Micro Soldering iPhone Repair Lecture Notes

Introduction

• Welcome message and introduction by Edgar, micro soldering technician with 15 years of experience.
• Prior experience teaching and traveling for repair classes.
• Focus of the video: steps to take when receiving an iPhone with no power.

Previous Video Recap

• Mention of prior video discussing principal lines in iPhones (iPhone 7 and up).
• Three principal lines discussed:
  • Battery Line
  • BDD Main
  • BDD Boost
• Voltage should be between 250-350 millivolts in dial mode and match the power supply voltage (e.g., ~4V).

Key Components and Functions

• FPC Battery Connector:
  • Connection to main circuit (Tigris) and mosfet (not present in iPhone X and up).
• PMU (Power Management Unit):
  • Powers secondary lines (box and LDOs).
  • Only operates when the power button is pressed.

Important Measurements to Take

1. Power Key Voltage:
   • Should measure 1.8V at the power connector.
2. Oscillator Frequency:
   • Should measure 32 kHz.

Demonstration with iPhone 11 Pro and 12 Pro

• Checking power button on both models.
• Explanation of voltage measurements:
  • Acceptable range: 1.2V to 1.8V.
  • Voltage higher than 1.8V indicates a bad PMU.
  • Voltage lower than 1.2V indicates potential issues.
• Techniques for checking voltage without pressing the power button.

Oscillator Check

• Visual inspection of the oscillator to identify any damage.
• Checking voltage using a multimeter.
  • Acceptable range: typically should measure around 600-700 millivolts.
• Using an oscilloscope for precise frequency measurement.
  • Confirmed measurement of 32 kHz indicates a good oscillator.

First Stage Summary

• Key points to check for the first stage of iPhone power:
  • Principal lines (BDD Main and Boost).
  • Power Key voltage (1.8V).
  • Oscillator frequency (32 kHz).

Next Steps

• After confirming the first stage, the next video will cover what to do when pressing the power button.
• Discussion about boot loop scenarios and troubleshooting further.

Conclusion

• Encouragement to share the video and leave comments.
• Reminder to ask questions if anything is unclear, as Edgar is striving to improve his English explanations.