iPhone 7 can't boot,cpu repair steps!
A week ago, the customer sent us an iPhone 7 that could not be turned on. After we received the device, we detected a short circuit on the iPhone 7 CPU. The following are the steps to repair it.
First use the iPhone open tool to remove the iPhone and disconnect the battery, then connect the phone to the DC power supply, the current reading of the ammeter jumps to 350 mA and then remains still, which is an abnormality, indicating that the logic board is shorted.
Disconnect power and remove the logic board. Measure the capacitors around the power IC one by one. Except C1823 all values are normal - 0 is displayed, which indicate a short circuit in C1823. Observe schematic with WUXINJI dongle(VC696) , C1823 is the filter capacitor of PP1V8-SDRAM, which is directly connected to the CPU SDRAM.
Connect the logic board to the PCB bracket, use QUICK 861DW hot air rework station to heat shield cover , and then remove the CPU SDRAM with a CNC chip grinder. After grind the chip, attach the logic board to the PCB holder and cleaned with PCB cleaner, and then the black adhesive is removed with graver scraper cutter. After that, apply BGA solder paste to the pads, and solder with a heat gun.
Connect the iPhone to a DC power source, then use tweezers to lead the pin 13 of the J4504 to ground to trigger system power. This time, the current read on digital multimeter is normal.
Assemble the logic board. Connect your iPhone to your computer, then turn off the volume and enter DFU mode, insert your SIM card and activate your phone.
After testing all the functions work well. Repair work completed successfully.
Do you have any problem about this article? Please contact us on www.vipprogrammer.com.
First use the iPhone open tool to remove the iPhone and disconnect the battery, then connect the phone to the DC power supply, the current reading of the ammeter jumps to 350 mA and then remains still, which is an abnormality, indicating that the logic board is shorted.
Disconnect power and remove the logic board. Measure the capacitors around the power IC one by one. Except C1823 all values are normal - 0 is displayed, which indicate a short circuit in C1823. Observe schematic with WUXINJI dongle(VC696) , C1823 is the filter capacitor of PP1V8-SDRAM, which is directly connected to the CPU SDRAM.
Connect the logic board to the PCB bracket, use QUICK 861DW hot air rework station to heat shield cover , and then remove the CPU SDRAM with a CNC chip grinder. After grind the chip, attach the logic board to the PCB holder and cleaned with PCB cleaner, and then the black adhesive is removed with graver scraper cutter. After that, apply BGA solder paste to the pads, and solder with a heat gun.
Connect the iPhone to a DC power source, then use tweezers to lead the pin 13 of the J4504 to ground to trigger system power. This time, the current read on digital multimeter is normal.
Assemble the logic board. Connect your iPhone to your computer, then turn off the volume and enter DFU mode, insert your SIM card and activate your phone.
After testing all the functions work well. Repair work completed successfully.
Do you have any problem about this article? Please contact us on www.vipprogrammer.com.
评论
发表评论