iPhone 6S Plus No Sound Fault Repair - Everything you need to know!

According to customer's description, when he played music on the iPhone 6S Plus, no any sound was sending from the iPhone speaker, but when plugging earphones the sound is normal , the ring bell doesn't vibrate, and the phonetic memo can be recorded. 

The first step is to judge the fault, if there is no speaker voice when playing music on iPhone, generally the fault is caused by iPhone audio amplifier chips. There are 2 Audio Power Amplifiers: U3700 and U3800.

Which chip is out of problem? The previous test has said that the vibration function is not normal. The vibration function is managed by U3800 chip. Therefore, we remove the U3800 chip to measure the ground resistance of the chip pad. It is found that the E7pin I2S_AP_TO_ARC_MCLK  ground resistance is infinitely great.

In WUXINJI schematic diagram, it is known that the signal passes through the R0921 resistance to the iPhone 6s Plus CPU. Picture 14-9-2

In the measurement, it is found that the CPU solder joint is broken down to the R0921 resistance layer. It is not easy to dig the route on the plate layer, so we try to borrow the 12S_AP_TO_CODEC_MCLK signal of the audio IC chip, soldering jumper wire from the R0920 resistance to the R0921 resistor. 

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Install to test, the sound is playing normal, vibration becomes normal and the sound of recording is also normal now! 

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