is responsible for normal mode calls; One is on the  small camera flex cable , which is responsible for speaker mode calls; The last one is on the boot flex cable, which is responsible for recording function when take videos. The virtual welded or damaged audio decoding U3500 will cause calls without sound, leakage, large current or won't boot problems. So, if the iPhone SE no voice at a...

Are there any problems on the audio part of your iPhone? If you are cell phone repair professionals, you must know that the iPhone 5 audio part is composed of audio IC-U21 and ringtone amplifying U19. We need to figure out where to start repairing so we have to test carefully to the specific parts. Here we'll introduce the details in the article! The receiver signal RCVR_P RCVR_N in the normal call mode is sent out of U21 through the inductor FL51 FL52 and sent to the receiver flex cable interface J1. The inductance FL51 FL52 is easy to corrode and damage the receiver, which can be solved by short connection. The iPhone microphone signal is shown in picture 1, you can check on WUXINJI circuit diagram . iPhone 5 common audio fault is usually caused by water, resulting receiver function failure, inline corrosion or solder joint or FL51, FL52 pseudo soldering or shedding cause no receiver! Of course, before the repair we should first exclude the receiver flex cable is not ...

Have you ever had fingerprint problems on your cell phone? We are going to fix an iPhone 5s device with fingerprint part failure today. Before repairing, you need to know how to diagnose the real fault. First of all, check the iPhone 5S fingerprint schematic diagram by connecting  WUXINJI Dongle , there are  mainly three 3 sets of power supply circuits, they ware 1.8V, 3.0V and 16.5V, the 1.8V and 3.0V are available after booting. The 1.8V and 3V can be measured on the fingerprint socket  when press the iPhone power button, and the interface J7  can be measured. 16.5V can not be measured in peacetime. It can only be measured when fingers touch the iPhone Home button to add fingerprints or unlock iPhone with fingerprint. There are two cases of fingerprint failure, one is failed to open the "add fingerprint" icon, and the other one is "add fingerprint" icon can be opened, but it has no response when you touch the iPhone home button with your finger. ...

We are going to fix an iPhone 5 cell phone with charging failure today, as we know, the charging part of iPhone 5 is made up of Q2, U2 and U7. As shown in picture 1, the circuit diagram of the charging port J7 can be inquired on the WUXINJI dongle The 5V voltage sent from the tail plug passes through the Q2 to send two 5V power supply. PP5V0_USB_PROTECT and PP5V0_USB_RPROT were sent to U7 and U2 respectively. In addition, there are two detection pin in the middle of the battery contact J6! they pass through FL10, FL11 respectively and send to power IC-U7, FL10, FL11, in actual cell phone repair, it is found that the 2 pins are very easy to fall off, causing the cell phone can not be charged! and keep reboot again and again! If there is a problem of charging, plug in the data cable, use Flukedigital multimeter   to measure whether C304 has 5V output, and measure whether C272 has 5V output. If not, you need to test the iPhone 5 charging port flex cable , shor...

The iPhone 5S has a charging fault, such as the iPhone that can be charged when it is turning on, but it can't be charged when it turns off, or it doesn't support the accessory, or it can't be recharged at all. How to repair the charge failure on iPhone 5S? Let's have a look in the article! Check iPhone 5S circuit diagram on WUXINJI Dongle , we know that after plug the iPhone lightning cable, the charge voltage PP5V0_USB_PROT first passes through Q2, then to U2, and then to the iPhone power supply IC--U7, we can measure the voltage of 5V to U2 by Fluke 15B+ Digital Multimeter   at point C272, and the 5V voltage can be measured at point C304. If 5V cannot be measured at C304 and C32 points, this means that Q2 is damaged. In this case, we need a short connection to Q2, as shown in picture 1-1 below. If one has 5V and the other not, which means there is a disconnection. In this case, we will use QUICK 861DW  hot air rework station to solder a jump wire fr...

Blue screen reboot is a common problem for iPhone 5s device, for different users, there are also a lot of different reasons caused. In this article, we'll list 7 possible faults would happen on iPhone 5s device, hope it will help! 1. The screws in the red circles below are different from elsewhere. The screw holes below are empty, and the two screws below are motherboard. When you twist the screws, you will damage the iPhone motherboard immediately, it will cause White Apple logo stuck on screen and blue screen reboot, error 14 or 9. You need to especially pay attention to the two screws. It looks very strong and easy to misunderstand with big screws. The 5S motherboard can be easily damaged when many beginners  disassemble and assemble it. Remove the screwdriver with a HAKKO FX-951 soldering iron ! Gently scrape with the blade, you can see the broken wire! As shown in picture 2, you can connect it with a thin speaker wire. 2. U6 pseudo welding or damage would result...

Whether it is iPhone 5 or iPhone 5S, the camera problem is basically the power supply fault, which is caused by the corrosion and pseudo welding of the base, also the inductance of channel is corroded and fall off! The following picture 1 is the basic structure of the rear camera circuit. Let's take a look at the iPhone 5S power supply part shown in the WUXINJI circuit diagram .   For the L29, L30, L28, FL43 components, it is easy to cause no power supply after water corrosion, the problem can be solved by short connection, U210 and U13, the two small glass IC also easily damaged cause no voltage output, it can be short connected as picture 2.     Be careful not to use hot air gun to remove the U210 and U13, because the Baseband chip is next to them! If you remove it with a hot air gun, the baseband chip will short. First remove the black glue from the IC and heat with the HAKKO soldering iron . Let's take a look at the circuit diagram of the front camera...

