Field mobile phone maintenance diary (1) scrapped iPhone does not turn on, no fingerprints, can it be saved?
Yang Hengchang 2021-06-09 04:11:23

Time flies by , In the twinkling of an eye, it has been a month since I came to Xunwei for field study , The second month began to officially enter Mobile phone instance maintenance stage , After the first month of theoretical and manual study , The teacher's careful teaching and his diligent exercise passed the exam smoothly , Get the breakdown machine , I'll never look blank again , I don't know how to start , You can repair the machine by yourself . This is the first time that field students have recorded that they have repaired their mobile phones (2 platform ) My experience and maintenance ideas , Let's take a look !

The first cell phone :iPhone6 Electric leakage maintenance

【 Machine model 】iPhone6 Fault board

【 The fault phenomenon 】 Electricity leakage


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

【 Maintenance process 】

Today, Mr. Su brought a batch of fault boards , When I get the fault board , Check the appearance of the motherboard , Found a small amount of water 、 A small amount of residual solder paste 、 Lack of CPU cover 、 There's even a lack of chips , I wonder if this motherboard gave up before it was repaired ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Connect the ammeter , Sure enough, the power leakage can't trigger .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Deal with the problem of electric leakage first , Consider whether the motherboard has been moved , Remove the remaining two shields and see which chip has moved . Remove the shield cover and accidentally touch the low frequency power amplifier chip and 2G Power amplifier chip , Take the two chips apart and put them first , Fix it and install it .

Observe the whole plate carefully under the microscope , I found a chip crack .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Cha Xinzhi made the drawings , Double open bitmap 、 Annotated drawing , Sure enough Baseband power chip , I wonder if it is the cause of electric leakage ? A multimeter measures the capacitance resistance around the baseband power supply chip , Find out One of the capacitance resistance values is grounded .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Remove the broken chip , Measure the capacitance of the short circuit , No short circuit, no resistance , It looks like the chip is broken .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Clean the motherboard pad , Connect the electricity , No more electricity , Return to normal standby current . Short circuit trigger , The ammeter shows a cheerful current , It looks like we've run the yard .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

iPhone6 Find a good baseband power chip on the substitute board , Remove 、 Replantation 、 welding 、 Hit resistance value OK, Short circuit again to trigger , The current jumps normally .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

Do you think you're ready for screen test ?NO~~~~ I said at the beginning , The display chip and the fingerprint power supply were removed . Remove and replant the display chip and fingerprint power supply chip on the disassembly board .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

After the installation , hold Low frequency power amplifier and 2G Power amplifier re installation , Connect to the test screen 、 Connect the electricity 、 Short circuit trigger 、 Perfect lighting ! Troubleshooting , That's the end of the maintenance .


 Field mobile phone maintenance diary ( One ) Scrap iPhone No power on, no fingerprints , There's still hope ?

summary : Watch the motherboard carefully , Find the suspect and fix it .

This case is organized by Xunwei students 【 Wood loves litchi 】 Original offers !

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