RESOLVED iPhone 6s Plus volume button was unresponsive

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, lets see what the problem is this

After checking circuitdiagram, we find that volume buttoninterface 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.

 

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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 sig nal, as shown in picture 1-2. The material object is shown in picture 1-3.

 

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The showing data indicate that CPU is not pseudo soldering. Rem ove 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.

 

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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.