Professional Cell Phone Repair Guide

The iPhone 6 fault is that the touch can't work completely, it should be iPhone white touch IC problem. After removing the motherboard, we found the iPhone black and white touch IC have been replaced by former repair man. Measure the working condition for iPhone black and white touch IC, and measure the 5.1V and 1.8V of the iPhone white touch IC .  The iPhone black touch IC +5.7V -5.7V and 1.8V power supply. After measure them with digital multimeter , all the data tested is normal. Remove the iPhone black and white touch IC, and then measure the diode data for the solder pad, it is normal. Based on previous maintenance experience, we know that the inductance of the iPhone 6 plus the display socket synchronization signal is easy to be null welded and causes the iPhone to not touch at all. The measured value of the socket synchronization signal in iPhone 6 is about 400, which is normal. With this fix in mind, we replaced the new U2403 touch sync tube and then...

When are going to repair a iPhone 6S today, the problem is that when we test with DC power supply , the current value is shown as picture 1. It's large current, how should we repair it? Let's check in the article! 1. According to our past phone repair experience, there is no obvious corrosion or serious pressure on the motherboard, so we first test the motherboard PP3V0, USB and NAND power supply. 2. In the maintenance process, if you encounter the same situation:  the motherboard is large current and also can be turned on, if the motherboard and above several circuit PP3V0 are all normal, you can first install the iPhone to test function, if all the function is normal, then your lips can be touched to test whether the temperature of USB is heating, the iPhone 6S motherboard  we test through the lips, it is found the USB is extreme heating, so it is determined that the USB causes large current. 3. As shown in picture 3, the current is normal after removing the US...

The iPhone 7 enters into iTunes mode and reports error 4013 after reflashing by the customer, he did that because of signal problem, for this kind of fault, we need to detect the baseband first, if there is a problem in the baseband, do not reflash iPhone, or it will gets error fault (error 4013, -1 will be reported when the progress bar goes to the 60% or 80% position ). We found there is a problem in the iPhone baseband. Since the iPhone is in iTunes data cable mode, we can't measure the voltage, so use Fluke digital multimer to check whether the resistance of each circuit of baseband power supply is normal. The test points of each circuit can be found more accurately based on the WUXINJI schematic diagram , and the corresponding components can be found on the bitmap for testing. The resistance of baseband power PP_VSW_S4 is only 45, but the normal resistance value should be more than 500. This circuit is connected to main power supply, base band power supply, small ra...

iPhone 6 is directly connected to the DC power supply after short circuit, large current short circuit and iPhone motherboard overheating. We think this is a small problem. When we remove the iPhone, we find that the iPhone charging tube is hot. Remove the shield and apply some rosin. Obviously, the iPhone baseband power supply is damaged. Delete the iPhone baseband power, then connect the iPhone logic to the DC power, the iPhone start, but not display, more clearly check, several pins on the socket are damaged.   Remove the socket and clean the pads, re solder the socket. After replacement, iPhone can be turned on normally, but there is no baseband. Install the new iPhone baseband power supply, but there is no SIM card failure, continue to measure it, and no front and rear cameras. IPhone 6 no front and rear cameras are usually caused by a 2.85 volt power supply. A regulated converter is found directly. Scrape off the glue and weld the jumper. We can check the bitm...

Customers said the iPhone 6 can be turned on, but the screen is black and not bright, he can have calls normally, also, the iPhone is able to connect to Ace assistant. According to his description, mobile phones can be turned on, connect to computers and make phone calls. It seems that problems appear on the iPhone 6 display or backlight. Disassemble the phone and connect adjustable DC power supply , it is found electricity leakage, there is no back light after turning on, but with the light we can see the apple Logo. Remove the iPhone main board, we found there are water corrosion marks. Observe under a Trinocular Stereo Microscope , as shown in picture 19-6-1. Pry out the corroded components, remove the backlight chip, two stage tube, backlight boost inductor, and connect the adjustable power supply, it is without leakage this time. welding back the backlight chip, boost diode and boost inductor. Reassemble the screen and turn the iPhone 6 on to have a test, it is fou...

