Xiaomi 6 earpiece has no sound, and it is left for silent repair

Xiaomi 6 earpiece has no sound, and it is left for silent repair

Hello, everyone. Welcome to Xunwei case sharing. First of all, I would like to thank Master Lai of Xunwei Technology Group for providing the example materials.
Machine model: Xiaomi 6
Malfunction: The mobile phone earpiece has no sound, and the sound of unstable is silent.
Maintenance process:
First of all, according to the fault performance, there is no sound in the external earpiece, which can completely eliminate the speaker damage and the fault point is transferred to the circuit of the motherboard coder.

Xiaomi 6 earpiece has no sound, and it is left for silent repair. Figure 1.

First, open the Xinzhizao Soft drawing, find the location labeling diagram of Xiaomi 6, and find the chip related to coder circuit.

Xiaomi 6 earpiece has no sound, and it is left for silent repair. Figure 2.
In the end, we each found an coder chip and coder power amplifier chip, because the speaker has sound, but the sound is abnormal. If the sound is abnormal, first suspect that coder power amplifier chip is damaged or working condition subsidy, open Boardview and circuit schematic, and measure the working condition of the chip according to the drawing data.

Xiaomi 6 earpiece has no sound, and it is left for silent repair. Figure 3.

Xiaomi 6 earpiece has no sound, and it is left for silent repair. Figure 4.

Through measurement, it is found that all the working conditions of the chip are normal, so we suspect that it may be due to the abnormality of the line through the CPU, such as the chip Inveracious Soldering or disconnection. Generally, maintenance is from easy to difficult. Therefore, we first tested Repeat welding and Repeat welding on coder power amplifier chip, and found that the fault was solved. So,The fault should be caused by the communication line coder power amplifier chip and CPU Inveracious Soldering.