While the no service fault always along with the SIM card, at the same time, SIM card along with the signal part and REFF bus, so we need to find the sources fault.
Obviously, we need to check it carefully, cuz it ask a disassemble. Following the steps:
Plug SIM card in, we can see the serial number when dial *#06# on dialing interface, as shown in 17-7-1, it seems that it is not the problem of the REFF bus, so we can exclude the fault caused by the bus (if the bus caused the fault, it will not show the serial number on the iPhone 6s Plus screen after dialing the *#06#).
Picture 17-7-1
From picture 17-7-2, we can see the operator option on the interface, there seems to be no problem with the receiving section. The problem is in the launch section.
Remove the iPhone 6s Plus logic board and measure by Fluke digital multimeter, we found the resistance value of PP_1V0_LDO9 was only 47, which was supplied to U_WTR_RF RF IC.
Remove the U_WTR_RF RF IC to measure again, the ground resistance value returns to normal.
Conclusion: the fault was caused by U_WTR_RF RF IC.
We just need to remove it, we will note it, how about you?
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