How to Fix iphone 6 Plus Screen Turn Black Suddenly
1. How to Fix iphone 6 Plus Screen Turn Black
Suddenly
Generally, power issues would start at your iphone 6 plus,
today I will explain how to check and repair you turned
black screen iphone 6 plus. You can follow my step to try
fix. If you need some cellphone repair tools, you can try
vipprogrammer.com. Hoping it is helpful with you.
Issue:
IPhone 6 Plus suddenly turns black under normal use and
the display and touch screen power chip and main power
chip have been replaced. Repeatedly turn it on and off
and get into IOS test. IPhone can display only once, but
it turns black in a minute.
Repaird:
1. According customer’s feedback, we presume that the
CPU is pseudo soldering. Let us put the experience aside
and measure the working condition one step by one step.
The customer only sent one motherboard. We use it to
connect the display screen that is going to be tested and
2. plug adjustable power supply to turn it on. The current is
above 1A, but the display screen is still blank.
2. Measure the working condition of the two ±5.7V
voltages display screen circuits PP5V7_LCM_AVDDH
and PN5V7_SAGE_AVDDH and find that there is no
voltage. The two voltages were not produced normally
generally because the working condition of display
screen has not been satisfied or does not communicate
normally with CPU.
3. After removing the display screen, turn iPhone on and
measure the pin 35 1.8 V voltage and pin 26 I2C bus
voltage of display screen socket J2019, no problem has
been found. The circuit diagram of display screen socket
J2019 is shown in below picture.
3. 4. Unplug the power supply, measure the diode data of
display screen socket interface and compare the data with
that of a normal motherboard, finding no problem. The
bitmap of display screen socket is shown in below
picture.
5. After the above measurements, nothing wrong has
been found. However, the two ±5.7V voltages display
screen circuits PP5V7_LCM_AVDDH and
PN5V7_SAGE_AVDDH are still not produced. Thus,
CPU or the display and touch screen chip have
something wrong. First measure the pull-down resistor
4. R0702 of 45_LCM_REXT signal. If the pull-down
resistor R0702 is damaged, the MIPI mode used to
communicate between CPU and display screen will not
work. The circuit diagram of R0702 and the location of
R0702 in bitmap are shown in below picture.
5. 6. One end of the pull-down resistor R0702 is connected
to ground and the other is connected to pin A7 of CPU.
Measure diode data of the end towards CPU is 700 and
after careful observation, there is no mark of pseudo
soldering. As the customer changed the display and touch
power supply chip in the process of previous repair, the
next testing points are lying on the display and touch
power supply chip. The real material object of display
and touch power supply chip is shown in below picture.
6. 7. Teardown the display and touch power supply chip
and measure the diode data to ground of display and
touch power supply chip solder pad. The data is normal.
Replace a tested-workable display and touch power
supply chip and turn iPhone on. The white Apply logo
can be shown normally, but it turns black in a few
seconds.
8. Reboot it and the result is still the same. when
teardown the display and touch power supply chip, the
board of motherboard is heated. Does it become
abnormal after it cools down?
9. Teardown the display and touch power supply chip
again and blow the display and touch power supply chip
by a cooling fan for 10mins. When it cools down
completely, measure the diode data and we find the data
still exists. However, experience tells us that if the diode
data is normal, the voltage is not necessarily normal.
Plug power supply and turn iPhone on. Measuring the
voltage of several important signals on display and touch
power supply chip solder pad, now we find something
7. wrong. The voltage of pin C2 of display and touch power
supply chip U1501 is changing constantly. Pin C2 is
RESET_1V8_L which is the reset signal connected to
CPU.
10. Under normal circumstances, after turning on, the
voltage of the pin is a balanced 1.8V voltage rather than
a changing voltage. There is only one possibility that
causes the unbalanced voltage. The board of
motherboard has something wrong. The location of
RESET_1V8_L in bitmap is shown in below picture.
11. Reset signal RESET_1V8_L is connected to testing
point TP2508 near the EEPROM, as shown in below
picture.
8. 12. Measure the voltage of the testing point TP2508 is
1.8V which is normal. Measure this point and pin C2 of
display and touch power supply chip, we find that the
two points are disconnects. Thus we are sure that the
circuits in the board of motherboard are broken. Solder a
wire from testing point TP2508 to pin C2 of display and
touch power supply chip. After turning iPhone on and off
many times, the display screen function is normal.
Trouble is removed.
