An iPhone 6 stopped turning on after being dropped in water. The repair technician used various diagnostic techniques to identify the cause of the failure. They found that the display power supply chip was causing an electricity leakage on the I2C0 bus, preventing the phone from powering on fully. By removing and replacing the damaged display power supply chip, the phone was able to power on normally again.

1. My iPhone 6 dropped into the water and couldn't
turn on
Nowadays the smartphones are one of the important
things that in our life. We preserve our important data,
files, images and videos to our iPhone. But if you
accidentally drop your iPhone in the water, what can you
do? Don't worry, Now vipprog can help you tide over
difficulties.
Issue:
IPhone 6 cannot be turned on after dropping into water.
Solution:
1. Remove the screenand battery and plug adjustable
power supply to energize it. The current is 60mA. When
press the power button, the current stops at about 120mA.
Remove all the shield covers and find that some of
capacitors of the main power supply PP_VCC_MAIN
turn black.
2. Based on the circuit principle, we must figure out
whether the electricity leakage is from the circuits of
battery power supply PP_BATT_VCC or main power
supply PP_VCC_MAIN. First we remove the field-effect

2. transistor Q1403 that converts battery power supply into
main power supply. The Q1403 in schematics diagram is
shown in picture 1-1.
3. After removing Q1403, plug adjustable power supply.
If it still leaks, the circuits of battery power supply
PP_BATT_VCC leaks. If it does not leak, the circuits of
main power supply PP_VCC_MAIN leaks.
4. Energize it and test. The voltage-stabilized power
shows no electricity leakage. Based on repair experience,
for water-damaged iPhones, we first consider display
power supply IC, backlight IC and main power supply as
well as capacitor (The electricity leakage from the filter
capacitor at the circuits of main power supply
PP_VCC_MAIN cannot lead to turn on failure).

3. 5. Assemble Q1403 and put a thin layer of rosin on the
surrounding parts of display power chip U1501 and
backlight chip U1502. Then energize to find the hot
components. The display power supply chip and
backlight chip with rosin is shown in picture 1-2.
6. After few minutes, we notice that the rosin is not
burning. If the electricity leakage is from capacitor,
function chip or baseband chip, we could fix first and
then turn on to test its function. Use the problems from
functional circuits to ascertain a general faulty area.

4. 7. The motherboard has 120mA current that minus the
leaked 60mA. That means when at the moment iPhone
turned on, its current is 50~60mA which is caused by the
damaged circuits at the working condition of CPU, I2C0
bus, I2C1 bus and large power supply chip U120.
8. Energize iPhone and measure all the power supply of
CPU. All the power supply voltages are normal except
the voltage PP_GPU (This voltage can be measured only
when iPhone is turned on normally). Then we measure
the I2C bus and find that the voltage of
AP_TO_I2C0_SCL is 0.3V. This kind of trouble
phenomenon can be found only by measuring the diode
data to ground. If the diode data to ground of I2C bus is
high while the voltage of I2C bus is low, the pull-up
resistor and CPU have some problems. If the diode data
to ground is pulled down or short circuit, we have to tear
down the chips one by one to judge. We can measure the
I2C0 bus circuit at resistors R0302 and R0303. The
pull-up resistors R0302 and R0303 at I2C0 bus in bitmap
are shown in picture 1-3.

5. 9. Deenergize iPhone and measure the diode data to
ground of AP_TO_I2C0_SCL. The data is 33. I2C0 bus
flows to CPU, display power supply IC, backlight power
supply IC, USB chip and large power supply.
10. After water getting in, that the diode data to ground
of I2C0 bus is pulled down is often caused by displays
IC and USB chip. First remove display power supply
U1501 and energize iPhone to test. The electricity
leakage disappears. Short connect it and turn on. T he
adjustable power supply shows 1A current. The current
jump turns normal and iPhone can be turned on normally.

6. Remove a display power supply chip U1501 from
accessories board and assemble it on this faulty
motherboard. Triggering it on, the white Apple loge
appears and it enters boot screen. The display power
supply chip U1501 in schematics diagram are shown in
picture 1-4.
11. If the hot parts cannot be found, we can leave it and
skip to fix the problem of turn on failure. In most cases,
if the problem of turn on failure disappears, other
problems will disappear too. Or if the problem of turn on
failure disappears, but some function is still unworkable,
we can find the faulty points by entering IOS and testing.