How to fix iPhone 7 Can’t Find Wi-Fi Network | Chip Level Repair

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We have received an iPhone 7 from our customer who claimed the iPhone has been dropped on the ground, and it has been receiving less network signals, the Wi-Fi connection kept automatically disconnecting as well. Dropping an iPhone can cause motherboard line damage, components defect and chip IC failure, which can affect Wi-Fi. In this article, we will share how to troubleshoot and fix iPhone 7 Wi-Fi signal receiving problem with chip level repair. Hope you enjoy our sharing.

Step 1 Function Test

Since the iPhone has been dropped on the ground and appeared with signal receiving problems, we start with checking whether there is Wi-Fi components damage on the motherboard surface. And there’s no conscious damage or water corrosion under inspection

Step 2 Diagnosis

Turn off and dissemble the iPhone. Measure diode resistance of the LCD connector J4502 backlight circuit pin 35, pin 37, and pin 39. We discovered the pin 39 showed open circuit. Based on schematic diagram, the reasons that can cause pin 39 open circuit are: backlight filter FL3903 open circuit or backlight IC U3701 failure.

Step 3 Troubleshooting & Repairing

Since there’s no conscious damage on the motherboard surface, the reason that caused iPhone Wi-Fi network signal receiving problem is short or open circuit line. There are 3 lines affect the Wi-Fi signal receiving, the JLAT3_RF, the SUAT1_RF and the SUAT2_RF. We start with troubleshooting SUAT1_RF and see whether there’s open or short circuit in this line.

The R6715_RF is measured open circuit, so we need to replace the R6715_RF. Remeasure the R6715_RF after replacement, the diode resistance showed normal

Step 4 Reassemble & Test

Reassemble and power on the iPhone, Wi-Fi network signal receiving strength recovered, repair completed.

Please refer to below detailed video:

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Tools and Materials Used in This Video:

Solder flux

Hot air gun

Tweezers

Solder paste

Soldering net

Microscope

Soldering iron

PCB cleaner

Desoldering braid/solder wick

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