IPhone 6 Plus displays no IMEI when dialing *#06#. There is baseband firmware in “about iPhoneâ€. And iPhone keeps displaying “is searchingâ€.
Repair Process
Customer sends one board only. First assemble it to testing iPhone assembly and test. After power on, iPhone will display “no SIM card†without inserting SIM card. If that happens, there is modem firmware in “about iPhoneâ€(picture 1-40). That is to say, there is baseband.
Picture 1-40
Numbers on the back of modem firmware suggests there is baseband CPU. There is not baseband, if without numbers. Input*#06# on the dial interface w ithout inserting SIM card. If it is normal, the same IMEI in “about iPhone†will show up.
If there is no response and IMEI after inputting*#06#, in addition, there is baseband firmware, so the problem cannot be caused by baseband. Displaying no IMEI after dialing *#06# is often caused by the two RFFE bus of baseband. There are four test points under NAND Flash , as shown in picture 1-41.
Picture 1-41
The four test points do not reveal any copper. Therefore, we need to use a pointed probe Multimeter to measure or scrape them. The normal diode data is between 300-400. But the RFFE2_CLK (picture 1-42) diode data is 750 which is seriously high.
Pictu re 1-42
It is clear that RFFE2_CLK signal antenna is not normal. The diode data 750 comes from CPU. So the circuit breakage of baseband solder pad has been excluded. The normal diode data is about 400. The diode data of RFFE2 is from the DSM amplifier, and it probably caused by DSM amplifier’s U_DSM_RF pseudo soldering. The material object of DSM amplifier IC is shown in picture 1-43.
Picture 1-43
Reassemble DSM amplifier and measure the diode data of RFFE_CLK. Now the data is 380 that is normal. After power on, iPhone shows IMEI when dialing *#06#. Insert SIM card and the signal becomes normal, even for several days. The trouble is removed.
Repair Process
Customer sends one board only. First assemble it to testing iPhone assembly and test. After power on, iPhone will display “no SIM card†without inserting SIM card. If that happens, there is modem firmware in “about iPhoneâ€(picture 1-40). That is to say, there is baseband.
Picture 1-40
Numbers on the back of modem firmware suggests there is baseband CPU. There is not baseband, if without numbers. Input*#06# on the dial interface w ithout inserting SIM card. If it is normal, the same IMEI in “about iPhone†will show up.
If there is no response and IMEI after inputting*#06#, in addition, there is baseband firmware, so the problem cannot be caused by baseband. Displaying no IMEI after dialing *#06# is often caused by the two RFFE bus of baseband. There are four test points under NAND Flash , as shown in picture 1-41.
Picture 1-41
The four test points do not reveal any copper. Therefore, we need to use a pointed probe Multimeter to measure or scrape them. The normal diode data is between 300-400. But the RFFE2_CLK (picture 1-42) diode data is 750 which is seriously high.
Pictu re 1-42
It is clear that RFFE2_CLK signal antenna is not normal. The diode data 750 comes from CPU. So the circuit breakage of baseband solder pad has been excluded. The normal diode data is about 400. The diode data of RFFE2 is from the DSM amplifier, and it probably caused by DSM amplifier’s U_DSM_RF pseudo soldering. The material object of DSM amplifier IC is shown in picture 1-43.
Picture 1-43
Reassemble DSM amplifier and measure the diode data of RFFE_CLK. Now the data is 380 that is normal. After power on, iPhone shows IMEI when dialing *#06#. Insert SIM card and the signal becomes normal, even for several days. The trouble is removed.
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