Today, we're going to share a solution for water-damaged iPhone7 won't turn on problem. The boot current is large, the iPhone screen always black, and so on. Here, you can get a solution for fixing it.
After disassemble the iPhone by JM-9102 Disassemble Tools, we can see the mist in the iPhone, so we
need to handle the mist first. After it is done, measure the iPhone with DC power supply, apply some power on iPhone, and then
press the Power-on button to check the boot current, it shows large current.
According to the current situation, this
phenomenon should be the load of the power supply is short circuit. Now, we
immediately use a method of feeling temperature to check, we found the lower
part of the iPhone was hot. To narrow the scope, we can use the method of
solder rosin to check, we found that one of the reserve
capacitors in the light boost circuit was shorted.
With the help of YH898D
hot air gun and Titanium Alloy Tweezers, we remove this capacitor, and then test
it again, the current returns to normal.
However, the iPhone screen still no lights,
sometimes we can see a little faint light. Using Fluke 15B+ Digital Multimeter to measure the voltage of lighting, it
instantly shows 11V, then immediately turns 2.4V, sometimes turns 5V, and the
voltage is very unstable. At this time, we know there's a problem with the
lighting booster circuit.
Observing the iPhone motherboard under a VGA
Camera 7-45X Trinocular Stereo Microscope, we found a glass-diode crack in the
booster circuit. Direclty replace it with new diode.
May be the user in the iPhone after the water, power on it and
test, because of the continuously working, the diode is burned. And the repairing of mobile phones is
not only a theory, but also a variety of methods, such as Temperature-sensing
method, Solder rosin method, and Microscope observation method, etc.
Finally, install the iPhone 7 and test it, now the iPhone touch screen can be display normally. The repairs end!
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