Get reasons and solutions for iPhone 5S fingerprint failure issue

The iPhone 5S fingerprint function or touch ID not working, we need to repair iPhone fingerprint part.

First we need to check iPhone 5S fingerprint schematic diagram in WUXINJI Dongle, there are three 3 sets of power supply circuits mainly, they ware 1.8V, 3.0V and 16.5V, the 1.8V and 3.0V are available after booting.

When press the iPhone power button, the 1.8V and 3V can be measured on the fingerprint socket by Fluke 15B+ Digital Multimeter, and can be measured on the interface J7.

The 16.5V cannot be measured at ordinary times, it can only be measured when the finger touch the iPhone home button to add a fingerprint or when 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. The first case is caused by abnormal 1.8V or 3.0V or damaged iPhone home button, the second case is caused by abnormal 16.5V.

According to iPhone schematic diagram, we know that the FL33 easily corrode and cause 1.8V failure, and then causes iPhone fingerprint failure, we can fix it by short connecting. Furthermore, the U1700 is a 4 pin glass tube and it is easy to damage, so the 1.8V can't be outputted, and causes fingerprint addition failed, we can use tweezers to remove the U1700 and then short connect A1 and A2, as shown in picture 1-1. The 3.0V is supplied by iPhone power IC, iPhone power supply IC output 3.0V power supply PP3V0_NAVAJO via FL19 to interface J7, FL19 is easy to corrosion, and caused no 3.0V, so the iPhone fingerprint will be failed，we can fix it by short connection.

The 16.5V is supplied by U10, U10 output 16.5V power supply PP16V5_MESA via FL54 to iPhone tail plug flex cable J7.

FL54 is easy to corrosion and caused PP16.5V can't be sent to fingerprint interface, we can use QUICK 861DW hot air rework station to short connect it. U10 also is easy to damage; we can replace the U10 to fix it.

Get solution for iPhone 7 iTunes error 4013 (baseband CPU issue)

The iTunes reports unknown error 4013 on iPhone 7, after checking, we need to fix iPhone baseband CPU  parts. 

Before we are going to fix it, we will prepare some tools:

1. phone opening tools

2. digital multimeter

3. tweezers

4. hot air rework station

5. solder paste

6. High Temperature Resistant Tape

Now, start to repair.


Frist, disassemble the iPhone by phone opening tools, remove iPhone logic board.

Second, use Fluke 15B+ 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 the iPhone 7 CPU short circuit.

Third, if there is no short circuit parts, change the power supply and try to restore system again.

Fourth, if the above solutions are not effective, basically it means the baseband CPU has problem, you need to reweld baseband CPU. This is the baseband CPU pserdo soldering problem. Remove it with QUICK 861DW hot air station and reweld again. The baseband CPU of iPhone 7 is close to the main CPU. When it is removed, it should pay attention to protect with heat insulation tape, so that CPU can be flameproof.

Fifth, clean sollder pad and install the baseband CPU.

Finally, test the iPhone, now the iPhone 7 can be flashed smoothly, the iTunes error 4013 has been repaird.

Water-damaged iPhone 6 screen no display failure—How to fix?

A water damaged iPhone 6 touch screen no display after booting, when insert the SIM card, the iPhone 6 can receive the callings from other cell phone, but there is no ringtone on iPhone 6.

According to our experience, because the iPhone 6 has fell into water before, so there must be a corrosive place that causes display function to be abnormal. We can start the repairs from the water inlet area，so we can easy to fix it.

Disassemble the iPhone 6, take off the iPhone motherboard, and put it under the 14MP HDMI Camera Stereo Zoom Microscope to check 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.

Clean up these 2 pins, and then use QUICK 861DW hot air rework station to solder it well, now the iPhone has display after boot, but no touch.

Continue to repairing, after observation, we found that iPhone touch IC U2401 and U0900 audio IC all have water corrosion marks. Disassemble it to check, the solder pad have been corroded. Clean up the corrosive solder pad, and then replace the chips.

Assemble the iPhone to test, the touch function back to normal, there is the ringtone when receiving calls. The repairs end!

Solved: Water-Damaged iPhone 6S stuck on White Apple Logo after booting

The iPhone 6S fell into water, and then it stuck on white Apple logo after booting. It was repaired once before, when we received it, the iPhone 6S in white Apple status and it will be restarted occasionally. After remove the iPhone logic board, we found that the iPhone U2 IC and charge tube has been replaced.

Check the iPhone logic board under a 3.5X-90X Stereo Zoom Microscope 14MP HDMI Camera, there are small beads around the chip, which is a serious mistake. Clean up the iPhone logic board and then replace the new U2 IC and charge tube, but the problem still the same, iPhone stuck on white Apple logo and restart occasionally.

Use Fluke 15B+ Digital Multimeter to measure the diode data for iPhone battery detective pin, the data is normal, the resistance of iPhone booting condition is normal, and the voltage also is normal.

For the watered-iPhone, iPhone system is less damaged. After consulting with the customer, we start to flash iPhone. Connect iPhone to computer with iPhone lightning cable, the computer pop-up prompts that USB is not recognized. We suspect that the problem will be in the U2 circuit line. Take off the U2 to measure the resistance value.

After measurement, the U2 IC F4 pin PP3.0V_TRISTAR is short circuit, this point is connected to power and an inductor FL5408_RF next to an iPhone WIFI module IC, the U5411_RF receive amplifier is connected to the head of iPhone logic board. In order to find the problem point correctly, first we remove the FL5408_RF, measuring the ends of the inductor, we found a short circuit at the end of the amplifier.

 

Remove the two capacitors on the bottom, the problem still there. Remove the U5411 IC, and then measure it, the data is normal. The glue around this chip is very soft，use QUICK 861DW hot air rework station in 150 degree to remove it is enough, and please don't remove the capacitor next to it.

Finally, install the IC, re-weld the FL5408_RF, test iPhone and it can be turned on properly.