Phone 6 Plus touch M1, iPhone 6 baseband u1v1 and iPhone 7 audio problems are very common for phone repairmen. At first, we can weld  iPhone touch IC  or re-install touch IC to fix iPhone 6P touch problem, but after a while it need to be repaired again. Later, we figure out that we can repair the problem by   jump wire . The baseband u1v1 and audio problems can also be used in the same way. The first layer of these iPhone motherboard layer circuit lines is very fragile and easy to disconnect or virtual welding, some are not broken by the naked eye, but in fact it is almost disconnected, weak links, at a critical point. Now, let's back to iPhone 7 baseband problem, most people think it is Qualcomm baseband problem, and we think it's still the same as before, it's iPhone motherboard design flaws.  Check the working schematic diagram of the iPhone baseband power supply through WUXINJI Dongle , it's amazing, as shown in picture 1. Put iPhone 7 and ...

After iPhone 7 Plus is inserted into the SIM card, the search state is displayed all the time, and there is no IMEI at dialing 06. Check the settings on iPhone with IM and Modem firmware numbers. After reset, the problem of iPhone network setup still exists. If you encounter the same fault, don't flash the iPhone first, if the iPhone baseband CPU  has some problem, then it will report unknown error 4013 on iPhone 6S and above, for 7 and 7P , we need to notice iPhone baseband 1.0V power supply circuit. If iPhone baseband power supply is short circuit, then basically it's caused by damaged iPhone CPU, so we need to measure the resistance for this circuit before we start to repair. For an iPhone with an iTunes 4013 error, we can heat iPhone baseband power, and then flash it. Insert the WUXINJI Dongle   on computer , and then compare with the iPhone schematic diagram and iPhone motherboard bitmap to measure the iPhone circuit line power supply. After measurement, a...

Customer sent a iPhone 6S Plus, describes the fault is the phone screen is half black, after analysis we get to know that such a fault is generally a backlight circuit problem. The last repairman described the iPhone motherboard has connected tin, so there was no direct test on DC power supply . Disassemble the iPhone 6s Plus and observe the main board under LED Stereo Microscope , we find there is connected tin in the fingerprint base. After cleaning up the board, we connect power supply to have a test, it is found that the fault is the half black screen, which is consistent with the customer description. When use Fluke digital multimeter  to measure the ground value of the iPhone touch base , it shows that the 6 pin of the display base are infinitely large, indicating that the pin is broken. 6 pin is backlight power supply, which is through the FL4211 inductor to the backlight chip, since the FL4211 inductor plate has been destroyed by the last repairman, we can not...

According to the customer's description, the iPhone X would not turn on after it drop accidentally. Then the cell phone reports error 56 when restore it. How did this happen? Let's test and repair step by step. Since iPhone X motherboard 2 layers are connected through the middle column, the solder points are very easy to get dropped. so we guess that the solder points from NFC chip to the CPU part have fell off. Disassemble the iPhone X by iPhone opening tools , remove the upper board off the main board, when separate the main board we see there is a row of points have fell off. Check the location map on WUXINJI dongle , it is surrounded by a ground wire, in fact, there are 6 useful points dropped. The ground wire does not need to be filled, the 6 useful points are added by professional phone welding tools. These are the signal wires of the NFC chip, so the iPhone X would report error 56. Then the tin of the middle column is repaired by iPhone X BGA reballing ste...

iPhone 6 does not display after starting, first connect it to the DPS DC power to check the current, the iPhone boot current test is normal, iPhone 6 turns on but the screen is not displayed. How shall we repair it? Remove and observe the iPhone logic board under the Stereo Zoom Microscope , we find the iPhone Nand flash has been repaired before, and other parts not. However, because the iPhone Nand flash has nothing to do with the display, so we can ignore this problem. Measure the resistance value for display socket by digital multimeter , we find the all resistance value is normal. Since the resistance is normal, then we need to measure the display power supply. Install the iPhone display screen and test it, the display +5.7V and -5.7V all are normal, but when measuring the 1.8V voltage of the display reset, no voltage was found. After checking iPhone schematic diagram on the WUXINJI Dongle , we know that the display reset signal is directly provided by CP...