Received an iPhone 5S with audio part problem from one of our customers, there are many different situations if the audio part get damage, how to fast test and repair it? Let's find answers from this article! As we know, the audio part is made of  iPhone audio IC   -U21 and ringtone amplification IC-U22. 1. If there is no sound on iPhone 5S, first we need to check whether every power on the U21 circuit is normal. If there is an abnormal voltage, we need to deal with it first; if all the voltages are working properly, then reinstall or replace U21. 2. If the receiver has no sound (normal call mode), replace the receiver and flexible cable, check the channel of the receiver, check the short connection of FL51 and FL 51, and reinstall or replace the audio U21. 3. If the other side can't hear your invoice during normal calling , replace the iPhone tail plug flex cable, check the microphone channel, check short connection FL49, check if C222 and C333 are dropped o...

If you have trouble to repair iPhone 5S won't turn on problem, the article will be a useful guide for you. Here we summarize the following situations for iPhone 5S won't turn on fault, hope it can help you. 1. Turn on with 50 Ma Current This situation is mostly iPhone CPU  or NAND pseudo welding or damage, which is very difficult to repair! Because the NAND chip can not be replaced alone, the cost of replacing CPU is also very expensive. And you can't make sure it will be 100% successful, so it is better to give up in this case. 2. Large current and won't boot  This situation is caused by short circuit in PP_BATT_VCC, PP_VCC_MAIN, the solution can reference to power leakage repair. 3. No leakage without turning on, large current when press the power button This is the case that the output of the power IC circuit is short circuited, you can measure the resistance of the output to the ground with  Flukedigital multimeter  one by one to find ...

iPhone charging failure is a common problem complained by users, we are going to repair a iPhone 6S device with abnormal charging fault today, the same problem as we encountered before. First we need to know its working principle. Open the WUXINJI circuit diagram , we can see that the PP5V0_USB (5.0V) sent from the charging flex cable is through the tail socket to the iPhone 6s charge IC, all the way through the protection tube Qx and send to USB control IC, as shown in picture 1: If there is a problem of abnormal charging: 1. Power is less and less while charging 2. It can not be charged in turn-off state 3. unrecognized USB, etc. Solution: First of all, use Fluke digital multimeter to measure whether there is 5.0V voltage (PP5V0_USB) next to the charge IC and the USB control IC. If these two 5.0V are available, then replace the charging IC and USB control IC. If there is 5.0V (PP5V0_USB) next to the charge IC (PP5V0_USB), but no 5V voltage next to USB control I...

We are going to fix an iPhone 6 device today. After turning on, the thermometer logo was shown on the screen, and "iPhone needs to cool down before you can use it" was reported. As shown in picture 17-13-1. How to repair this fault on iPhone 6? Let's check in the article! 1. Open and contract the WUXINJI circuit diagram , we use the regulated DC power supply to clamp the electricity for a test, we find the start current is normal, there is no leakage electricity or big current condition. 2. When we detect the thermistor, we find that the component is missing. 3. Apply some solder paste and use QUICK hot airstation  to disassemble a thermistor with same value from a discarded iPhone motherboard. 4. Observe the welded thermistor under LED Stereo Microscope . As shown in picture 17-3-2. 5. Now the iPhone screen does not show thermometer fault. Conclusion: Thermometer fault is caused by the following situations: When the thermistor i...

The water damaged iPhone 6 does not display after turning on. When the SIM card is inserted, iPhone 6 can receive calls from other phones, but there is no ringtone. According to our previous experience, because iPhone 6 has fallen into the water before, there should be one place that has been corroded causing abnormal display function. We can start repairing it from the damaged parts. Open the iPhone 6 device and take off the motherboard, then take it under the 14MP HDMI Camera Stereo Zoom Microscope   to observe the place where the water is flooded, we found the 2 4 pin of the J2019 display socket have been corroded.  Check iPhone schematic diagram on WUXINJI Dongle , the 2 pin is PP_LCM_BL_ANODE_CONN backlight power supply, 4 pin is PP_LCM_BL_CAT1_CONN backlight circuit. Carefully clean up the 2 pins, and then use QUICK 861DW  hot air rework station to solder, now the iPhone can display normally, but touch function doesn't work. After observation...

We received an iPhone 7 from customer, error 4013 is reported when reboot system in data cable mode. The most frequent problem on iPhone 7 devices is baseband part, which is often encountered by iPhone repair technicians. After 6S, if the baseband can't be identified, device will reboot with the white apple logo and not be able to enter the system. Maybe beginners will think that there is a problem with the Nand chip, no progress bar when restore system. If the baseband part is damaged, the error code can not be reported until 80%. But the iPhone 7 generation basically has a problem with the baseband. The repair process can be divided into the following steps: 1. Use Fluke digital multimeter to measure if the capacitance is short circuit to the ground? If yes, it can basically exclude and reboot, but the short circuit of the baseband CPU fault is 45%, the power failure is 45%, and the other 10% possibility is short circuit. Most of them are easy to fix except for CPU short ci...

  Water damage has always been a common problem on cell phones, we received an iPhone 6 device from one of our customers, according to his description, the cell phone won't Reboot after dropping into water, how do we deal with this common problem? After testing the iPhone 6, we found it cannot be charged, either, so our judgment is there are some problems on  iPhone motherboard ,   power part or iPhone CPU burn out. It seems that the iPhone logic board circuit is not damaged, so the iPhone 6 can be used after dropping into water. The reason that the iPhone 6 won't boot after using for a while is that the influent components are corroded. Use phone opening tools to disassemble it, and then connect  DC power supply   to measure the current, the current stuck on 76mA. Disassemble the iPhone display screen, and measure the boot current, we found the boot current is normal, and the iPhone can enter the IOS system.  We think the iPhone LCD A...