Recently we had an iPhone 7 in from a regular that had the classic audio IC symptoms of C12 pad damage. The phone would take a few minutes to boot, hung on the apple logo with home button vibrations, once booted it was very slow and we could not record voice memos. We also couldn’t hear on the phone and loud speaker was greyed out.
So we went about repairing the C12 pad damage as usual on any iphone 7 audio IC repair. When we lifted the IC up off the board there was no damage to any of the usual traces, all pads where firmly in place. We ran jumpers as normal anyway, reballed the IC and refitted it to the board. Unfortunately there was no change! We then removed the ic and replaced it incase the chip itself was faulty. This made no change either! We then checked the components around the audio IC and found the the resistor R1103 off of the C12 pad was faulty and needed to be replaced. We have done hundreds of audio ic repairs, and this was the first time we have seen it caused by this faulty resistor.
We tested the phone which was all working again, we then cleaned the board and reassembled the device. It was returned to our customer who was happy to have it back.
We have never seen this resistor cause audio IC problems before, but now that we have we will always check this before removing the IC, we don’t know if the IC was faulty too or if it was just this resistor all along but we know for sure that next time we see this faulty resistor we will find out.
The reason we love board level repair is because you can always learn something new, like when a classic repair turns into something a bit different for a change it makes your mind work a little bit harder.