What is the iPhone white screen and how to solve it_Hardware Repair

Do you encounter the situation that the iPhone white screen problem? Well, in this article we are  going to share with solutions to deal with some common issues of iPhone turn on with the white screen. Let’s find out the faults together now.

Example of iPhone White Screen Problem 1:

iPhone 6 turn on with the white screen and restarted repeatedly

 

iPhone White Screen Failure Phenomenon 1:

After starting up the iPhone 6, the screen is in white and it keeps restarting

 

iPhone White Screen Maintenance Procedures 1:

First, to recover the phone to eliminate the software problem. Enter into DFU mode, when the phone was recovering, the system reported the error code 9 as soon as the processing bar displayed on the screen. Using the multimeter to measure the ground impedance values of

pull-up resistor R0316 and R0317 of the I2C bus located upon the fingerprint chip U3001. The position of resistor R0316 and R0317 in the bitmap are shown as Pic 2-1. The ground impedance values of resistor R0317 was around 460 and 730 of resistor R0316. Obviously, the ground impedance values of resistor R0316 was larger. Both resistor’s signal was leading to CPU, so we could judge the failure is caused by the CPU. Removed the CUP and it was found that there were some corresponding points with broken circuits (shown as Pic 2-2). We had to wire the lines and reset the CPU. Then turn on the phone and the current is normal. After the touch panel assembled,  and enter in the system directly and test the function. Everything was fine in the test, so this issue solved.

The position of resistor R0316 and R0317 in the bitmap  Pic 2-1

The position of resistor R0316 and R0317 in the bitmap  Pic 2-1

The position of CPU broken circuits in bitmap  Pic 2-2

The position of CPU broken circuits in bitmap  Pic 2-2

 

 

Example of iPhone White Screen Problem 2:

iPhone 6 Plus turns on white screen, and it keep restarting after showing LOGO

 

iPhone White Screen Failure Phenomenon 2:

Informed by the customer that the phone could have been turned on, but seeing the shell was a little bent he broke off it with hand then the phone rebooted with the white screen and reported the error code 9.

 

iPhone White Screen Maintenance Procedures 2:

Boot test, when Apple LOGO appears, cell phone reboots.

Based on the previous experiences, white screen and reboot are more likely caused by the damage of the CPU, Chip, and hardware. Moreover, according to the customer’s description that the phone was broke off with hand, we could basically conclude that the man-made operation caused the CUP missing solder or dropping, so we have to re-weld the CPU.

After removing the CPU, it was found that there a circuit led to the chip was broken. The position of the broken circuit was shown as Pic 2-10. Moreover another circuit to the pad was not stable, so we had to directly fly the line to the relative pin of the chip.

 Removing the CUP, circuit led to the chip was broken   Pic 2-10

Removing the CUP, circuit led to the chip was broken   Pic 2-10

Welding the line on CPU pad, shown as Pic2-11

Flying the lines on the pad  Pic 2-11

Flying the lines on the pad  Pic 2-11

After welding the lines, weld the lead lines to pins of the chip with the help of the microscope. Shown as the Pic 2-12.

Welding the fly line on the chip under the view of Microscope   Pic 2-12

Welding the fly line on the chip under the view of Microscope   Pic 2-12

After finishing the fly line, re-weld the CUP. Shown as Pic 2-13.

The CPU was re-welded  Pic 2-13

The CPU was re-welded  Pic 2-13

After the CUP welded, the phone could be recovered successfully and enter into the activation interface of the system. The problem solved.

 

 

Example of iPhone White Screen Problem 3:

iPhone 6S Plus keep restarting after power on with white screen

 

iPhone White Screen Failure Phenomenon 3:

The phone rebooted with the white screen after fell, and the phone was repaired once but the problem didn’t fix.

 

iPhone White Screen Maintenance Procedures 3:

First checking the error code by recovery, iTunes recovery reported error code 4103. With other recovery software, it can show UDID info. Normally, if iPhone 6S Plus rebooted with the white screen and with error code 4103 were caused by the damage of the hard disk, however, this phone could show UDID info, which means the possibility of a hard disk failure was very small.

After disassembling, it was found that the motherboard was badly handled. The CPU, hard disk, and USB chip were all welded. First, clean up the soldering paste then check if there any missing parts on the welded places under the microscope. If there were no missing parts, replaced the hard disk and had the phone recovery. But it still reported error code 4013, according to our experiences, we could conclude that the possibility of a CPU failure was very small.

We checked the previous repair notes, there was a short circuit failure of the iphone6S power supply. The problem still existed even after we removed the baseband power chip but everything was back to normal after we replaced the baseband power chip. We had studied the operating principle of iPhone and found that the baseband chip of iPhone 6S is using the PCIE bus to communicate with CPU. During the boot process, the PCIE is initialized. So if the baseband could not work properly, the iPhone will reboot with the white screen.

We found another proper functioning iPhone 6S and had its recovery. We measured the baseband’s power supply when it turns on the white screen. It was found that the power supply has been generated and the preparation conditions for the baseband to work also satisfied. The position of the baseband power supply in the bitmap is shown as Pic 2-18.

The position of the baseband power supply in the bitmap    Pic 2-18.

The position of the baseband power supply in the bitmap    Pic 2-18

U3010 accelerometer damage will cause games stutter and crash.

U3030 gyroscope missing welded or damage will cause non gravity induction.

Baseband IC missing welded or damage will cause no serial number, no signal, no recognization on card and silent calls etc.

Power supply IC damage will cause no signal or can not make a phone call, Off and on calls call , and will cause electric leakage and large electric current.

 

Then we had the defective board recovery and also measured the baseband’s power supply in the presence of white screen. It was found that PP_0V9_SMPS1, PP_1V0_SMPS3 power supply generated while PP_1V225_SMPS2, PP_1V85_SMPS4 is not, which means that the power supply was with no problem and it was likely to be the baseband chip missing welded or damaged. The power supply circuit of the baseband is shown as Pic 2-19.

The baseband power supply circuit diagram   Pic 2-19

The baseband power supply circuit diagram   Pic 2-19

After removing the baseband chip, then measured the baseband chip and the ground impedance values of CPU and it showed in the normal range. Then we could weld the baseband to the motherboard after stannic planting. Had the phone recovery again and everything was back to normal. The problem solved.

 

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