If your iPhone shows “No Service” in the status bar (even if baseband is available), it can caused by either software or hardware issues. We have received an iPhone 7 from our customer claimed it has “No Service” problem, In this article, we will share how to troubleshoot and fix iPhone 7 no signal/no service through chip-level repair, hope you enjoy our sharing.
Step 1 Function Test
Insert the SIM card, power on the iPhone and turn off the Airplane Mode, the iPhone shows No Service. Open Settings＞General＞About, both baseband (Modem Firmware) and ICCID has data, proving the iPhone can read the SIM card.
Step 2 Diagnosis
Measure the diode resistance of the RF circuit power supply and discover the diode resistance of C7117_RF is measured short circut. As the power amplifier IC QPOET_RF provides power for signal amplifier and the power goes through C7117_RF, therefore the C7117_RF short circuit will cause no signal.
Step 3 Troubleshooting
Remove the power amplifier IC QPOET_RF and remeasure the diode resistance, the diode resistance remains short circuit. Remove the low-frequency amplifier IC and remeasure, the diode reisstance showed normal. Therefore, it’s the defect low-frequency amplifier IC that caused the short circuit
Step 4 Repairing
Replace a new good low-frequency amplifier IC and remeasure the diode resistance of C7117_RF. The diode resistance showed normal.
Step 5 Reassemble & Test
Reassemble the motherboard then power on the iPhone, signal backs normal, repair completed.
Please refer to below detailed video:
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Tools and Materials Used in This Video:
Hot air gun
Desoldering braid/ solder wick