iPhone 6 Plus touch screen not working- how to fix?

The iPhone 6 Plus touch is not working, becuase it doesn't response to the touch, how to fix it? 

First, we try to fix it by replacing iPhone touch screen. Use phone open tools to disassemble the iPhone, remove the iPhone display assembly, and then install the new iPhone display assembly. After replacement, power on iPhone and test the iPhone touch screen, it's still not working.

Now, we need to check iPhone motherboard. The bottom of the UMT board is easy to disconnect, first we need to handle the iPhone touch error. There are 2 ways to remove the IC: one is remove it by tweezers; the other one is pry it from the side the IC.

Remove the iPhone touch IC and the re-install it, the iPhone 6 Plus auto restarts when the white Apple appears. Measure the iPhone by DC power supply, the boot current jumps from 300mA.

Take off the iPhone touch IC again to measure the resistance of the bottom of the board by digital multimeter, the resistance value measured is normal.

We didn't meet this problem before, what's the real problem? Because the boot current is larger than normal value, so we are going to measure the boot current after removing the U2 IC, but the problem still there. Measure the resistance value of the bottom pin of the iPhone U2 IC, we found the F4 pin PP3.0V is short circuit.

After check iPhone schematic diagram via WUXINJI Dongle, we know that this circuit has big power, fingerprint power supply and U5411_RF.

Supply power to the iPhone to boot it again, we found the U5411_RF is overheating, remove the 2 components that next to the U2, the iPhone is turned on, we confirmed that this iPhone problem is caused by damaged U5411.

The iPhone boot current jumps from 300mA, the iPhone displays white Apple and won't enter the iOS system. Installing the iPhone touch IC, the new faults comes out after testing, the iPhone has no service and no IMEI after booting.

For this drop-damaged UMT motherboard baseband failure, remove the iPhone baseband CPU, and use QUICK 861DW hot air rework station to solder the jumper wire to V1 and U1.

After soldering the jumper wire, solidified it by painting green UV oil, and then reballing the tin on the iPhone baseband CPU.

Now, install the iPhone, press the iPhone power button, after entering the IOS, touch the iPhone touch screen, now it reponses smoothly.

Repair Guide: iPhone X won’t turn on after dropping(error 56)

 The iPhone X won't turn on and reports unknown error 56, why is that? The iPhone 6 accidentally fell into the ground, and then it can be turned on as usual, according to our repair experience, we think it's the problem of the iPhone motherboard. 

Conect iPhone X to the computer by iPhone lightning cable, and then use iTunes to re-flash it, the iPhone is failed to flash, the iTunes reports unknown error 56.

Disassemble the iPhone X by phone opening tools, take out the iPhone X motherboard. With the help of the PPD 120XL iPhone X pre-heating platform,we can separate the iPhone X motherboard smoothly. 

As we know,    the iPhone X is connected by 2 pieces motherboard via a middle column, so the pins are easy to lose because of dropping. Now, it's possibly the pin from the NFC chip to the iPhone CPU that was dropped off.

Check iPhone schematic diagram via WUXINJI Dongle, it's surrounded by ground lines, and the 6 useful pins was dropped off.

The ground lines are no need to fill, we just need to fill these 6 useful pins, we can check iPhone motherboard under the Stereo Zoom Microscope. These all are the signal line of the NFC chip, so when we restore iPhone by iTunes, it reports unknown error 56.

Next we need to plant the tin in the middle column by QUICK 861DW hot air rework station, and then re-weld the AP part.

After installation, assemble the iPhone, and then re-flash it agian, now the flash process goes well. 

After entering the IOS system, test the function on iPhone X, all functions tested are normal.

Step By Step to fix iPhone 7P front camera failure

 Last week, we received an iPhone 7 Plus to repair, the problem is that this iPhone 7P front camera is not working, it won't take photos, just shows black. We fixed it step by step, here is the repair process.

Step 1

Get into IOS system and test the iPhone camera. The iPhone rear camera, flash and other functions are all normal, but the iPhone front camera is not working.

Step 2

Use phone opening tools to disassemble the iPhone, and then remove the iPhone motherboard.

Step 3

Put iPhone motherboard under the Stereo Zoom Microscope to observe,  we found the repair traces of front camera J4503 base. It means the iPhone 7 Plus was repaired before. As shown in picture 1.

Step 3 

Measure the iPhone motherboard by digital multimeter, the data tested is normal.  When measure the voltage of the 2 groups of I2C that were repaired: (R4810) I2C_NH_SCL_CONN and (4811) I2C_NH_SDA_CONN, we found R4811 resistance has no voltage, but it has value when trigger. The circuit diagram we can check on WUXINJI dongle.

Step 4

Now we can judge that R4811 is damaged, so we need to replace it. With the help of the QUICK 861DW and tweezers, we remove the incoming panel and replace the two pull-up resistors.

Step 5

 

Assemble the iPhone 7 Plus, power on iPhone 7P, and then test it, the iPhone front camera works perfectly.

iPhone 6 failed to boot and no backlight—Fixed details!

The iPhone 6 is very old version, and it's reasonable to have some problems. Here is an iPhone 6 with not turning on problem and no backlight. Luckily, we can fix it, and here is the fixed details. 

Use phone opening tools to disassemble the iPhone, and take out the iPhone motherboard to the oberve it,  we found that the top right corner screw column of the iPhone CPU is missing, the iPhone motherboard has been dug and welded jumper wire.

  

Connect iPhone motherboard to the DPS DC power supply to check the current condition, we found that the iPhone current was above 200mA, then dropped and stayed around 150mA. According to the iPhone boot current working process, we analyze that the iPhone isn't turned on when the current was above 200mA, this failure is usually caused by iPhone display and backlight circuit. Use digital multimeter to measure the grounding resistance value of the display and backlight circuit.

The resistance value measured is normal, so we replace the iPhone display IC, but the problem still the same after replacement. Now, we need to replace the iPhone backlight IC, after replacement, we found the iPhone boot current jumps normally. Install the iPhone display assembly and test it, the iPhone can be turned on, and the backlight also is normal. However, when the iPhone came to unlock the interface, the iPhone display screen suddenly became dark and then completely black, the iPhone backlight didn't work anymore, and the iPhone boot current stays at the same value as before.

Seems it's the iPhone backlight problem, and it causes iPhone can't enter the IOS smoothly. Replace the several iPhone backlight ICs, but it is still not working. Measuring the voltage with digital multimeter, the working condition of the iPhone backlight all is normal, only the voltage of backlight boost 17V are not up to the normal value. Check iPhone by the light, we can see that the iPhone screen stuck in the boot interface.

Replacing the iPhone backlight IC is useless, so we are going to replace the iPhone backlight IC, iPhone diode tube and inductors.

After replacement, the iPhone was normal at first, but it didn't work the second time it turned on. Check iPhone schematic diagram via WUXINJI Dongle, we found there are many wires under the screw column, which includes the wire of the iPhone backlight circuit.

Put iPhone under the Stereo Zoom Microscope, dig the iPhone motherboard，we found the cathode wire of iPhone backlight is cracked, solder the jumper wire on it, and then apply some green UV oil.

Connect iPhone motherboard to DC power supply to test it, now the data tested is normal. 

Insall the iPhone motherboard, connect iPhone battery and iPhone display assembly, and then press the iPhone power button, the white Apple logo appears as usual, after few seconds, the iPhone is enter the IOS systems smoothly. 

Using it for 1 day, the iPhone 6 is working properly, and all functions tested are normal.