SLOVED: iPhone 6 cannot boot after replace LCD screen

The display screen of iPhone 6 was broken, and then we replace the new screen. However, the iPhone 6 cannot boot. What's going on? Vip Pro Shop Team will help you to solve this problem.

Now, disassemble iPhone and connect it with multimeter for normal standby. Press the power button, the current jumping change is normal and enter into booting state, we can judge the fault is on the display circuit.

In accordance with the customer's words, the fault was caused by damaged screw hole when installing the screen, which results in the display circuit signal disconnection and non display. Then we measure the value on display seat and found that the reset signal is infinite, by the time the screw hole should be repaired with jumper wire . As shown in picture 3-1-1 and 3-1-2.

 

After the jumper wire is repaired, turn on the iPhone 6, it can display normally. When the system function is tested, we found that the touch can not be used. The value of the touch synchronization signal is found to be too large when the value is displayed on multimeter, as shown in picture 3-3-3. The normal sync signal should be about 20 lower than the reset signal, but the secondary level value of this board sync signal is about 10 larger than the reset signal.

With the bitmap synchronization signal,  there is a test point in the vicinity of the screw hole, it shows normal value on the test point, directly connect jumper wire from the test point to display seat.

Now booting the iPhone 6 to test, finally the touch is normal. The display fault is solved!

SOLVED: No response when the iPhone 6S is powered on

 The iPhone 6S accidentally fell to the ground, and then it has no reponse when boot it.  Online state is not normal, drive also displays incorrectly, as shown in picture 1, this phenomenon is usually caused by virtual soler on CPU. This device was fell over by customer, so we can judge that the reason must be the virtual solder. 

After soldering CPU with solder station, the iPhone 6s can be normal online, but it displays error 4013 when flashing system.

The error 4013 is reported when the progress bar just appears on screen, as shown in picture 1.

For iPhone 6S device, if this phenomenon happens, which are generally baseband problems, so we remove the baseband, indeed some tin points come off. 

Make jump wire on the disconnected but useful pin, install chip on it, but it still shows error 4013 when flashing, seems there is still a problem exist. Rooting the device repeatedly, we find when white apple appears, baseband S3, S4, S5 voltage can be instantly measured with power supply besides S2, but we still can measure the ground value on S2, is it the baseband power failure? Remove the baseband power supply chip, by the way of measuring its pin, it is found that the 91 and 97 pin of the baseband power supply IC are blocked. so we can see the problem has been found here. Remove the inductance, its pin has been damagd. The front is good while the reverse falls a pin. 

So we replace the damaged parts and install original fingerprint, the progress bar is normal when flashing now. The repairs ended here!

Troubleshoot: Apple iPhone 6 Plus touch function failure

We got a iPhone 6 Plus with problem, the owner of iPhone 6 Plus said that the touch of iPhone

is malfunctioning.  It has been repaired in local repair shop, but after a few days of use, the issues came back.  It was repaired several times, but it didn't work.  Vip Pro Shop Team speculated that the U2402 black touch IC was damaged.

After check the iPhone 6 Plus, the device was dropped on ground accidentally by customer, the touch failure fault is definitely caused by U2402 black touch IC M1 pin sync signal disconnection. It has been repaired, but there will still be the same phenomenon for touch failure, as if the fault was expanded after the last repairs. Remove the U2402, and reinstall the jumper, the iPhone 6 plus device can be used for a while, but there will be no touch function phenomenon, it seems that the problem is not from here. After careful observation under microscope, it shows that the inductance and capacitance of J2019 diplay pin get tin explosure. As shown in figure 7-2-1.

Measure the ground resistance, as shown in picture 7-2-2 and 7-2-3, the inductance of signal synchronous is virtual soldered.

So we solder it back with a soldering iron, resistance shows normal now. As shown in picture 7-2-4.

Install the iPhone 6 plus and test again, a day later appeared the display fault again.  Measure the resistance of display pin, we find there are no resistance in many parts, gently touch inductor and capacitor with tweezers under the microscope, all of them can be moved, it looks like a large scale is virtual soldered. So we decisively disassemble the whole parts and re welding them again. As shown in picture 7-2-5 and 7-2-6.

Intall the device and test, everything is normal now,the backside seal  inductor and capacitor is virtual soldered, which may be caused by long-time air gun blowing operation. The whole maintenance process is finally successful!

Repair iPhone 6 cannot turn on after charging

Last night,  the iPhone 6 is charging.  Today, i want to use it,  but i found it cannot turn on.  After we check it,  the power supply was short circuit (power supply grounding)

Power supply short circuit is mostly from two groups of power supply problems: battery power supply(PP_BATT_VCC), charging tube output power supply (PP_VCC_MAIN). If there is one of the power supply grounding between them, the short circuit fault as the iPhone 6 will be caused.

First of all, we need to judge which group power supply causes the problem, measuring the battery power supply (PP_BATT_VCC) to check whether the battery interface is connected with positive and negative port, if not, it means the first group of power supply has no problem, on the contrary, it would be the first group power supply problem. The two groups power supply circuit picture are shown in picture 4-10-1.

After measuring the iPhone 6 device, we get to know the fault is the charging pipe output power supply (PP_VCC_MAIN). First, we offer artificial power supply in the second group power channel to see if the component is hot, but there is no element heating phenomenon. By checking on the schematic diagram, there are dozens of places through, so we need to dismantle the components one by one. Take off the charging tube U1401 and electronic switch Q1403 on the motherboard as shown in picture 4-10-2, the fault still exist.

Now we can only measure the internal resistance of components on the channel by milliohmmeter to see if there are any difference, after one by one measurement, we found that on the upper right corner of the main CPU, the C1552 internal resistance is 37 mOhm, the value is small.

The second group charging tube output power supply (PP-VCC-MAIN) channel diagram, as shown in 4-10-3.

Finally, remove C1552 by a soldering iron, the problem is solved.

Note: the C1597 next to C1552 is also easy to get a short circuit.