Recently, i heard many iPhone 6s owner said
that the volume button is out of work, that means iPhone 6S is unresponsive
when press the volume button. It make a lot of troubles for the owners. Now,
let's see what the problem is this
After checking circuitdiagram, we find that volume button
interface J4701 has three signal circuits, namely, volume up, volume down and
mute switch. The circuit diagram of J4701 socket is shown in picture 1-1.
1-1
Measure the voltage of pin 2,4 and 9 of
J4791. The voltage of volume up signal pin 4 BUTTON_VOL_UP_CONN_L is 0.6V while
the voltage of volume down signal pin 4 BUTTON_VOL_DOWN_CONN_L and voltage of
mute signal pin 9 BUTTON_RINGER_A_CONN are 1.8V. After checking circuit
diagram, we find that the three signals do not have pull-up resistors, which
suggests that CPU offer the pull-up voltage. Deenergize volume button interface
J4701 and measure the diode data of the four pins of J4701. The data is normal.
The low voltage of volume up signal BUTTON_VOL_UP_CONN_L could be caused by
electric leakage from some components on this signal circuit. Capacitor C4713,
voltage-regulator diode DZ4713 and CPU U0201 are connected with this signal, as
shown in picture 1-2. The material object is shown in picture 1-3.
1-2
1-3
The showing data indicate that CPU is not
pseudo soldering. Remove the capacitor C4713, voltage-regulator diode DZ4713
and measure the voltage of volume up signal BUTTON_VOL_UP_CONN_L. The voltage
remains the same. The diode data is normal. The voltage is abnormal even after
some parts are torn, which is obviously caused by a damaged CPU. We cannot
replace the CPU, but we can add a pull-up
voltage at the outside of CPU. After checking circuit diagram, it is the most
convenient to gain voltage from compass. Connect a 1kΩresistor at the 1.8V end
of capacitor C3000. Jump a wire from the other end of the resistor to the
un-grounded end of C4712, as shown in picture 1-4.
1-4
After the above steps, we measure the
voltage of volume up signal BUTTON_VOL_UP_CONN_L. The voltage is 1.76V.
Assemble the motherboard to tester
assembly, cover the volume cable and turn on to test. We can adjust the volume
normally.The iPhone 6s Plus ca nback to normal work.
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