Best Solution--iPhone 6 camera get stuck when turn it on

A customer sent an iPhone 6 to us to repair, the fault described is that the iPhone 6 rear camera sometimes won't turn on, and there is a vertical bar when take photos. According the 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 WUXINJI Dongle 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 on the camera, it won't get stuck. The iPhone rear camera can be turned on smoothly.

iTunes error 4014 on iPhone 6S—How to fix?

The customer sent us an iPhone 6s needs to be repaired, the fault described is that it reports unknown error 4014 when flash it. After detecting, the current is 57mA, DFU mode, flashing it and it reports 4014, which is consistent with customer description.

Disassemble it to check the iPhone motherboard, the iPhone Nand flash on this motherboard has been repaired, and when check it under the microscope, we can see that the iPhone NAND flash damaged.

Remove the iPhone Nand flash and measure its diode data, it is normal. Put Nand flash into the WL PCIE Nand test programmer to test it, unsurprisingly, the NAND flash is damaged.

Replace the new iPhone Nand flash and flash it again, the fault still exists. As we know, the iPhone 6S and later iPhone reports iTunes error 4014 mostly caused by nand flash and baseband issues. However, after measuring, we know that the iPhone Nand flash is good, so now the problem is iPhone baseband. Measure the diode data of baseband power LDO part and S1-S5 power supply, all is normal.

Flash it again, test the S2 and S4 when the White Apple logo appears, there is no power in either of these places. Since S2 and S4 have no power, it is possible that the baseband power supply does not work and then can't output power. Remove the baseband power, and then use Fluke 15B+ Digital Multimeter to measure it, we found the 55 pin is to ground.

55 Pin connected to the 19.2M clock, put iPhone motherboard under the VGA Camera 7-45X Trinocular Stereo Microscope to observe the 19.2M clock.

19.2M clock with C3501_RF capacitor grounding end connected together

Handle the baseband clock well, and then flash it again, now the progress bar can run normally, and iTunes doesn't report unknown error 4014 anymore.

Here! Get solution for iPad Air 2 touch function unavailable issue

 Received an iPad Air 2 to repair, its problem is the iPad Air 2 screen completely unavailable after water damaged. It was sent it to repair once, but not working. You can get solution here!

After receiving the device, we can see both of the two white touches were damaged seriously. The iPad boost diode, black touch and electric tube had changed, and the touch screen was completely deformed. 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 not boosted. Measuring the inductor L4001 we find that the voltage was different. Taking off the inductor to test, it is the original inductance was burned.

Replacing the inductor L4001, check the diode D4001 is not damaged, continue to test the device and find that there is still no boost out, this place should have a boost even if no LCD installed. The inductor diodes are checked in the three large parts of the boost, only the black touch itself does not work will cause no boost. The last repairman has changed the black touch, now we can only change the black touch first. After changing the black touch, it is still the same as not to boost. so we can continue to check the working conditions of the black touch, opening WUXINJI Dongle to check.

Both black touch power supply have value: 5.25V and 1.8V  .

The power supply of the 12C bus is normal.

It is found that the black touch EN signal comes from the white touch U4150. Is it the replaced white touch problem? Before replacing the U4150 touch, first checking the U4150 and find there is something lost, after checking diagram, we get to know it is the resistance U4154.

Through the original factory diagram, it can be found that the R4154 is the touch clock frequency pull-down resistor. According to the usual maintenance idea, it is learned that one end of the chip is grounded, and the pull-down resistor must not drop, similar to the REXT resistance in iPhone.

A resistance of 4.7K was found on the iPhone motherboard, and boot to test there is boosted out, and 18-20V. 

Finally, install the iPad screen to test, now the iPad Air 2 touch function is back to normal,  you can touch it randomly, it works perfectly!

Solved: iPhone 6s no display fault (C4002 damaged)

A customer sent us an iPhone 6S to repair, the fault is that the iPhone 6S no display, it just shows black screen.  After we received the iPhone 6s, we start to repair.

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 iPhone display touch power supply tube, the voltage measured is less than 2V. Next to measure the voltage of boost capacitor, the voltage only is less than 2V. Now we know the boost circuit is a problem.

Because the display touch power supply tube has been replaced on iPhone 6S, so we don't need to replace it now, the emphasis is on boosting inductance and capacitance. After measuring the inductance, we found that it was no problem. Then the problem is centered on the capacitor.

Open WUXINJI Dongle to check iPhone schematic diagram, we know this boost capacitance is C4002, we decided to replace the capacitor. With the help of QUICK 861DW, we replace it smoothly and quickly.

Assemble the iPhone to test, the screen displays normally now. Continue to test other functions, all is fine, the fault has been solved. The fault is on this small capacitor.