1. SMART PHONE © 2018. DesignTech Systems | Confidential | All rights reserved.

2. INTRODUCTION  A smartphone is a portable computer and pocket sized hand held device.  Smart phone provides advanced features like internet browsing, video calling, online video streaming, video games, GPS navigation, Fingerprint lock etc..  Thus, there is consequent need for the skilled professionals carry out the repair and maintenance of smart phone. © 2018. DesignTech Systems | Confidential | All rights reserved.2

3. COMPONENTS OF SMART PHONE  Loudspeaker: It is an audio signaling device which consists of electrical connection for direct mounting on printed circuit board.  Speaker: It is a small sound driver fitted within a mobile phone to produce sound.  Headphone Jack: This jack is a connector in which the pin-shaped plug of the headphones is plugged in. (3.5mm)  Power Button: It is used to turn the smart phone ON and OFF.  Volume Button: Volume buttons are used to increase (or) decrease the volume of the smart phone.  Internal mid frame: It consists of a motherboard and a daughter board.  Mother Board: Front side of the motherboard consists of daughter board, the daughter board consists of a microphone. © 2018. DesignTech Systems | Confidential | All rights reserved.

4.  Micro phone: It is a magnetic device which converts the sound waves like human voice in to electrical signals.  Multipurpose Jack: It is usually provided to connect USB cable and to charge smart phone.  Antenna coaxial cable: Antenna coaxial cable connects the antenna to the standard wide band code division multiple access or WCDMA(3G)---- “It is a way of sending information in air (Radio access technology)  While 4G uses “ OFDMA” technology(orthogonal frequency division multiplexing) it is a technique for transmitting large amounts of data over a radio wave.  Flash light: Smart phones are designed with flash light at the rare side to take pictures at low light conditions and to illuminate the darker area.  SIM card slot: It holds the subscriber identity module or SIM card.  Micro SD card: It holds the memory card of the smart phone. © 2018. DesignTech Systems | Confidential | All rights reserved.

5.  Antenna: It is a component inside a smart phone that receives and transmits signals for communication through voice and text messages.  Network section: It consists of antenna switch module IC, signals received by the antenna are given to the antenna switch module IC through the antenna socket and then further processing of signals is done.  Radio frequency (or) RF Transceiver IC: It is two way radio that combines the RF transmitter and RF receiver.  Intermediate frequency IC: It works as a receiver of audio waves.  Power management IC: It takes power from the battery and provide it to all other components of smart phone.  Audio codec IC: It controls speaker and microphone of a smart phone.  Near field communication (or) NFC controller: It accepts instructions from software and then processes these instructions for the completion of tasks. © 2018. DesignTech Systems | Confidential | All rights reserved.

6.  Rear facing camera: It also called as primary camera has a lens facing away from the user.  Front facing camera: It is also called as secondary camera has a lens facing the user on the same side of the screen.  Charging IC: It charges the battery by taking current from the charger.  Voltage regulator IC: It is designed to automatically maintain a constant voltage level.  Random access memory (or) RAM IC: The apps that are downloaded and installed are first loaded in the random access memory or RAM and then executed.  Read only memory (or) ROM IC: It is a data storage on a smart phone which stores preinstalled programs.  Multimode multiband RFIC: It is a power amplifier IC which is used to drive the antenna of a transmitter.  WI-FI module IC: It is responsible for all Wi-Fi networking functions and connects the smart phone to the internet

7. Chassis: It consists of vibrator motor this motor generates vibrations when a call is received. Flex cable (or) volume button: When volume button is pressed the springs on the flex cable of volume button are operated. Battery: It supplies voltage to all the IC’S and components on the motherboard and display assembly. Back cover: It is to protect the inner assembly of the smart phone. Home button: It is provided on the smart phone to go to the home screen. Display: The display assembly of a smartphone has active matrix organic light emitting diode or AMOLED technology and capacitive type touch screen. Recent APP’s soft key: It is provided on the smart phone to access the list of the recently opened app’s. Back soft key: It is provided on the smart phone to go back to the previous screen in all opened app’s and menus. © 2018. DesignTech Systems | Confidential | All rights reserved.

8. WORKING PRINCIPLE OF SMART PHONE  When a charger is connected to the smart phone charging port the supply is provided to the charging integrated circuit and battery connector’s.  Here the battery get’s charged through the charging IC and battery connectors on the motherboard.  The same battery connectors provides voltage to the power management IC.  The power management IC stabilizes the voltage as per the requirement then the stabilized voltage is supplied to the different assemblies such as display assembly, camera, audio jack, speaker, loud speaker, and daughter board components.  When ever home button or power button on the smart phone is pressed display assembly gets the voltage through the connectors on the motherboard.