Got a iPhone 6 Plus from one of our customers, the main fault is that the front camera and distance sensor can't work normally now. Which part get damaged? how can we repair the 2 functions well? Let's check in this article! According to past experience, these two faults are generally concentrated on the flex cable of the front camera, which may be caused by wire damage. First of all, we need to eliminate the possibility of external components failure, and then consider the motherboard problem. After removing the screen component and replacing a new one, we are still unable to open the front camera and use the distance sensor. Disassemble to measure the ground resistance of the front camera seat of J1111 by Fluke digital multimeter , it is found that several pins are infinitely large, and the related inductors are loose when touch with the pen. It seems that the small components are pseudo welded. Remove the motherboard and observe it under the Trinocular...

We are going to fix a iPhone 7 with blurred screen. How shall we step and repair the common problem step by step? Let's have a look in the article. After receiving the cell phone, what we need to do first is to test it and confirm the fault. Disassemble the phone with iPhone 7 opening tools  carefully and observe the main board. We found this motherboard is a pretty board, according to the previous maintenance experience, the iPhone display base needs to have a test with Fluke digital multimeter . It is found that the resistance of the 17th pin showing the J4502 resistance of the base is infinite, and the normal resistance should be more than 400. This pin is powered by the screen 1.8V. This point is connected with the inductance DL3906 through reading on WUXINJI schematic diagram . The other end of the inductance is measured normally, so we replace a new inductance FL3906. Reinstall the iPhone 7 to have a test, failure is solved perfect now! Any other professiona...

The iPhone 6S we are going to fix has no display after turning on, it accidentally dropped into water before, after drying it, we press the iPhone power button, after for a while, the screen still is black, we try to use another iPhone to call it, the phone has response, but the iPhone screen  still doesn't display. How to repair this kind of fault? Disassemble the iPhone 6S by phone opening tools, and carefully remove the iPhone logic board.  Connect iPhone to the DC power supply  to measure its starting current, the current tested is normal, no large current failure, now we need to check if it has a display but no backlight. Check it under the light, we find the iPhone has a display. Use Fluke 15B+ Digital Multimeter   to measure the display socket, s ome pins are corroded, but the resistance value data  is tested normal. We need to take off the CPU shield, we found that one end of this capacitor was seriously corroded. Check iPhone schemat...

Received a iPhone 6P phone from one of our customers, he described that the main fault as the following: When connect the iPhone motherboard with DC power supply , the current is normal,after installing the screen to test, there are no lights and no display. According to the customer's description, it is inferred that it sometimes displays and sometimes does not display.  By observing the appearance of the motherboard, we can not directly determine the fault point, the measurement of the display base resistance to the ground and power supply are normal, after the replacement of display IC U1501, the iPhone 6P is still not displayed. In view of the fact that the 6P motherboard is easy to get broken by pressure or false welded , we have to remove the U1501 and use Fluke digital multimeter  to measure the pin resistance. Fortunately, when the B2 pin is measured no resistance, we know the fault is finally found. The B2 pin was supplied by the PP VCC MAIN through the booste...

We are going to fix an iPhone 7 Plus today, the problem is that the iPhone 7 Plus front camera not working. How to fast fix the fault? Let's read the detailed steps in the article! After we receive iPhone 7 Plus, we will test it first. Open iPhone 7 Plus, enter iOS, open the iPhone camera icon, iPhone rear camera normal, switch to iPhone front camera, iPhone 7 plus front camera do not work, display black. Untie iPhone 7 plus the phone opening tool, and carefully remove the iPhone motherboard. Put the iPhone main board on the WL aluminum alloy pad. Measure the ground resistance for iPhone front camera socket J4503 by Fluke 15B+ DigitalMultimeter , the data tested is normal. And then measure the iPhone front camera power supply, the data tested also is normal. However, when we measure the I2C bus, we find the voltage for I2C_NH_SCL_CONN only have 0.62V, which is abnormal. After check the iPhone 7 Plus schematic diagram in the WUXINJI Dongle , we need to replace ...