Professional Cell Phone Repair Guide

According to our customer's description, the iPhone 6 rear camera sometimes won't work, which has vertical line when take photos. According to our repair experience, first we measure the diode data of rear camera with Fluke 15B+ Digital Multimeter .   When we measure the diode data for the 34th pin, we found it unstable. Sometimes more than 300, sometimes more than 500 (The normal resistance is about 500). Open WUXINJIDongle  to check iPhone PCB schematic diagram, we know that this pin is 2.85 power supply pin. This 2.85 power supply pin is converted from U2301. Base on the above conclusions, we suspect that this could be caused by a 2.85V conversion tube virtual weld.  Gently shake the conversion tube with Precision Titanium Alloy Tweezers ; The conversion tube has fallen off. We can check it under the VGA Camera 7-45X TrinocularStereo Microscope . Now, replace a new conversion tube. And then turn on iPhone to test, now, when you turn ...

After getting the iPhone X motherboard to test, we observe the current value repeatedly jumps between 0mA and 50mA on DC power supply , and it is different from the normal booting current. Next, test whether the power supply of every circuit is normal. PP_VDD_MAIN is measured 4.2V; PP_VDD_BOOST measured is 4.2V. PP1V8-ALWAYS is 1.8V, all the values are normal. But when testing PP1V1_S2, PP0V8_SOC_FIXED_S1, PP1V8_S2 and other circuit voltage that output by power chip U2700 voltage are jumping constantly. According to previous experience, voltage jump is usually caused by a power supply circuit of U2700 output. Measured with digital multimeter , there is no short circuit was found for the dipole value of all power supply to ground. We repaired iPhone 7P before and know that if crystal oscillator is false welding can also cause voltage jumping, And if iPhone CPU  power supply is abnormal also can cause voltage jumping. Check the crystal oscillator we find no problem, then check th...

The iPhone 6SP was dropped down accidentally by its owner, there are various fault we need to repair today: iPhone rear camera , WiFi, audio, volume, photoreceptor, card setting. The heavy damaged iPhone 6S Plus is shown in picture 1-1-1. It can be turned on when using multimeter ( VC998) to trigger but the current is a bit large. No matter what, we have to turn on the handset and enter into system to have a test. The first problem is card setting. Continue to test other functions, it is true that the front flex cable, audio key flex cable, and rear camera are all broken, so we have to replace all of the spare parts. The last fault we need to confirm is motherboard: card setting, bad WiFi, audio recording is not available, bad audio and leakage. Triggered with more than 300 mA current, which means it has problem. Now we should solve the fault one by one. Since we can't get into the setup, so we take off the iPhone 6s Plus WiFi audio first. The result is the same. There...

Received an iPhone 6s with no display fault, which just show  black screen.  Before repairing it, we need to test and observe first. Let's check the detailed maintenance repair steps in this article! Disassemble the iPhone, use DC power supply  to provide power on it to detect it, the current is very normal. Even if the current it normal, but the iPhone screen still doesn't display. Observe it more carefully; we can see the faint light from the side, which means that this is faulty iPhone with a light but no display. According our experience, most of the fault points in this situation are in the display touch power supply circuit. Open the power side; we can see the iPhone PCB board  is very dirty, especially in the display touch power supply tube. And after check it, we can know that this display touch power supply tube has been replaced many times. Now we're going to use Fluke 15B+ Digital Multimeter   to measure positive and negative 5.7V on the ...

Received an iPhone 7 Plus with reboot failure, the owner wants us to fix it.  The original problem with this iPhone 7 Plus is that the iPhone touch screen  shows half bright half black after the boot, when repaired this problem, the iPhone 7 Plus won't turn on. Repair process After we received the iPhone 7 Plus, first of all, we need to use JM-P01 Essential Toolkit  to disassemble the iPhone, remove the iPhone motherboard and then put observe it under the VGA Camera 7-45X TrinocularStereo Microscope , there has traces of water, and many small original components have been torn down. Connect iPhone motherboard to the computer with C48 MFI USB Cable , there is no response. With the help of YH898D hot airgun  and tweezers, we remove the iPhone NAND Flash, and then connect it to computer again, still no response. Use Fluke 15B+ DigitalMultimeter   to measure the booting power supply and I2C bus, the data is normal. Now we start checking the d...