9.  When a call is initiated the voice signals are processed through the audio codec IC thus IC converts the audio signals to digital signals.  Further this digital data is processed by RF transceiver IC and transmitted through the antenna on the motherboard.  Antenna converts the Electrical signals to the radio waves and vice-versa. © 2018. DesignTech Systems | Confidential | All rights reserved.

10. DISASSEMBLING A SMART PHONE  To disassemble the smart phone first power off the smart phone.  Then turn over the smart phone to remove the back cover.  Next insert the plastic opening tool in to the notch on the power button side of the smart phone and gently remove the back cover.  After that remove the battery using the same plastic opening tool from the bottom right corner of the battery and lift the battery up words and remove it from its slot.  Then pull the micro SD card from it’s slot and remove the card from the smart phone.  Similarly remove the SIM card and flip over the smart phone.  Now using the hot air gun heat the edges of the smart phone so that the adhesive is removed which is present at the frame of the display.  Then take a triangle opening tool and insert it in the joint where the display assembly is attached to the frame. © 2018. DesignTech Systems | Confidential | All rights reserved.

11.  Next slide the triangle opening tools around the edges of the display assembly further lift the display assembly away from the smart phone.  Then disconnect the connection of display assembly using fine tip curved tweezers and remove the display assembly from smart phone.  Next locate the screws that external mid frame after that using Phillips screwdriver remove the screw.  Similarly remove all the screws and turn over the phone and remove screw’s on the battery side of the mid frame and flip over the smart phone.  Now carefully separate the external mid frame and internal mid frame from each other.  Then locate the head phone jack next remove the head phone jack with the flex cable after that locate the ribbon cable of home button.  Then using the fine tipped curved tweezers remove the ribbon cable from home button. © 2018. DesignTech Systems | Confidential | All rights reserved.

14.  Next remove the home button assembly along with the ribbon cable from the display side.  Now remove the first screw that holds the mother board to the smart phone similarly remove the second screw.  After that locate the antenna and using fine tipped curved tweezers disconnect it and flip over smart phone.  Further lift the connectors for the buttons using fine tipped curved tweezers then separate the mother board of the smart phone from the chassis.  Then locate rear facing camera, front facing camera using plastic opening tool remove them from their locations.  Now locate daughter board then using the plastic opening tool release the connector and separate the daughter board assembly from the mother board assembly. © 2018. DesignTech Systems | Confidential | All rights reserved.

15. ASSEMBLING THE SMART PHONE  To assemble the smart phone first align and place the daughter board to the mother board of the smart phone.  Then gently press it down using fingertips as it has adhesive which sticks to the mother board.  Next place and connect the front facing camera to its location on the mother board.  Similarly place and connect the rear facing camera to its location on the mother board now flip over the mother board.  Then attach the mother board of the smart phone to the chassis after that push down the connectors.  Then place and attach antenna to the mother board.  Now place and tighten the first screw to the mother board similarly tighten the second screw.  Then place and align home button on the display side.  Next connect ribbon cable of home button on the battery side. © 2018. DesignTech Systems | Confidential | All rights reserved.

16.  After that by using tweezers align and connect the headphone jack along flex cable to the external mid frame of smart phone.  Then place the internal mid frame on the external mid frame.  After that attach the screws on the display side of the mid frame n battery side of the mid frame.  Next properly place and align the display assembly and by using fine tip curved tweezers attach the connector of the display assembly.  Further using fingertips properly fix the display assembly now insert SIM card in it’s slot.  Then place and align the battery in its slot and attach the back cover then flip over the smart phone and power ON it by pressing the power button.  In this way we need to assemble the smart phone. © 2018. DesignTech Systems | Confidential | All rights reserved.

17. SOFTWARE PROBLEMS OF SMART PHONE  Different software problems are like- Camera failed error, Smart phone hang, Touch screen unresponsive.  Software problem may be resolved by soft reset the smart phone.  Camera failed error: To troubleshoot this error.  TAP ON APP’S---Camera—if camera is not responding then tap on  Settings----Application manager------camera now tap on clear cache.  Then restart the phone and tap on camera, if it still not responding then power off the smart phone.  Press volume up button----- home button----- power button simultaneously for at least six seconds----recovery menu----volume down button-----select wipe cache partition----and confirm it by pressing power button.  Press the power button to confirm reboot and restart the smart phone.  If still problem not solved then. © 2018. DesignTech Systems | Confidential | All rights reserved.

