Solutions for iPhone 6S Plus No Service

Fault Description:  iPhone 6S Plus happens no service when insert the SIM card.

While the attached file described it is possible to be caused by the WiFi failure,  cause he did the repair work before by himself. Meanwhile, we have tried to insert the SIM card, it is true like he said.

So here comes the question, we need to continue the testing. Following the test process.

Continue testing, the signal is normal when you turn on 4G in Cellular Data, it can connect to the 4G network. It's normal to make phone calls and browse the Web，but the signal is bad. Turn off 4G, and then choose 3G and 2G, both of them are showed no service.

The 4G signal can be searched normally, but 2G and 3G are no service, we suspected that the fault should be an iPhone antenna switch or a 2G amplifier.

Is it an error in the antenna switch frequency selection? We decided to replace the antenna switch and test it. After remove the antenna switch, use digital multimeter to measure the diode data, we found the 21th PP_2V8_LD014 power supply of the ULASM_FR antenna switch is grounding short-circuited.

Open the WUXINJI Dongle to check the iPhone schematic diagram, we found the PP_2V8_LDO14 is connected to many places, one of them was sent to the filter U_VOX_RF next to the iPhone WIFI IC.

Measuring the diode data for all the power supply of filter, we found there are several power supply circuit are short-circuited.

According to the description of the customer, we judged that the fault is that the tin ball of the filter next to the iPhone WIFI IC was burned when he repairing the iPhone WIFI IC.

Use QUICK 861DW hot air rework station and Titanium Alloy Tweezers to remove the U_VOX_RF directly，and then turn on iPhone to test, now the 2G, 3G and 4G signal can be searched normally, and the signal tested is normal.

After re-installing the U_VIX_RF, all functions are normal, the repairs end!