3. Analysis flowchart 3.1 Boot fail Boot fail Check the power key FPC Change the FPC solder ok Change the M/B Confirm the M/B current is too large Connect the USB, if the computer Re-download the SW can get the device Check if have 32KHz from 26M Check the 26 M TCXO...
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Exchange CPU U101 3.2 Touch panel fail CTP fail CTP test fail? CTP damage, exchange CTP fail Exchange CTP, test the CTP Exchange CTP workable? Re- mount the Check CTP connector & EMI filter mount connector & EMI ok? Filter Oscilloscope to check I2C signal Exchange CPU...
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3.3Charging fail 3.3.1 When use charger no charging display When use charger no charging display Exchange charger or USB Exchange charger cable workable? Exchange the battery and check Exchange battery the old battery voltage under 3 V Check the OVP IC, USB connectors and components are soldered around well? Exchange PMIC...
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3.4 Speak fail Speak fail Exchange Measure the impedance on receiver 32ohm for receiver Check spring receiver。 Check the speaker of schematic are soldered.。 Change the audio codec chip...
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3.5 No ring No ring Exchange Speaker, check ok? Check the speaker of schematic and the connectors are soldered. Check whether the audio amplifier Weld or damaged.. Re-welding and change it, try it again Change the audio codec chip...
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3.6 LCM fail 3.6.1 LCM no display when power on White screen or black screen no display, with bright Check the LCD FPC connection is OK, whether the phone properly reassembled FPC After change LCD,Check Display is normal Check MB schematic of LCD, pathway EMI device as well as welding supply on the motherboard to check whether it is normal, plus welding EMI filter.
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3.6.2 LCD backlight does not shine LCD backlight does not shine Check the LCD module of FPC is connected to the connector on the MB is good, what is normal reconnect After change the LCD backlight, check LCD backlight again. In the case of checking whether Backlight circuit there should be lit LCD 20V...
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3.7 The mobile is frozen The mobile is frozen Connected to a computer via a USB Update software cable, check whether the computer device manager device pop Check for 32 KHz signal? That from Welding try 26MHz 26 MHz crystal oscillator divider crystal oscillator Check the 26MHz crystal is normal? After welding, try...
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3.8 Power key & side key fail Power key & side key fail Check button FPC soldering & assembly, Re-solder or re-assembly Change FPC Push button & check the signal short to Change CPU...
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3.9 signal abnormal Signal abnormal Set phone to engineering Re-write SN\IMEI mode & check if SN\IMEI be wroten Re-assembly ANT connector Check ANT connector OK Check down load tool Re-download SW to see if information to locate the Download pass issue Check modem &...
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3.10 Receiver no sound Receiver no sound Change receiver Measure receiver resistance 32ohm Check receiver spring connection OK , re-assembly receiver Check receiver bead soldering, re-soldering & test Check audio codec power Re-soldering or change & soldering audio codec...
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3.11 MIC not work MIC not work Check MIC soldering & Re-solder MIC re-solder OK Change MIC ok? Check sub-board connection soldering & assembly OK? Re-soldering & assembly Re-soldering audio codec...
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3.12 Screen Mess Screen mess Check LCD FPC connection, Reassemble FPC if the phone is OK Replace the LCD,display is ok LCD fault Check the EMI Components on the LCD path of the main board and if the power supply is ok, Re-solder EMI filter Check the components around the LCD Re-solder them...
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3.13 Ring fail Ring fail Measure speaker impedance if Speaker fault, replace it is ok (8Ohm or 4Ohm) Check the speaker leaf spring if connect to the contact point well and Reassemble it. Check the bead in the receiver circuit if have a poor soldering, and re-solder it.
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3.14 Ring is low Ring is low Check audio NV and Re-download SW Speaker fault, replace Measure speaker impedance if ok (8Ohm or 4Ohm) Check the speaker leaf spring if contact the point well and Reassemble it. Check the bead in the receiver circuit if have a poor soldering and re-solder it.
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3.15 Can’t charge Can’t charge Replace the charger and Charger fault USB Cable Replace the battery if is ok? Replace battery Measure the battery voltage if is less than 3V. Check the OVP IC, USB connector and the components around the connector if have a poor soldering and re-solder it Replace the PMIC...
3.16 Camera fail 3.16.1 The rear Camera can’t take photos The rear Camera can’t take photos Teardown check whether the Camera module is separated from, reshipment module is OK Replacing Camera Module Check the connectors are soldered good , rework it Check EMI device is complete, the Rework it and try again welding is good?...
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3.16.2 The front Camera can’t take photos The front Camera can‘t take photos Open the phone , check whether Camera module Weld or re-welding module is OK Replacing Camera Module is OK Rework it and try again Check EMI device is complete, the welding is good?...
3.1.7 Auto Shutdown Auto Shutdown Check whether the battery has power, battery Charging the battery, replace the temperature detecting pin, connectors are in good condition connector Turned on the phone with the DC Source, Check whether the device has observe electric current Turned on the phone been damaged with the DC Source, observe electric current According to Download Tool tips,...
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3.18 No SIM No SIM Replace a new SIM card Check whether write Rewrite SN number and number and the IMEI number the IMEI number Teardown check the connection condition of RF antenna, can reassemble the general card Check the transceiver IC, PA and surrounding devices welding is good Replace Modem Chip...
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3.19 The M/B leakage of electricity The M/B leakage of electricity Electric leakage can be Plus electricity but does not boot, determined on VBAT then observing whether there is a which is supplying the large leakage current battery power directly Open the phone, Plus electricity and Screening the module boot it, then Touch all parts of the...