How to fix iPhone 6 black screen/WIFI/volume button failures?

The iPhone 6 has black screen, WIFI cannot be recognized, volume button not working issues after replace the iPhone display screen, how to fix?

Disassemble the iPhone by phone opening tools, and then remove the iPhone motherboard.

Meassure the diode data for display socket J2019 with Fluke 15B+ Digital Multimeter, we find the diode data for 14 pin AP_TO_LCM_RESET_CONN_L is infinitely large, which is disconnected.

Put iPhone motherboard under the Stereo Zoom Microscope to check , we can see that there is the trace of a breakdown for left screw column BS2502,  scrap it and re-connect the disconnection. Measure the resistance value to grounding for display socket J2019 14 pin AP_TO_LCM_RESET_CONN_L with multimeter, the data is normal.

Install the iPhone and test it, we find the iPhone volume button not working, and the WIFI cannot be recognized.

Measure the resistance value to grounding for iPhone volume button socket J0802, it is infinitely large, and perhaps it is disconnection. This circuit line is on the third floor of the left screw column that near the edge position, carefully scrape it and then re-connect it.

There are 2 reasons causes the WIFI cannot be recognized, one is the iPhone motherboard disconnection, and the other one is iPhone WIFI module IC problem. Remove the iPhone WIFI module IC and measure the resistance value to grounding for solder pad, no abnormal was found. Replace the new iPhone WIFI module IC, and then measure it agian, seems all data are normal now.

Finally, install the iPhone and turn on iPhone 6 to test, the iPhone display screen works fine,  test the iPhone volume button, it works properly, test iPhone WIFI, also works good. All failures has been fixed, the iPhone 6 back to normal work.

Dropped iPhone 6 no fingerprint—How to fix ?

A dropped iPhone，the iPhone display screen has been replaced, after using for a while, the customer feedback that the fingerprint unlock function can't be used. Check fingerprint on the Settings, it prompts that "Failed, Unable to complete touch ID setup, please go back and try again".

Use Fluke 15B+ Digital Multimeter to measure the resistance value for fingerprint socket, all is normal. Replace the fingerprint connector flex cable, we found a tear mark on the iPhone fingerprint button.

Perhaps the iPhone fingerprint can't be used is caused by disconnection, we need to re-connect the new flex cable. The line inside the flex cable is very thin, total is 19 lines. This can't connect a single cable, we can only remove the flex cable to docking.

Take a new iPhone home button, put it under the Stereo Zoom Microscope, cut off from the position close to the original iPhone home button disconnection, take the end of the socket (try to cut a bit longer), we can separate the lines and lid on the original home button, there is a solder point, directly heated with the QUCIK 861DW hot air rework station, and then pry it with the blade.

After separating the iPhone home button, we can cut off the fingerprint from the disconnection place, scraping fingerprint cable must be very careful, pay attention to the direction cannot be blown back

We've better find some bad home button and then scrap the flex cable to practice, the boot flex cable can also be practiced.

After scraping，apply some tin on it, and then connect the new and old iPhone fingerprint flex cable.

After finish the connection, first we need to test it, if the test is successful, we can reinforce it. Cut off a small piece of discarded fingerprint flex cable, use glue to cover the docking area for protection. After the glue has solidified, install the iPhone and test it again. The iPhone 6 no fingerprint failure repairing done!

Solved: iPhone SE fingerprint not working

The iPhone SE fingerprint failure includes 2 cases, one is the iPhone SE fingerprint function can't be opened, the other one is the iPhone SE fingerprint can be opened smoothly, but the iPhone home button is not responding when adding a new fingerprint, we need to repair iPhone SE fingerprint failure.

1. The iPhone SE fingerprint can't be opened smoothly

Disassemble the iPhone SE by phone opening tools, and then remove the iPhone SE logic board.

Use multimeter to measure the iPhone SE to check whether there are the 1.9V (PP1V9_MESA) and 3.1V (PP3V1_MESA), you can test it by pressing the iPhone power button.

If the 1.9V (PP1V9_MESA) and 3.1V (PP3V1_MESA) doesn't exist, then you can fix it by short connect FL4100 and FL4105.

If both the 1.9V and 3.1V are exist, then use Fluke 15B+ Digital Multimeter to measure the diode data, if the data is infinitely large, check the corresponding circuit, and short connect FL4110, R4111, FL4112, FL4114 and R4116.

If the voltage or diode data is abnormal at the beginning, after repairing, the data back to normal, but the iPhone fingerprint still can't be opened, you can fix it by flashing iPhone or erase all data on iPhone SE.

2. If the iPhone SE fingerprint can be opened smoothly, but the iPhone home button is not responding when adding a new fingerprint.

Measure the diode data for this pin (as shown in picture 1) to check if it has the diode data.

If it has no diode data, then use QUICK 861DW to short connect FL1407.

If it has the diode data, then use Precision Titanium Alloy Tweezers to replace the new U4040, because the damaged fingerprint power supply U4040 can cause iPhone SE adding fingerprint failed.

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.