Received an iPhone XR no boot.
Once received, connect with DC power supply machine to test, test result with around 1A current leakage.
Since the current leakage happens once connected with DC power, the short might come from the below rails
- PP_BATT_VCC
- PP_VDD_MAIN
- PP_VDD_BOOST
And the XR board is similar to the iPhone 8Plus and below models. So based on repair experience, we can use the rosin inspection method or use the thermal imager to find out the damaged or shorted components.
But before using the rosin inspection method or the thermal imager, in order to narrow the range of defect location, we can apply DC power and simply feel with a finger first.
After checking, we found the chips and components around the audio amplifier IC are hotter.
Then apply rosin and check again, the rosin on the audio amplifier IC gets melted.
Normally, we can go to the audio amplifier IC, and replace it with a new one directly.
But in this case, the audio amplifier IC is very close to the CPU, replacing the chip with some risk to get the CPU pseudo soldering. Also the audio amplifier circuit with many powers, the capacitor short can also lead to components being extremely hot.
So based on repair experience, check the small capacitors around the audio amplifier IC first.
After checking, we find a small capacitor is shorted. The location as arrow marked
And check the Refox bitmap the capacitor is relative with the PP_SPKAMP_TOP_VBOOST
Remove the capacitor and check the startup current, the current value is back to normal.
Then put back a capacitor with the same specification, check again, the phone can be booted up normally.
Assemble the phone and test, all the functions are OK.
Tips:
when chips and components get hot at the same time, check small components condition first. Like this case, iPhone XR no boot finally gets fixed by capacitor replacement.
