Aug 04, 2021
Hello guys, today we will walk you through the troubleshooting of a rare case of iPhone X not responding in sleep mode when getting incoming calls.
Go to Settings>Sounds&Haptics. All going well.
With the screen on, place a call to the phone using a known-good phone. The decline and answer buttons appear on the screen.
Turn the screen off. Place a call to the phone using a known-good phone. The phone is not responding at all. Press the power button to turn the screen on. We can see the decline and answer buttons on the screen.
Judging by this, relevant circuits of the baseband wake signal might have malfunctioned. Take apart the phone and disconnect the battery. Remove the display assembly and take out the motherboard.
Attach the motherboard to the PCB Holder. Heat with Hot Air Gun at 200℃, air flow 3. Tear off the heat dissipation sticker on the backside of the motherboard.
Open the bitmap software. Locate BB_TO_PMU_PCIE_HOST_WAKE_L. Since relevant circuits of the wake signal might have malfunctioned, we can try to borrow the wake signal from WiFi relevant circuits.
Locate WLAN_TO_PMU_HOST_WAKE. We can connect PP101_E-1 (the test point of the baseband wake signal) with PP7611_W-1 (the test point of the WiFi wake signal) by jumping a wire.
Scrape off the insulating coating on the two test points first. Then apply some solder paste to the two bonding pads. Heat with Soldering Iron at 365℃. Tin the two bonding pads with solder paste.
Connect PP101_E-1 to PP7611_W-1 with 0.02mm Enameled Copper Wire.
Then coat the wire with the UV Curable Solder Mask.
Now we can assemble the phone and test. With the screen off, test again. All going well. Fault cleared.
Apr 23, 2021
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