We received an iPhone 6S, which won't turn on after normal use, no dropping, no water damaged, the iPhone appearance is good. After checking, vip pro shop team used 5 steps has fix this problem. Let's look at it.
1. Open the iPhone screen by phone opening tools, there is no traces of water corrosion. Measure the resistance of battery, the data is normal. Use multimeter to test the it, the voltage it directly up to 1.8A, which belongs to the large current
2. Tear
down all the accessories and starting with a single iPhone
6S motherboard, the result is the same, so you can be sure that
the accessories or parts are ok. Before we fixed a lot of large current cell
phone devices, power on and directly measure value, making sound is basically
the components on VCC main power supply get problem, but the situation of
current up to 1.8A is still relatively rare.
3. After determining the measurement,
we can confirm the problem is from VCC circuit, for big current device, you can
use rosin with soldering station,
apply rosin on the solder iron and work on VCC main circuit components, it will
produce white smoke, power on again, you can see Q2300 charging switch tube
quickly shine. The part is shown in picture 10-1-1 .
This
will make people think that the booting problem is caused by this parts,
according to our experience, it's not caused here.
Two
circuit power supply is shown in picture 10-1-2 .
Because
this component focuses on B+ and VCC power supply, so it's heating firstly, but
it can be determined that it's not bad, for 6S 1.8V device, you can directly
focus the problem on backlight part. The backlight part is
easy to burn out.
4. Open
the iPhone CPU shield (setting spiral hot
air gun 260 degrees can easily take off, avoid high temperature, so as to avoid
CPU solder explosion), we find the
traces of components are burn out on the two backlight diode and C4023, it is
best to pack first before processing elements near the CPU. As shown in picture
10-1-3.
5. Disassemble
two diode and a capacitor and power on again is normal, deal with the solder
pad with low temperature solder. you
should be gentle when handling it since the pad is easy to fall off. Replacing
the new components, reboot and test, every function is normal now. As shown in picture 10-1-4 .
Tips:
1. This
iPhone 6S problem is solved after replacing two diodes and capacitor C4023.
Some of the backlight IC and backlight inductance get yellow, which will be
required to be replaced. 6S backlight parts are easy to be broken, and the
components are all covered with glue. When you remove it, don't be impatient.
It will be convenient for the following work after the glue is removed.
2. If the diode is installed in the reverse will appear large current phenomenon, after the replacement, you can test again by solder iron with rosin so that will be more intuitive to see whether it is installed, C4023 capacitor must be installed, otherwise it is easy to burn the iPhone backlight IC.
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