{"id":2015,"date":"2018-03-21T00:00:00","date_gmt":"2018-03-21T00:00:00","guid":{"rendered":"http:\/\/192.168.2.19:8666\/?p=1"},"modified":"2024-09-18T18:25:26","modified_gmt":"2024-09-18T10:25:26","slug":"fix-iphone-7-wont-power-on-cpu-repair","status":"publish","type":"post","link":"https:\/\/rewa.tech\/fr\/fix-iphone-7-wont-power-on-cpu-repair\/","title":{"rendered":"Troubleshooting iPhone 7 Won’t Turn On"},"content":{"rendered":"

What should you do if your iPhone 7 won’t turn on after being dropped?<\/p>\n

The problem may be caused by a software crash or a complicated hardware issue.<\/p>\n

We have published an\u00a0iPhone 6 won’t turn on\u00a0and iPhone X won’t turn on guide video, and this time, we received an dropped iPhone 7 Plus which cannot turn on.<\/p>\n

The problem was finally detected as CPU being short-circuited. Here we have detailed troubleshooting procedures.<\/p>\n

\"Fix<\/p>\n

iPhone 7 won’t turn on Diagnosis<\/p>\n

Take apart the phone and disconnect the battery, then connect the phone with the Alimentation en courant continu<\/a> and press the power button to power on.<\/p>\n

The current reading of the ammeter jumps to 350mA and then stays still, which is abnormal and indicates that the logic board is short-circuited.<\/p>\n

\"Fix<\/p>\n

disassemble the phone and detach the battery<\/p>\n

Disconnect the power supply and take out the logic board.<\/p>\n

Run diode measurements on capacitors around power IC one by one.<\/p>\n

All the values are normal except\u00a0C1823 – It displays 0, which indicates that C1823 is short-circuited.<\/p>\n

From the schematics<\/a>, we can see that C1823 is the filter capacitor of PP1V8-SDRAM, and it is directly connected to CPU SDRAM.<\/p>\n

\"Fix<\/p>\n

diode measurements on capacitors around power IC Repair<\/p>\n

Fixez la carte logique au Support de carte de circuit imprim\u00e9<\/a>, and take down the shielding cover by heating with Hot Air Gun, then remove CPU SDRAM with Machine \u00e0 rectifier les copeaux \u00e0 commande num\u00e9rique<\/span>.<\/p>\n

After chip grinding, attach the logic board to the PCB Holder and clean it with PCB Cleaner, then remove the black adhesive around with Sculpture Knife.<\/p>\n

After that, apply some BGA Paste Flux to the bonding pad.\u00a0<\/p>\n

Align the new SDRAM to the right place(Don\u2019t reverse the direction),\u00a0and then solder with Hot Air Gun. After cooling for 5 minutes, clean thoroughly with PCB Cleaner.<\/p>\n

\"Fix<\/p>\n

CPU SDRAM chip grinding Testing<\/p>\n

Connect the phone with the DC Power Supply, then short Pin 13 of J4504 to the ground with the tweezer to trigger the power on the system.<\/p>\n

This time, the current reading on the ammeter is normal.<\/p>\n

\"Fix<\/p>\n

connect the phone with the DC Power Supply<\/p>\n

Get the logic board assembled and buckle the display assembly.<\/p>\n

Connect the phone to the computer, then press and hold volume down and power button to get into DFU mode. Restore the phone via iTunes.<\/p>\n

Once done, insert the SIM card and activate the phone.<\/p>\n

After testing, All the functions work normally.<\/p>\n

\"Fix<\/p>\n

current reading on the ammeter<\/p>\n

For more details about iPhone 7 won’t turn on repair and iPhone repair videos<\/span>, please check our YouTube video.<\/p>\n

Need cell phone repair replacement parts or tools?<\/p>\n

REWA offers wholesale and retail mobile phone repair parts\/tools with affordable prices for 10 years. Welcome to check our online store shop.rewa.tech<\/a>.<\/p>\n\n\n