Today, we need to fix an iPhone 6, which problem is that the iPhone 6 touch function can't used normally. This iPhone 6 has been repaired several times, but all failed. Now, VIP Pro Shop Team will use professional phone repair tools to troubleshooting it.
After we received the iPhone, we tested it
and found that the fault was a little different. The specific failure
performance is that the iPhone shows normal after entering the IOS, touch it
with your fingertips has no effect; Touch it with your finger on the iPhone display screen, it works but not sensitive; If a little
bit of force is used to press the screen to slide, it can be used normally.
However, it's obvious that the owner of iPhone can't use the phone properly.
Testing it by disassemble the iPhone, we
found the white touch IC and black touch IC has been replaced.
Because the phone has been repaired many times, although not repaired, but
these two chips have been replaced, which means that they are normal. And then
we according to the fingers with a little force can slide to judge the line
that from black touch IC to touch socket and
touch socket itself are good. Because if they are abnormal, either the display
screen will appear with a vertical bar or the touch is completely unavailable.
Either lack of transverse or lack of vertical, but in the actual test did not
find a lack of transverse or lack of vertical phenomenon, so the above
judgments is correct.
And then according the above phenomenon, we
judged the circuit line that from iPhone CPU to white touch IC also normal, so we
decided to repair it starting from these two chips peripheral circuits. Use Fluke
15B+ Digital Multimeter to measure the black touch IC +-5.7V
voltage and 1.8V voltage, all is normal. Measuring the white touch IC 5.1V and
1.8V, also is normal. Then we think it would be more precise to use the Hantek DSO1060 oscilloscope to measure, but the result of the
oscilloscope measurement is normal. There is no idea now, we open the WUXINJI
circuit diagram and analyze it, see if we can find out the reason and solution.
After checking the WUXINJI
circuit diagram, seems find nothing. But we see a bias
capacitor C2439 on the black touch circuit, and then think of the iPhone that
was repaired, which the audio have sound, but the sound is small or very light
fault, all of these failures are repaired by replacing the audio bias capacitor
next to the iPhone audio IC. Will this touch faulty be caused by this
bias capacitor?
Measure the diode data of other ungrounded
ends first, we found that it's about the same as the normal board, but we still
decided replace it with new one. Then we remove a same capacitor from damaged
motherboard, and install it with QUICK 861DW soldering station.
Install the iPhone and test it, now the touch function has regained sensitivity. The iPhone owner can use it normally!
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