iPhone 11 Pro Max SIM card no serviecs fault maintenance

Failure model: iPhone 11 Pro Max.
Symptoms: SIM card no serviecs.
Customer description saidmobile phoneThere is a problem with no serviecs in use, and the signal is abnormal.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 1.

Maintenance process: after getting the mobile phone, it is found that the plug-in card displays no serviecs, and the signal is abnormal. Next, it is normal to dial *#06#IMEI in the dialing interface, then the RFFE bus is normal.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 2.

It is also normal to manually search and check the operator option, indicating that the signal receiving part is also normal.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 3.

Then the problem appears in the launch part. Next, let’s disassemble the machine for inspection. Remove the motherboard separate.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 4.

power amplifier was found in the inspection, and there was one VCC shorted to ground.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 5.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 6.

Next, we went to Current heating test to see where Short circuit was, and finally found that the filter Capacitor of VCC was damaged.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 7.

Pick out the tweezers directly, and the VCC to the ground diode value will return to normal.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 8.

iPhone 11 Pro Max SIM card no serviecs fault maintenance figure 9.

Do a good job of cleaning, re-test the motherboard welding, and install it. The startup signal returns to normal, the call is normal, and the maintenance ends here.