18.  Press volume up button----- home button----- power button simultaneously for at least six seconds----recovery menu----volume down button-----select wipe data or factory reset----and confirm it by pressing power button---yes delete all user data---restart smart phone  If all those steps fail to resolve the camera failed error then check the hardware of camera.  Touch problem: To resolve this problem.  Power off smart phone---remove SD card----SIM card----reinsert after few seconds----power on smart phone.  If sill not working then perform soft reset---if still not resolve then perform factory reset as per standard procedure.  If sill not working then check hardware assembly. © 2018. DesignTech Systems | Confidential | All rights reserved.

19. HARDWARE FAULTS  Battery charging faults: In order to troubleshoot the battery charging faults we need to fallow the following procedure.  First check the charger of the smart phone if charger is faulty then replace it with new one.  Second check whether battery of the smart phone is working are not with the help of multi meter.  Set the multi meter to 20v and connect the probes to terminals of the battery if multimeter displays 3.85v then battery is in good working condition.  Now check the battery connectors on the smartphone main PCB.  If the multimeter displays greater than 700 ohms then battery terminals is in good condition.  Multimeter beeps if the connectors are short in such case replace the connectors on the motherboard. © 2018. DesignTech Systems | Confidential | All rights reserved.

20.  If still battery is not getting charged then check the charging port with multimeter if it displays greater than 500 ohms then charging port is in good working condition if not replace the charging port from the midframe with new one.  If still the battery is not charging then check charging IC.  Now check the area near charging IC for white residues which are formed if the PCB comes in contact with water.  Remove the white residues with isopropyl alcohol spraying it on lint free tissue.  If still not charging then replace the charging IC with new one. © 2018. DesignTech Systems | Confidential | All rights reserved.

22. NET WORK PROBLEM: The network problem may occur because of corrupted international mobile equipment identity or IMEI number. To check the corrupted IMEI number dial the code *#06# Then the IMEI number of the smart phone is displayed as null on the screen. To resolve this problem first dial *#*#3646633#*#* the smart phone displays Engineer mode. Then check the connectivity option and select the Radio information in CDS information. Now click the phone 1 option Then enter AT+EGMR=1,7,*IMEI number* and tap on SEND AT command. Now restart the device, if still no network check the network section of the smart phone. © 2018. DesignTech Systems | Confidential | All rights reserved.

23.  Network section of smart phone consists of --- Antenna switch, Antenna switch module IC, RF Transceiver IC, Intermediate frequency integrated circuit IFIC.  Network section in a smart phone is responsible for controlling the incoming and outgoing calls.  If there is a no signal or weak signal then there might be a problem in the antenna wire connected to antenna switch so properly connect the wire to the switch.  If still no network replace the antenna switch with new one.  If still no network check the PCB path from antenna switch to network section with multimeter with continuity mode if it does not beep that means the path is not in good working condition.  So add jumper wire on the path and check again if still problem not resolved then check the IC’S of the network section.  Connect the probes of the multimeter to first pin of IC and other to the ground point on the motherboard. © 2018. DesignTech Systems | Confidential | All rights reserved.

26.  If the multimeter displays the reading of 20 ohms hence the IC need to be replaced. If it displays greater than 500 ohms then the IC is in good working condition.  In this way we need to troubleshoot the network problem.  Over Heating Problem: The causes for the over heating problem  Using number of applications simultaneously.  Using mobile data for longer time and software up gradations.  Problem with power IC and flash IC.  The troubleshooting procedure for first two problems is  Press volume up button----- home button----- power button simultaneously for at least six seconds----recovery menu----volume down button-----select wipe data or factory reset----and confirm it by pressing power button---yes delete all user data-- -restart smart phone it is also known as formatting. © 2018. DesignTech Systems | Confidential | All rights reserved.

27.  If the problem still persist then update the software of the smart phone to latest version.  If the problem still exit then check the power IC and flash IC  Take multimeter and set it to 20v dc for the voltage of battery connector on the motherboard.  Connect positive and negative terminals of the multimeter to the motherboard.  If its shows the voltage reading of 2.0v it is because of over heating ideally the voltage should be 3.85v in this case replace the power IC.  Repeat the same if flash IC found faulty are over heating. © 2018. DesignTech Systems | Confidential | All rights reserved.

28. SOUND FAULTS  Ear speaker repair: If low voice or no voice is heard at the time of receiving a call then there is a problem with the ear speaker.  Some times low sound problem may happen if there is a problem in network.  To troubleshoot this problem first locate the ear speaker then take a multimeter and set it to continuity mode.  Connect the probes of the multimeter to terminals of the ear speaker if it display the reading of 45 ohms then the ear speaker is faulty if it beeps and shows the reading in between 16 to 32 ohms then ear speaker is in good working condition. © 2018. DesignTech Systems | Confidential | All rights reserved.

