iPhone X Repair Experience Sharing for Intel Version.
As we know Apple was trying to change the modem gradually from Qualcomm to Intel, and even want drop Qualcomm’s Modem and keep Intel only. But after testing for some generations of iPhone, it’s found the Qualcomm Modem actually with better and more stable performance.
Let’s take iPhone X intel version repair as an example, there do have been a lot of Modem issues. And based on the repair cases, share some repair experiences with you.
Cannot Start-up
Normally the double-layers motherboard can be booted with the upper logic board only, however, when we boot the iPhone X intel version motherboard with the logic board only it will get into DFU mode and cannot startup.
In this situation, we can just simply jump a wire from S48 to S41 to borrow a 1.8 voltage. Then the phone can be booted normally.
Tips. The restart happens for iOS 11 only. For iOS 12 and above version, no need to jump wire and can startup with the upper logic board only. But when we solder back the two layers of motherboards, it will get into DFU mode again, need to restore with iTunes.
Cannot Start-up, AGAIN!
Sometimes another strange phenomenon is when you restore with upper layers only, the phone can be booted normally. However, once bonding back the two layers of the motherboard phone cannot start up again. The current curve is just the same as the DFU mode.
In this situation, don’t worry. It’s not the bonding problem, just need to restore it again then the phone can be booted normally.
No Service Issue
For the no service issue, based on the repair experience we will go to check the Transceiver IC. Without hesitation, let’s remove the SIM card tray connector first.
After that, measure the capacitors around the Transceiver IC, it is found the power supply of both the transceiver IC get shorted. The two chips share some power supply from Baseband PMU， there is a chance it’s caused by the Baseband PMU with then problem.
But to check the Baseband PMU, we need to separate the two layers of motherboards. Another possibility is one of the transceiver IC with problem cause another one also with power short. So in order to save time, we remove one IC first, then measure the diode value on the red circle marked capacitor, still short.
OK, continue to remove another one and measure the diode value again. The short is gone!
So finally confirmed that no service issue is caused by Transceiver chip damage. Replace them with a new one, then assmeble to test, service back to normal.
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