There is a bad connection for wires with circuit board screws, nothing displayed on screen after iPhone turning on. Our client mentioned his iPhone 6 the problem remains same though it is repaired before. How to fix motherboard broken wires to get normal work?
First we tear it down and find three screws are twisted deeply. The problems are no backlight, no display and no ±5.7V power supply of screen. Observing under microscope, we find that the four circuits under those screws are disconnected.
One of the four circuits is the open signal LCM_TO_CHESTNUT_PWR_EN of display power supply chip. This signal connects power supply chip U1202.
The signal LCM_TO_CHESTNUT_PWR_EN connects display power supply chip U1501
The signal LCM_TO_CHESTNUT_PWR_EN connects display socket J2019 through the inductor FL2035
After measuring, display socket has no diode data, which suggests that it is disconnected. We have to jump a wire.
After it can display, we measure other function and find that the receiver has no sound, but the diode data to ground of receiver is normal. Remove the audio chip (U0900) and measure the diode data. We find that pin C9 is disconnected. Pin C9 is connected to CPU (U0201).
Because CPU has not been fixed before, we guess that the disconnection of the circuits under screws causes the problem. Find a bare motherboard and scratch its surface (called grinding, as shown in the picture). Thus we know that the second layer (arrow in the picture) under screw causes problem.
Next we jump a wire from audio chip pin C9 to the point that we find by grinding. At last, we paint UV Solder Resist to solidify it.
The process of soldering other jumping wires on PCB I would skip here, there are more than 10 wires in total. Finally iPhone can be turned on and display normally. We are happy that another cellphone fault is solved again!
Well! Best wishes to your cell phone repair! More professional skills read at www.vipfixphone.com
First we tear it down and find three screws are twisted deeply. The problems are no backlight, no display and no ±5.7V power supply of screen. Observing under microscope, we find that the four circuits under those screws are disconnected.
One of the four circuits is the open signal LCM_TO_CHESTNUT_PWR_EN of display power supply chip. This signal connects power supply chip U1202.
The signal LCM_TO_CHESTNUT_PWR_EN connects display power supply chip U1501
The signal LCM_TO_CHESTNUT_PWR_EN connects display socket J2019 through the inductor FL2035
After measuring, display socket has no diode data, which suggests that it is disconnected. We have to jump a wire.
After it can display, we measure other function and find that the receiver has no sound, but the diode data to ground of receiver is normal. Remove the audio chip (U0900) and measure the diode data. We find that pin C9 is disconnected. Pin C9 is connected to CPU (U0201).
Because CPU has not been fixed before, we guess that the disconnection of the circuits under screws causes the problem. Find a bare motherboard and scratch its surface (called grinding, as shown in the picture). Thus we know that the second layer (arrow in the picture) under screw causes problem.
Next we jump a wire from audio chip pin C9 to the point that we find by grinding. At last, we paint UV Solder Resist to solidify it.
The process of soldering other jumping wires on PCB I would skip here, there are more than 10 wires in total. Finally iPhone can be turned on and display normally. We are happy that another cellphone fault is solved again!
Well! Best wishes to your cell phone repair! More professional skills read at www.vipfixphone.com
评论
发表评论