What cause iPhone 6 Plus has no service

Some users have complained that they see the No Service message on iPhone 6 Plus and has not been repaired well for several times.It does not show IMEI when dial *#06#, the fix for this issue has not changed ,There are a few different options to address this issue.

In “about iPhone” are IMEI, modem firmware, iphone Wi-Fi chip address, Bluetooth and ICCID, as shown in picture 1-59.

There are several reasons for no service. First, there is no baseband (no IMEI and modem firmware). Second, iPhone does not read the SIM card (no ICCID). Third, there are some problems in RF circuit. If dropped iPhones displays no service, components pseudo soldering or open circuit may cause the problem.

Therefore, we can conclude that no-service trouble takes place in RF circuit. Use multimeter to measure several main test points, finding out the diode data of testing point PP3170_RF is lager than the normal one 0.406. The location of testing point PP3170_RF is shown in picture 1-60.

After checking the schematic diagram, testing point PP3170_RF is the clock signal RFFE1_CLK of RFFE bus input by baseband CPU, in picture 1-61.

Checking the PCB bitmap and we can see RFFE1_CLK’s signal is sent to many chips. The components connected to RFFE1_CLK as in picture 1-62.

Removing these chips, we find many solder pads of these chips have dropped off from motherboard. Use enameled wire to connect these pins of dropped solder pads, as shown in picture 1-63.

Then paint green oil and reweld those chips. Measure the diode data of testing point PP3170_RF and now the data becomes normal. Assemble motherboard to assembly and power on to enter the system. IPhone displays IMEI normally when dial*#06#.

Screen top left corner shows China Unicom 4G network signal after inserting SIM card.

Dialing 10010 to test, the conversation is normal. Trouble is removed.