iPad Air displays white Apple logo and then reboots repeatedly
When you use the iPad have you ever been in this situation: The touch screen of your iPad suddenly displays white apple, and reboots repeatedly. What do you need, and how do you fix. we all share a common target, which is to get your phone back to work again. This guide from vipprogrammer.com will offer you some practical instructions on how to deal with iPad Air displays white Apple logo and then reboots repeatedly caused by software faults, hoping you will benefit from it.
Trouble Phenomenon：
The iPad shows white Apple logo after power on and then shows black screen, later white Apple logo again. It reboots repeatedly, as shown in below picture.
Repair Process：
1. After teardown, remove shielding case and press the power button. When iPad shows white Apple logo, use hand to touch each main chip and feel power chip U8100 hot. Without connecting display screen, press power button. Touch U8100 and now it is not hot.
2. Analyze according to display circuit working principle. Without display screen, the backlight bootstrap circuit of display screen does not work. With display screen, the circuit will work. Thus, the problem happens on the display screen backlight bootstrap circuit.
3. Continue to analyze the backlight bootstrap circuit (in below picture). IPad Air’s backlight bootstrap circuit has two voltages, PPLED_OUT_A and PPLED_OUT_B.
4. After measuring, the voltage drop of D8228 on motherboard is 1.9v, which is close to the state of an open circuit. While the normal voltage drop should be about 0.2v. The relevant circuit of D8228 is shown in picture 2-30. Measure the negative pole voltage of D8228 is 0.5v when getting electricity on but do not press the power button. But the normal data should be battery power supply voltage (3.7-4.2v).
5. Based on the data gained above, we know D8228 is damaged. The location of D8228 is shown in below picture. After replacing it and measuring, the voltage of negative pole rises to 16.7v and the chip is not hot. But when enter system, iPad Air still reboots. First root it to exclude the problems from software.
6. Under the stare of power off, press HOME button and then insert USB cable to enter recovery mode to root, as shown in below picture.
7. After using iTunes to install the newest firmware, machine enters system normally, as shown in below picture. Trouble is removed.
There are hundreds of ipad repair tools in the market. But what you should do is to get only those which you need, above is an absolutely indispensable kit for anyone who wants to repair smart phones, ipads and tablets. Lastly, may you have a pleasant experience in your ipad repairing!
Trouble Phenomenon：
The iPad shows white Apple logo after power on and then shows black screen, later white Apple logo again. It reboots repeatedly, as shown in below picture.
Repair Process：
1. After teardown, remove shielding case and press the power button. When iPad shows white Apple logo, use hand to touch each main chip and feel power chip U8100 hot. Without connecting display screen, press power button. Touch U8100 and now it is not hot.
2. Analyze according to display circuit working principle. Without display screen, the backlight bootstrap circuit of display screen does not work. With display screen, the circuit will work. Thus, the problem happens on the display screen backlight bootstrap circuit.
3. Continue to analyze the backlight bootstrap circuit (in below picture). IPad Air’s backlight bootstrap circuit has two voltages, PPLED_OUT_A and PPLED_OUT_B.
4. After measuring, the voltage drop of D8228 on motherboard is 1.9v, which is close to the state of an open circuit. While the normal voltage drop should be about 0.2v. The relevant circuit of D8228 is shown in picture 2-30. Measure the negative pole voltage of D8228 is 0.5v when getting electricity on but do not press the power button. But the normal data should be battery power supply voltage (3.7-4.2v).
5. Based on the data gained above, we know D8228 is damaged. The location of D8228 is shown in below picture. After replacing it and measuring, the voltage of negative pole rises to 16.7v and the chip is not hot. But when enter system, iPad Air still reboots. First root it to exclude the problems from software.
6. Under the stare of power off, press HOME button and then insert USB cable to enter recovery mode to root, as shown in below picture.
7. After using iTunes to install the newest firmware, machine enters system normally, as shown in below picture. Trouble is removed.
There are hundreds of ipad repair tools in the market. But what you should do is to get only those which you need, above is an absolutely indispensable kit for anyone who wants to repair smart phones, ipads and tablets. Lastly, may you have a pleasant experience in your ipad repairing!
评论
发表评论