Analysis iPhone 6S audio and vibration fault step by step

Not each of iPhone same fault was caused by the same reason.

There still exist uncertain reason for phone fault, today we will share an article about iPhone 6S audio and vibration fault. Maybe you doubt the IC fault,  just following the below article:

We connected it with the DC power supply, test the audio IC one by one, we found some unusual,the receiver signal CODEC_TO_RCVR_N CODEC_TO_RCVR_P of the normal call mode comes out from the iPhone 6s audio IC, passes the FL3153 FL3154 to the receiver flex cable interface J3100, and then sends signal to the receiver to make a sound. There are two microphones in the normal call mode, one is LOWER MICI, the other one is LOWER MIC4. And there are two microphone signals, one is LOWERMICI_TO_CODEC_A1N1_P LOWERMICI_TO_CODEC_A1N1_N, and the other is LOWERMIC4_TO_CODEC_A1N2_P LOWERMIC4_TO_CODEC_A1N2_N.

After we compared it with the diagram shows, we know that the two sets of microphone signals pass the charger port flex cable, charger port flex cable interface J4600, and then respectively through inductance FL4610 FL4611 and FL3613 FL4614 to Audio IC--U3500. The microscope power sent by audio respectively pass inductance FL4612 FL4615 and then through the charger port flex cable to supply the two microphones.

Then we decided to enter the HF mode, to check the loudspeaker signal, it can directly see the speaker code.

SPEAKER_TO_SPEAKERAMP_VSENSE_P, SPEAKER_TO_SPEAKERAMP_VSENSE_N comes from ringtone amplifier IC--U3700, and passes the FL4630 FL4631, charger port felx cable to loudspeaker to make sound.

The hands-free microphone signal (the hands-free model microphone is on top of receiver flex cable) passes through the receiver flex cable interface J3100, passes through the inductor FL3155 FL3156 to the audio U3500, and the audio U3500 sent the audio U3500, the HF microphone power PP_CODEC_TO_FRONTMIC3_BIAS through the inductance FL3150 to the receiver's flex cable interface J3100, and then supplies to microphone through headphone flex cable.

As of the iPhone 6S was designed  a videotape microscope which is on top of the power, it also can cause the video or hear only murmur, so we need to enter the HF mode to check it.

The ringtone amplifier IC--U3700 damage. Besides the ringtone, it will cause no hearing, no vibration. The vibrator is controlled by U3700 and U3800. If there is no vibration failure, besides vibration and charger port flex cable, most of them are damaged by U3700 or U3800. Use PPD 861D+ Hot Air Station to remove the damaged part and replace new one will solve the problem.

Then we have checked it for many times, after we assemble it, if there is still no sound completely, just need to the audio U3500. But just part of the sound, check if the related inductance are dropped out, short connect by jumper wire, then directly replace it, it also can be solved.