A minor flash issue in an iPhone 12 turned into a major headache for a repair technician. Improper repair practices led to the failure of Wi-Fi and Baseband functions, making the repair far more complicated. This guide will take you through the troubleshooting and repair process for resolving these issues while emphasizing the importance of clean and precise repair habits.
Defect Phenomenon
After the drop damage, the flash function stopped working. So the phone owner sent it to a repair shop.
Initial Diagnosis: The repair technician suspected a motherboard problem.
Actions Taken:
- Changed flash flex cable to test but the issue remained.
- The technician desoldered and separated the two layers of the motherboard for further testing.
- Upon separation, it was discovered that both the Baseband and Wi-Fi functions had failed.
Outcome: The initial issue remained unresolved, and additional problems with the Baseband and Wi-Fi functions were identified after the motherboard separation.
Troubleshooting
Analyze the Motherboard
- Received the phone with the motherboard already separated.
- Suspected poor connection between the two motherboard layers.
Recombine the Motherboard Layers
- Align the two layers on a heating platform.
- Heat at the proper temperature to securely recombine the layers.
- Result: Flash function restored, but Wi-Fi and Baseband functions are still abnormal.
Examine the Motherboard
- Separate the motherboard again for detailed inspection.
- Focus on the signal board since it controls Wi-Fi and Baseband functions.
- Observation: Tin balls on the bottom side caused bridge connections.
Repair Process
Remove Affected Chips
- Desolder the chips at the bottom part of the motherboard one by one.
Clean the Tin Pads
- Thoroughly clean the tin pads using appropriate tools to remove excess tin balls.
Reassemble and Solder Chips
- Solder the cleaned chips back onto the motherboard.
Test Functionality
- Use a test fixture to confirm that Wi-Fi and Baseband functions are restored.
- Dial *#06# to verify device information and check the Wi-Fi button.
Final Outcome
- Flash: Function restored after recombining the motherboard layers.
- Wi-Fi & Baseband: Fixed by cleaning and resoldering the chips on the signal board.
Lessons Learned
- Precision is Key: Avoid contaminating the motherboard with tin balls, excess flux, or paste during repairs.
- Proper Diagnosis: Always test systematically before separating the motherboard to prevent unnecessary complications.
- Repair Cleanliness: Maintain clean and organized work habits to minimize risks and ensure successful repairs.
Conclusion
Even a small repair issue, like a faulty flash, can escalate if improper techniques are used. This case demonstrates the importance of following clean and precise repair processes to avoid additional problems like Wi-Fi and Baseband failures. Always approach repairs with care, and learn advanced techniques to handle complex issues effectively.
For more repair tips and tutorials, visit REWA Academy.
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