We received an iPhone 6 to repair, the prblem of this iPhone is the home botton doesnt implement the return function effect, which means the iPhone home button not working. We need to fix it!
After checking, weve ruled out external issues, we excluded the perip heral accessories issues and decided the problem is on the iPhone motherboard.
Use multimeter to measure whether the iPhone motherboard fingerprint socket J2118#3 pin has resistance, the data is normal. When measure the voltage, we found the BUTTON_TO_AP_MENU_KEY_L_CONN only has 0.6V, it is obviously been pulled down, the normal voltage is around 1.3V. You can check those pins on phone circuit diagram.
R0313 starts with 392K, now we change it to 10K resistance, and then measure it again, we found the voltage reached 1.4V, almost normal. So we assemble the iPhone and test it, we found its still no return function after we install the fingerprint button. However, when we use tweezers to press the J2118#3 pin ground, it can return. We suspect it is a fingerprint key problem.
After measuring, we found there is a 20K current limiting resistance on the BUTTON_TO_AP_MENU_KEY_L_CONN of fingerprint key. Decisively remove that resistor, and then use thephone soldering station to directly short connect them.
After finish the above steps, use phone screwdrivers to install the iPhone, power on it, enter the IOS system, and test the home button return function, not it works perfectly.
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