When the customer came to send the iPhone 6S device, he said: "the phone keeps rebooting repeatedly, it was repaired before, but still have not been repaired well by two mobile phone repair shops." After getting the phone, we carefully watched the mobile phone mainboard repair situation, and found that the barometer of the mobile phone was soldered with 4 or 5 jumper wires , but we have no idea what was the fault was fixed at that time. Observe the iPhone 6s motherboard with a professional TrinocularStereo Microscope  , it is found that there is a small dot near the barometer disappeared. Checking the WUXINJI   iPhone schematicdiagram  and bitmap, we get to know it is a zero ohm resistor.   After the short connection and installation, the iPhone 6s is tested OK. In order to ensure that the customer will not get any problems when he receives the handset, it will not be a problem if he wait for a night, until the second day morning, we foun...

According to customer's description,  his iPhone 6 device has been sent to two cell phone repair shop but didn't fix well. We can see much  solder flux  on WiFi module, so we can judge that it has been replace several times, and the resistor near to it is also lost , the copper wire can be seen on the bottom of Wife, so we can make sure it is not the iPhone 6 WIFI module  problem. First remove the WIFI and boot device to measure the voltage of WIFI bottom board pin, we find that 14 pin has no signal voltage, it should be 1.8V. The problem comes from here. Using a digital multimeter  to measure but no resistance, so we use WUXINJI bitmap  to check and find it is directly through CPU, is it the bottom board wire disconnection? It can be seen from the bitmap 10-25-1 that the iPhone 6 bottom board wire is really disconnected. Now we have to see if there is another way, continue to look at the principle diagram Apple 6. As shown in pictur...

The iPhone 6s problem is unable to turn on. Disassembling it by JM-9102 opening Tools , remove the iPhone motherboard and then measure it with Fluke 15B+ Digital Multimeter . When you press the power button there is a large current of 500mA, it is leakage and then won't turn on. After seeing the ammeter, the first thing we think about is not the iPhone battery voltage leakage, nor the power supply of VCC. After pressing the power button to appear large current is caused by the power supply load in the leakage or short circuit. First we use a Temperature-sensing method to feel the iPhone where the temperature is higher. After checking, we preliminary judgment the temperature is obviously high near the fingerprint line. Now we're going to check exactly which part is wrong. Through the soldered Rosin  method, we found that the 3D touch tube was obviously hot. This time we have an idea that this is not necessarily a problem with the power supply tube. When we fir...

Here we accept a iPhone 6 plus motherboard from a customer, the weak WiFi signal is the main problem. How to fix it with the best solution? You will find answer from the article! Repair process: Step 1. Install the iPhone 6P motherboard  to test WiFi signal. Obviously, It's weaker than a normal mobile phone. Step 2. Remove the motherboard to check, the WiFi connector circuit is not damaged, in many cases, most of repairmen would directly replace the iPhone WiFi IC  if WiFi itself gets damaged. Step 3. Since we have advanced equipment with VGA 7-45X Trinocular Stereo Microscope  to do careful observation, the motherboard is very beautiful, there is no water damage trace, the first consideration of fault is pressed parts. Step 4. Indeed, we can see the IC be pressed under the microscope , of course, do not first think that WiFi itself under pressure, sometimes the next filter will also suffer pressure. The following picture 10-4-3 is pressed IC fl_cell_rf wi...

The iPhone 7 problem is that won't turn on after water damage. No matter how many times you press the iPhone power button , it still does not respond, the iPhone has been kept black screen. How to get the best solution for the phenomenon?   After disassembling the iPhone by JM-9102 Disassemble Tools , we can see the mist in the iPhone, so we need to handle the mist first. After it is done, measure the iPhone with DC power supply , apply some power on iPhone, and then press the Power-on button to check the boot current, it shows large current. According to the curren t situation, this phenomenon should be the load of the power supply is short circuit. Now, we immediately use a method of feeling temperature to check, we found the lower part of the iPhone was hot. To narrow the scope, we can use the method of solder rosin  to check, we found that one of the reserve capacitors in the light boost circuit was shorted. With the help of YH898D hot air gun and Titanium A...

The iPad Air 2 we are going to fix today was started with water damage failure, a part of screen got unresponsive. After sending to a repairman, the screen becomes completely unresponsive, and it was still not fixed well by another repairman. After receiving the device, we can see both of the two white touches were damaged seriously. The iPad boostdiode  , black touch and electric tube had changed, and the touch screen was completely deformed. As shown in picture 12-7-1 , this white touch is the least damaged, so we replace the 2 serious damaged white touch first. This white touch is general with iPhone 6 white touch IC , so we replace it to test on iPad, the failure is still existing. Most of technicians must know that AIR2's black touch is a common trouble, so we begin to measure whether the black touch has a boost. The voltage is only 2.3V on the C4014 when measured with Fluke 15B+ digital multimer , and there should be a main power supply even if the voltage is...