No audio or audio controls on prior work

Question

iPhone 7

Lanzado en Septiembre 16, 2016. Modelos 1660, 1778. Disponible en GSM o CDMA / 32, 128, o 256 GB / Oro Rosa, Oro, Plata, Negro Mate y Negro Brillante.

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Nathan @nathanjohn

Rep: 191

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Publicado: 16 de feb. de 2021

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No audio or audio controls on prior work

I have received an iPhone 7 that has been worked on before (badly). The faults were two fold, the first was no rear camera, this was the LDO near the Wifi IC which has been repaired by a previous tech. This tech also did an audio IC repair but has made a bit of a mash of it. ALL of the Pads along the top edge are missing. I have jumpered these are ALL of the diode readings are good without the IC on. I have replaced the Audio IC 3 times with new chips and still the problem exists. I have also replaced the speaker AMP next to tristar and the all diiode readings are good too.

The problem is there is no audio, no mic input from the voice memo app and the volume buttons do nothing. Also there are no sw volume controls. I have also restored IOS twice.

I am thinking that something is screwing with the I2S bus and before I start replacing the other amps and Maggie (which I have never had to do before) I was wondering if there are any other suggestions? All other features of the device seem to be working fine. (Oh and I have tried a different housing as well, so the fault is on the logic board

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Chris Stables @imicrosoldering Rep: 50.7mil 8 14 101 · Answer 1 · 2021-02-16T15:14:01-07:00

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Chris Stables @imicrosoldering

Rep: 50.7mil

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101

Publicado: 16 de feb. de 2021

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This is why I have stopped doing prior repair attempts. Assuming you know how to microsolder and the IC is going on correctly I would

· Check R1103 and make sure it hasn’t been nudged off the back pad. The diode reading from C12 might seem okay even when R1103 has been nudged from the back pad but you will still have greyed out audio. This would be the most likely scenario.

· Check the reset line at R3201 again check it hasn’t been nudged off the back pad.

· Check the boost circuit. I usually give the IC a small nudge after it positions itself to make sure these pads are soldered correctly.

I have also seen a faulty speaker amp to cause this but I would be looking at the prior repair attempt.

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Thanks for the reply Chris, much appreciated. I may not have been that clear in my question. Yes, I am a proficient micro-solderer and like you I try and give the IC a little nudge. The actual fault is not only a greyed out loudspeaker (well it is greyed out), but there is no sound at all from anything. R1103 and R3201 are fine as are all of the diode mode readings. I have had to rebuild this area and it’s all good now. I have also replaced the main speaker amp and I still get no sound. I have done countless audio IC repairs but never seen no sound at all. I think that even when the IC is off the board you will still get sound such as ringtones etc., but here nothing.

I am thinking that this is something to do with the I2S lines that are used to communicate between all of the devices (x3 speaker amps, audio IC, Maggie and CPU. Perhaps one of these is not doing it’s thing. I do not know the circuit well enough but may have to start taking off / replacing these to see what happens.

If anyone can confirm my belief that a missing Audio IC still allows ringtones that would be great. My understanding is that the Audio IC is mainly used for mic inputs and not audio out (that goes from CPU / Maggie to the correct speaker amp…..

Thanks once again Chris

17 de feb. de 2021 - de Nathan

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