Wednesday, January 24, 2018

Best fix: No WIFI on iPhone 6 (PCB board disconnect)



 No WIFI on iPhone 6!  The iPhone 6 has been serviced twice since there are no wifi problems, but it hasn't been repaired. What's going on?  We need to fix it .

Disaasemble the iPhone, we can see there are lots of solder flux  cover on WiFi, it seems that WiFi has been replaced several times, a nearby resistor is also lost , the bottom of WIFI is scraped to copper wire, we can certainly confirm it's not the iPhone 6 WIFI module problem.

Then remove the WIFI and boot device to measure the voltage of WIFI bottom board pin, we find that 14 pin has no signal voltage, it should be 1.8V. The problem comes from here. Using a digital multimeter to measure but no resistance, so we use WUXINJI bitmap to check and find it is directly through CPU, is it the bottom board wire disconnection? After checking, the iPhone 6 bottom board wire is really disconnected.



Now we have to see if there is another way, continue to look at the principle diagram Apple 6.



This reset signal has a capacitor and a pull-up resistor. The capacitance is next to WIFI. There is no resistance in the measurement. This is hopeless, then we look at the pull-up resistor again, find it is on the back of the iPhone 6 CPU from the bitmap, and it's very close. Measuring resistance is 446, then directly solder jumper wire, install WIFI, but the icon is still gray. Then we think the WIFI may be broken. Immediately replace a new WIFI chip.



Now, install the iPhone to test it. After booting,  the Bluetooth can be used now, and the WIFI is shown up!

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