Slove iPhone 7 No 4G Signal After Water Damage

This article describes how to repair the iphone 7 No 4G Signal after Water Damage.we received an iPhone 7 device, after inserting SIM card in, it only diaplays 2G signal instead of 4G signal.

If there is only 2G signal on the mobile phone, which indicates the 4G signal parts get some problems. This situation only happens after your cell phone taking water in, the water damaged part is in the 4G signal channel.

First of all, use iPhone repair tool kit to open the device, and remove the motherboard to observe under HDMI camera stereo microscope, but we can't see nothing from it, so remove the 4G power amplifier chip.

Remove the TDDPA_RF 4G power amplifier chip and measure the resistance value of the pad with Fluke digital multimeter. We found that the value of 11 pin MLB_PA_VBATT is infinitely large to the ground, it seems that the part is broken. As shown in picture 17-9-2.

picture 17-9-1

Check the circuit diagram on WUXINJI dongle, we found that some voltage go to TDDPA_RF and MLBPA_RF2 chips, the MLBPA_RF chip was not installed.

The voltage is PP_PA_VBATT, which is renamed to MLB_PA_VBATT by R7113_RF resistor. The R7113_RF resistance has been corroded under microscope, as shown in picture 17-9-2.

picture 17-9-2

The circuit icon is recognized as 0 ohm resistor, so we directly short connect.

Now, test the iPhone 7 4G signal again, it return to normal, water damage caused insufficient power supply of 4G power amplifier, resulting in no 4G signal.

More free repair guide follow this link:https://www.vipprogrammer.com//news&zenid=f0v7c43p263ags3ia26hlnmbo0

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