Have you ever met the same phenomenon on your iPhone 6 Plus screen? A customer sent his iPhone, the problem is that the white Apple logo stuck on screen, and it's unable to enter into home page. How to repair the common problem? Let's fix it step by step in this article!
Connect iPhone 6 Plus on DPS Digital DC Power Supply to measure the booting current is jumping from 200mA to 1A, then it becomes a fixed current 300mA, based on our previous repair experience, we estimate it is mostly caused by USB, so we need to firstly check whether it can be online in recovery mode, so we connect the iPhone 6 Plus on computer and check by Ace assistant, the iPhone 6 Plus is not online.
Opening the iPhone 6 Plus and remove the USB chip from motherboard, measure the booting current again, it is still jumping from 200mA, so we can judge it's not USB chip problem, it should be the problem of USB power supply.
Measure the power supply grounding valure around USB by Fluke 15B+ digital multimeter, we found the PP3V0_TRISTAR/PAC_VDD_3V0 is short circuited to the ground. By checking the iPhone 6 Plus bitmap on WUXINJI Dongle, we get to know the power supply is sent from main power supply and through USB, fingerprint boost chip and U5411_RF. It's unlikely to get power failure, so we tear down the fingerprint boost chip, the same fault is not solved.
So we move into the next solution: remove the U5411_RF, since PP3V0_TRISTAR/PAC_VDD_3V0 is powered by L5408_RF to U5411_RF, in order to measure whether it's caused by the U5411_RF, we have to first remove the L5408_RF, measure the booting current again, the starting current valure is normal now, reinstall the USB back.
The fault is found now, what we need to do is to replace a new U5411_RF part by QUICK TR1300A hot air rework station and precision tweezers.
Assemble the L5408_RF and fingerprint boost chip. Install the cell phone to test, all functions are normal now!
If you need any other cell phone repair technical support, please contact us on www.vipfixphone.com
Connect iPhone 6 Plus on DPS Digital DC Power Supply to measure the booting current is jumping from 200mA to 1A, then it becomes a fixed current 300mA, based on our previous repair experience, we estimate it is mostly caused by USB, so we need to firstly check whether it can be online in recovery mode, so we connect the iPhone 6 Plus on computer and check by Ace assistant, the iPhone 6 Plus is not online.
Opening the iPhone 6 Plus and remove the USB chip from motherboard, measure the booting current again, it is still jumping from 200mA, so we can judge it's not USB chip problem, it should be the problem of USB power supply.
Measure the power supply grounding valure around USB by Fluke 15B+ digital multimeter, we found the PP3V0_TRISTAR/PAC_VDD_3V0 is short circuited to the ground. By checking the iPhone 6 Plus bitmap on WUXINJI Dongle, we get to know the power supply is sent from main power supply and through USB, fingerprint boost chip and U5411_RF. It's unlikely to get power failure, so we tear down the fingerprint boost chip, the same fault is not solved.
So we move into the next solution: remove the U5411_RF, since PP3V0_TRISTAR/PAC_VDD_3V0 is powered by L5408_RF to U5411_RF, in order to measure whether it's caused by the U5411_RF, we have to first remove the L5408_RF, measure the booting current again, the starting current valure is normal now, reinstall the USB back.
The fault is found now, what we need to do is to replace a new U5411_RF part by QUICK TR1300A hot air rework station and precision tweezers.
Assemble the L5408_RF and fingerprint boost chip. Install the cell phone to test, all functions are normal now!
If you need any other cell phone repair technical support, please contact us on www.vipfixphone.com
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