30.  Ringer or Loud speaker repair: Ringer problem arises if smart phone does not ring at the time of receiving call and low and weak sound is heard while playing music and videos.  To troubleshoot this problem power off the smart phone and disassemble as per the standard procedure and locate the ringer.  Take a multimeter and set it to continuity mode and connect the probes to the two ends of the ringer.  If the mutimeter displays 40 ohms then the ringer is faulty replace it with new one if it beeps and shows value between 8 to 10 ohms then the ringer is in good condition.  If still the problem is not solved then take multimeter and set it to 4k ohms and connect the probes to the terminals of the ringer.  If it displays the reading OL hence the terminals attached to the daughter board is faulty. if the resistance value is displayed 550 ohms then the ringer terminals are in good working condition in this case replace the daughter board with new one © 2018. DesignTech Systems | Confidential | All rights reserved.

32.  Micro phone repair: To troubleshoot this problem disassemble the smart phone as per the standard procedure.  Now take a multimeter and set it to continuity mode.  Then connect the probes of the multimeter to the terminals of the micro phone if it shows the value of 700 ohms then interchange the probes and if shows the reading of 900 ohms hear the multimeter shows the reading for both sides hence the micro phone is faulty condition replace it with new one.  If it displays resistance value between 600 to 1800 ohms for one side and it does not display any value for other side then the micro phone is in good working condition.  Further locate the micro phone and care fully remove it as per the standard procedure and replace with new one. © 2018. DesignTech Systems | Confidential | All rights reserved.

34.  Vibrator Repair: If the smart phone does not vibrate when a call is received then the vibrator might be faulty.  Vibrator motor of a smart phone works on 1.5v.  First check the points on the mother board where the vibrator is connected.  To check the vibrator insert fine tip curved tweezers under the flex cable of the vibrator and move it towards the vibrator motor and take away complete assembly of the vibrator motor and flex cable.  This vibrator is fixed with the adhesive to the chassis of the smart phone.  To check the points set the multimeter on 20v then connect the probes to the two terminals of the vibrator. If the display shows the reading of 1.5v then the mother board is in good working condition.  Now connect the battery test probes to the terminals of the vibrator motor if it does not vibrate then it is faulty replace it with new one. © 2018. DesignTech Systems | Confidential | All rights reserved.

36.  Audio jack problem: The audio jack problem arises if the head phone is plugged into the head phone jack and no sound is heard.  And no head phone is plugged in and still the head phone symbol is displayed on the screen.  This problem may arise if the smart phone comes in contact with water and points on the PCB board near head phone jack get shorted.  To troubleshoot this problem power off the smart phone then disassemble the smart phone as per standard procedure.  Then locate the audio integrated circuit or audio IC and using brush clean the audio IC and clean it with the isopropyl alcohol with lint free time and wipe the area.  Then using hot air gun apply some hot air and assemble the smart phone.  If still faces the same problem then replace the head phone jack with new one as per the standard procedure. © 2018. DesignTech Systems | Confidential | All rights reserved.

38.  If still problem is not solved then check the resistors near the audio IC with multimeter if it display the reading as open loop or OL then the resistor is faulty.  If it display a value like 20k ohms then the resistor is in good working condition.  If still the problem remains then replace the audio IC with new one.  Display problem: Display problem arises if the touch screen of the smart phone becomes unresponsive  To troubleshoot this problem disassemble the smartphone as per standard procedure and check the voltage supply of on board connector.  Then take a multimeter and set it to 4v then connect the probes to the first pin of the on board connectors and the ground point respectively if it shows the reading 3.85v then the mother board is in good working condition.  Then clean on board connector with isopropyl alcohol similarly clean the connectors of display assembly. © 2018. DesignTech Systems | Confidential | All rights reserved.

40.  If still problem is not resolve then replace the display assembly as per standard procedure.  Some times even though display assembly is good the connectors of display assembly does not get voltage supply from the mother board then check the voltage supply by using multimeter.  If the multimeter display 0v then the motherboard is faulty so replace the motherboard as per standard procedure.  Volume button not working: To troubleshoot this problem disassemble the smart phone as per the standard procedure.  Next locate the three springs which makes contact with the three small squares on the external mid frame and by using hand tool slightly push them down to check the working condition.  Further using finger tip properly align the springs if the problem still not solved then replace the flex cable of volume button. © 2018. DesignTech Systems | Confidential | All rights reserved.

42.  Power on (or) off button problem: To troubleshoot this problem disassemble the smart phone as per the standard procedure.  Then check the two springs on the mother board of the smart phone and align them properly if still not working replace the flex cable of power button. © 2018. DesignTech Systems | Confidential | All rights reserved.

43. THANK YOU © 2018. DesignTech Systems | Confidential | All rights reserved.43