How to fix iPhone 6 can't boot and no backlight
Have you ever encountered an iPhone that cannot be turned on and has no backlight failure? This is a very desperate thing. How to fix it? We received an iPhone 6 from the customer. The fault is that the iPhone 6 cannot be turned on. The iPhone motherboard has been dug up and soldered with jumpers. as the picture shows.
First connect the iPhone motherboard to the DPS DC power supply to check the current situation. We found that the iPhone's current is higher than 200mA, then it drops and stays at around 150mA. According to the iPhone to start the current workflow, the iPhone has not yet started. Use a digital multimeter to measure the ground resistance of the display and backlight circuit.
The resistance value measured is normal, so we replace the iPhone display IC, but the problem still the same after replacement. Now, we need to replace the iPhone backlight IC, after replacement, we found the iPhone boot current jumps normally. Install the iPhone display assembly and test it, the iPhone can be turned on, and the backlight also is normal. However, when the iPhone came to unlock the interface, the iPhone display screen suddenly became dark and then completely black, the iPhone backlight didn't work anymore, and the iPhone boot current stays at the same value as before.
Seems it's the iPhone backlight problem, and it causes iPhone can't enter the IOS smoothly. Replace the several iPhone backlight ICs, but it is still not working. Measuring the voltage with digital multimeter, the working condition of the iPhone backlight all is normal, only the voltage of backlight boost 17V are not up to the normal value. Check iPhone by the light, we can see that the iPhone screen stuck in the boot interface.
Replacing the iPhone backlight IC is useless, so we are going to replace the iPhone backlight IC, iPhone diode tube and inductors.
After replacement, the iPhone was normal at first, but it didn't work the second time it turned on. Check iPhone schematic diagram via WUXINJI Dongle, we found there are many wires under the screw column, which includes the wire of the iPhone backlight circuit.
Put iPhone under the Stereo Zoom Microscope, dig the iPhone motherboard，we found the cathode wire of iPhone backlight is cracked, solder the jumper wire on it, and then apply some green UV oil.
Connect iPhone motherboard to DC power supply to test it, the problem still the same, so it's not the problem of the board layer circuit line. Ask another colleague, he said there were another situation that would cause the iPhone no backlight, which is DWI bus from the CPU to the backlight IC and the main power supply, it is used to adjust the brightness of the backlight. We can remove the iPhone backlight and main power, and then measure the grounding value of the DWI bus, if all is normal, then need to replace the iPhone main power IC.
After measuring the data of the DWI bus, the test data is normal. Finally, we replaced the iPhone power IC and then reinstalled the iPhone backlight IC. Open the iPhone and test it. Now that the iPhone backlight is working properly, the iPhone can be opened smoothly and can enter the IOS system normally.
Do you interested in this article? If you have question about phone repair tools, please contact us at www.vipprogrammer.com.
First connect the iPhone motherboard to the DPS DC power supply to check the current situation. We found that the iPhone's current is higher than 200mA, then it drops and stays at around 150mA. According to the iPhone to start the current workflow, the iPhone has not yet started. Use a digital multimeter to measure the ground resistance of the display and backlight circuit.
The resistance value measured is normal, so we replace the iPhone display IC, but the problem still the same after replacement. Now, we need to replace the iPhone backlight IC, after replacement, we found the iPhone boot current jumps normally. Install the iPhone display assembly and test it, the iPhone can be turned on, and the backlight also is normal. However, when the iPhone came to unlock the interface, the iPhone display screen suddenly became dark and then completely black, the iPhone backlight didn't work anymore, and the iPhone boot current stays at the same value as before.
Seems it's the iPhone backlight problem, and it causes iPhone can't enter the IOS smoothly. Replace the several iPhone backlight ICs, but it is still not working. Measuring the voltage with digital multimeter, the working condition of the iPhone backlight all is normal, only the voltage of backlight boost 17V are not up to the normal value. Check iPhone by the light, we can see that the iPhone screen stuck in the boot interface.
Replacing the iPhone backlight IC is useless, so we are going to replace the iPhone backlight IC, iPhone diode tube and inductors.
After replacement, the iPhone was normal at first, but it didn't work the second time it turned on. Check iPhone schematic diagram via WUXINJI Dongle, we found there are many wires under the screw column, which includes the wire of the iPhone backlight circuit.
Put iPhone under the Stereo Zoom Microscope, dig the iPhone motherboard，we found the cathode wire of iPhone backlight is cracked, solder the jumper wire on it, and then apply some green UV oil.
Connect iPhone motherboard to DC power supply to test it, the problem still the same, so it's not the problem of the board layer circuit line. Ask another colleague, he said there were another situation that would cause the iPhone no backlight, which is DWI bus from the CPU to the backlight IC and the main power supply, it is used to adjust the brightness of the backlight. We can remove the iPhone backlight and main power, and then measure the grounding value of the DWI bus, if all is normal, then need to replace the iPhone main power IC.
After measuring the data of the DWI bus, the test data is normal. Finally, we replaced the iPhone power IC and then reinstalled the iPhone backlight IC. Open the iPhone and test it. Now that the iPhone backlight is working properly, the iPhone can be opened smoothly and can enter the IOS system normally.
Do you interested in this article? If you have question about phone repair tools, please contact us at www.vipprogrammer.com.
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