Before fixing iPhone 6s boot failure, you have to check if the iPhone device is broken or deformed. Open the iPhone screen to check the traces of water corrosion, the battery resistance is checked with normal value, then test the device with multimeter( 2A am multimeter is recommended ) directly up voltage to 1.8A, it belongs to the high current system.
Tear down all the accessories and starting with a single iPhone 6S motherboard, the result is the same, so you can be sure that the accessories or parts are ok. Before we fixed a lot of large current cell phone devices, power on and directly measure value, making sound is basically the components on VCC main power supply get problem, but the situation of current up to 1.8A is still relatively rare. After determining the measurement, we can confirm the problem is from VCC circuit, for big current device, you can use rosin with electric solder iron, apply rosin on the solder iron and work on VCC main circuit components, it will produce white smoke, power on again, you can see Q2300 charging switch tube quickly shine. The part is shown in picture 10-1-1.
This will make people think that the booting problem is caused by this parts, according to our experience, it's not caused here.
Two circuit power supply is shown in picture 1-1-2.
Because this component focuses on B+ and VCC power supply, so it's heating firstly, but it can be determined that it's not bad, for 6S 1.8V device, you can directly focus the problem on backlight part. As shown in picture 10-1-3, the backlight part is easy to burn out.
Open the iPhone CPU shield (setting spiral hot air gun 260 degrees can easily take off, avoid high temperature, so as to avoid CPU solder explosion), we find the traces of components are burn out on the two backlight diode and C4023, it is best to pack first before processing elements near the CPU. As shown in picture 1-1-4.
Disassemble two diode and a capacitor and power on again is normal, deal with the solder pad with high low temperature solder. you should be gentle when handling it since the pad is easy to fall off. Replacing the new components, reboot and test, every function is normal now. As shown in picture 1-1-5.
Note: If the diode is installed in the reverse will appear large current phenomenon, after the replacement, you can test again by solder iron with rosin so that will be more intuitive to see whether it is installed, C4023 capacitor must be installed, otherwise it is easy to burn the iPhone backlight IC.
This iPhone 6S problem is solved after replacing two diodes and capacitor C4023. Some of the backlight IC and backlight inductance get yellow, which will be required to be replaced. 6S backlight parts are easy to be broken, and the components are all covered with glue. When you remove it, don't be impatient. It will be convenient for the following work after the glue is removed.
The iPhone 6 display is black after replacing LCD. After checking, the diode data of display socket is normal and all power supply for iPhone display IC output is normal. Testing by DC power supply , we find the iPhone current is abnormal. When press the iPhone power button, the boot current is obviously large. The current reached 100mA when press the power button. After remove the display tube, the current still the same, which means there is a short circuit. Measure the voltage output of each circuit of power supply with Fluke 15B+ Digital Multimeter , then surprised to find that there are really short circuit places. LD010 is short circuit; we suspect that the filter capacitance on the circuit has been penetrated. After remove the iPhone power control IC , we found it is ground short circuit. Open the WUXINJI Dongle to check the iPhone schematic circuit, we found that this circuit is the display card image transmission MIPI data bus power supply. CPU brea...
The customer said that he did not know what the reason was. The mobile phone has been restarted indefinitely and can enter the DFU mode. However, when the flashing machine fails to enter the recovery mode from the DFU mode, and then the mobile phone is connected to the computer for 5-10 minutes, it automatically enters the recovery mode. After we received the 6S that could not be started, we disassembled the power with iphone engraving tool and turned on the power to 100mA. First of all, check if you can connect and read the DFU mode after connecting to the computer. Wireless DFU can not exit, we can only brush the machine to view the error. Refresh Aisi and iTunes respectively. If you stuck on the progress bar for a long time, it is very likely that the error is -1. If the progress bar does not enter, you can roughly determine the probability of a CPU failure. Now we need to see if there is a problem with the hard drive. First, use DC power supply for iphone repair, the hard disk o...
Since the size of iPhone6s plus screen display is large, it's necessary to use two sets of background lights to supply power, one is provided by U4020, the other is provided by U4050. 2 sets of circuit 1) PP_LCM_BL_ANODE, PP_LCM_CAT1, PP_LCM_BL_CAT2 2) PP_LCM_BL34_ANODE, PP_LCM_BL_CAT3, PP_LCM_BL_CAT4 For PP_LCM_BL_ANODE and PP_LCM_BL34_ANODE, if one of the circuit has no voltage value, it will cause the iPhone 6s Plus screen to be half bright and half dark. For PP_LCM_CAT1, PP_LCM_BL_CAT2, PP_LCM_BL_CAT3 and PP_LCM_BL_CAT4, if one of these four circuits gets abnormal signal, it will cause the 1/4 screen to be dark. Solution: Use jumper wire to short connect PP_LCM_CAT1 and PP_LCM_BL_CAT2 or you can also connect PP_LCM_CAT3 and PP_LCM_BL_CAT4. The control signals of these two sets of backlights, one group of inductors FL4211 FL4212 FL4213 are sent to the display interface. The other group is sent to the display interface...
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