We received an iPhone 6S Plus to repair, the issue is that there is no sound when the iPhone plays music, but after insert the earpiece, we can hear sound. What's going on? Here is the troubleshooting tips for it.
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.
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, use QUICK 861DW to solder jumper wire from the R0920 resistance to the R0921 resistor.
After finish the above step, assemble the iPhone, get into IOS to test, now we can hear sound normaly from the speaker , the vibration and recording also works good. The repairs end!
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