Short circuit error: iPhone 6 no display after dropping

It’s unfortunate that your iPhone fell, because most of the time, it means your iPhone is going to break down. In this case, the iPhone 6 fell to ground,  and then when we boot it, the screen shows nothing. This is so sad. But, don’t complain all we need to to is find the way to fix it.

First, disassemble the iPhone and energize the motherboard. The DC power supply displays 1.7V current that is short circuit and the adjustable power supply voltage is pulled down to 3.4V. The whole motherboard gets hot, especially the main power drive chip .

Second, deenergize it and measure the power supply of each circuit at motherboard through digital multimeter, find that the power supply of PP3V0_NAND of EEPROM is short circuit to ground and the resistance data is 0. The test points of PP3V0_NAND are shown in picture 1-1.

Example93-2

Third, use solder iron to make rosin in the capacitance which connect PP3V0-NAND, then slowly turn the current button of adjustable DC power supply to increase the current limit, the inductor that is connected with PP3V0_NAND melts when the current is 3A. Therefore, this inductor is short circuit. Deenergize it and remove this inductor, as shown in picture 1-2.

Example93-4

Fourth, after removing this inductor and plugging adjustable power supply, it is not short circuit. IPhone can get into IOS normally. Remove a inductor from the same place of the accessories pad to replace the old one. This problem was been solved.

Tips:

As this 3V voltage is parallelly connected many capacitors. It will take long to tear them one by one. Thus we use burn-in method to find the short circuit point. Put rosin on motherboard and set the adjustable power supply to 3V. Adjust the current limit to the lowest. Connect the negative pole of adjustable power supply to ground and connect the positive pole to the short circuit point. Then energize it. Slowly turn the current button of adjustable DC power supply to increase the current limit. The place that rosin melts fastest is faulty.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Blog at WordPress.com.

Up ↑

%d bloggers like this: