Fast Fix iPhone 6 Charging Failure @ diyphonetool的部落格

According to the attached file, we know there exist a unresponsive when plug in charger and we also have checked the charging interface, no anything shows in it.

We direct test the battery seat voltage B+ with Fluke 15B+ Digital Multimeter, it displays 0.46V, there is no voltage can directly exlcude the battery problem. Test battery resistance B+385 which shows normal, disassemble the single board. There exist a test point below the battery interface, if the value shows 5V, it means there no problem with the tail plug. So we have to continue the testing.

Measure whether the capacitance C1704, C1408 has 5V voltage, if neither of them has 5V voltage, you can short connect Q1701' s pin 1 and pin 3. If either of the two capacitance has 5V voltage, then jumper wire can help to solve. At the same time, Q1701 may cause the phenomenon: turn off the iPhone 6 can be charged while boot can not be charged. the same method short connection can be applied for solving this problem.

Open and check WUXINJI schematic diagram, If both 5V power supply are normal, then test the 4.2V on the battery seat and test the C1417 and C1412. If either of them has no 4.2V, you can short connect Q1403; If both of them have no normal voltage, then you can replace the U2 (U1700) or the U1401 charge tube. U1401 charging tube damage usually has charging icon, and the more electric charge is, the less charge will increase, it won't increase anymore when approaching the certain electric charge.

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U2 has a large failure rate in iPhone repair(single board boot 250mA, with DC power supply, it will auto jump about 200mA, battery power display is inaccurate, battery power consumption fast, unable to identify USB, non computer and so on).

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For iPhone 6, NAND is on the top of U2, and there is baseband power below U2. There is a baseband CPU on the back of it. Before disassembly, you can use heat resistant tape to protect the ICs from high temperature and cause other problems. Charging fault detection method for iPhone is basically universal (U2 chip A3B model is common used for iPhone 7).