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REPAIR AND
MAINTENANCE OF
MOBILE CELL
PHONES
Mobile Cell Phone ‘repair and
Maintenance
Introduction
Welcome to this course on mobile cell phone repair and maintenance. A mobile cell phone is a hand held mobile device that can perform several communication functions. Mobile technology has become one of the fastest growing technologies in the world. Today people use mobile phones to stay in touch with friends and family, to share stories and photographs in social media, and to carry out financial transactions. Indeed, according to a World Bank policy research paper of 2012, 93% of Kenyans owned a mobile phone by the end of 2011. This widespread ownership and use of mobile phones has created a need for professionals who can repair and service mobile phones. This course has been developed to address that need. The course targets
people who would like to start and run a mobile repair and servicing business. By the end of this course you should be able to disassemble and assemble a mobile phone, diagnose the problem, service and repair a mobile phone with the help of proper tools and instruments. This course is provided through distance learning and we trust that you will find the material useful both for studying and as future reference. We welcome your feedback on any issue relating to this course and wish you all the best. Happy Learning!
Learning Outcomes
Upon completion of this course you will be able to:
- Identify different types of mobile cell phones
- Recognise potential hazards in the repair of mobile cell phones
- Identify the parts of a mobile cell phone
- Use the correct hardware tools to repair mobile cell phones
- Assembly and disassembly a mobile cell phone
- Identify mobile cell phone faults and solve them. Topic 1: Types of Mobile Phones Before we discuss the types of mobile phones, let us first look at the meaning of a mobile phone.
What is a mobile phone?
A mobile phone is a handheld device that allows you to make and receive telephone calls while you move around a wide geographical area. A mobile phone also supports several other functions, such as text messaging, email and internet access, photography, money transfer, banking, and so on.
Types of Mobile Phones
There are many different types of mobile phones available in the market. Which ones do you know? Take 2 minutes to think about it and then complete the following activity. Well done! We believe your answer included the following types of mobile phones:
- Bar
- Brick
- Touch screen
- Flip
Figure 2: Touch screen phone The Touch screen Phone A touch screen, or slate phone is a subset of the bar form. Like the tablet computer, a touchscreen phone has minimal buttons and instead relies on an electronic visual display known as a touch screen. It also has an onscreen QWERTY keyboard. QWERTY refers to the arrangement of keys or buttons on an English computer keyboard. Figure 2 shows a picture of a touchscreen phone. The Flip Phone A flip or clamshell phone consists of two or more sections that are connected by hinges, HYPERLINK "http://en.wikipedia.org/wiki/Hinge" as shown in figure 3. The hinges allow the phone to flip open and fold to close in order to become more compact. When flipped open, the phone's speaker and microphone are placed closer to the operator's ear and mouth, thereby improving usability. Figure 3: A flip phone Figure 4: A slider phone
The Slider Phone A slider or slide phone is composed of usually two, but sometimes more, sections that slide past each other on rails. It usually has a display segment which houses the speaker and screen, while the segment that slides in and out contains the keypad or keyboard. The sliding form factor allows the owner to take advantage of a full key board without sacrificing portability. Figure 4 shows a picture of a slider phone. We hope you now understand the various types of mobile phones. Let us now look at the potential hazards that are associated the repair of a mobile phone. Topic 2: Potential Hazards Associated with Mobile Phone ‘epair Your physical well being is important not only to yourself, but also to others. Therefore, as you embark on mobile phone repair, you should be aware of all the potential hazards and how to prevent them.
What is a hazard?
A hazard is anything that has the potential to cause harm to yourself or those around you. Before you learn the different types of hazards, let’s start by defining some of the terms associated with hazards. Write down the meaning of the terms in the following activity. Term Meaning Flammable Corrosive
A mobile phone has several parts or components. It is important for you to know the parts and understand their functions so that you can easily diagnose and solve problems. How many parts of a mobile phone do you know? Take a minute to think about it and then complete the following activity. Part Function Flammable Corrosive Toxic Fumes A conventional mobile phone is made up of many parts. Table 2 below explains the functions of the main parts. Table 2: Parts of a mobile phone and their functions Parts of a mobile cell phone Functions Keypad Used for inputting or entering data into the phone. It is connected directly to the CPU Ear piece Converts the electric signal to a sound signal Mouth piece Transmits sound from one phone to another Battery Source of power supply to a mobile phone Power switch Switches the phone on and off Power IC It^ takes^ power^ from^ the^ battery^ and^ supplies^ to^ all other parts of a mobile phone Oscillator It creates frequency during outgoing calls Displays data. It is connected to the CPU to receive
Screen or display following signals : LCD Data Signal, LCD Reset Signal, LCD WR Signal, LCD RD Signal, LCD FLM Signal, LCD HSYN Signal etc. Flash IC Stores^ the^ software^ and^ other^ programs^ installed in the mobile phone Charging IC Takes the current from the charger and charges the battery CPU Controls all sections of a mobile phone Antenna Receives and transmit radio frequencies and helps the phone to connect to the cellular network Figure 5 below shows a printed circuit board (PCB) of a mobile phone showing the different internal parts. As you can see from this diagram the PCB is divided into two parts, the network section and the power section. The network section controls the incoming and outgoing phone calls, while the power section controls the memory and power related functions of the phone. Figure 5: Parts of a mobile phone We hope you now know the different parts of a mobile phone and their functions. Make sure that you learn them well and are be able to locate them easily before you move on to the next section. Let us now look at the tools that you need to repair mobile phones. Topic 4: Mobile Phone ‘epair Tools There are hundreds of tools for mobile phone repair available in the market. It is important to select the best tool that enables you to repair the phone easily and comfortably. Before you continue reading complete the following activity.
Factors to Consider When
Choosing Mobile Phone Repair
tools
When selecting tools and equipment for repairing mobile cell phones, you should consider the following factors:
Figure 7: PCB holder
- Solder Wire : used to solder electronic HYPERLINK "http://www.electronicsandyou.com/electronic-components-parts/electronic_c omponents_parts.html" components, ICs or jumpers. The composition of most solder wire is Tin / Lead in the ratio 60:40 or 63:37. Figure 8: Solder wire
- Thinner or PCB Cleaner: Thinner or PCB cleaner is used to clean the PCB of a mobile phone. The most common PCB cleaner used in mobile phone repairing is IPA or Isopropyl Alcohol. It is important to buy only good quality PCB cleaner as poor quality PCB cleaners can damage the system board. Figure 9: Thinner or PCB cleaner
- Jumper Wire: This is a thin laminated or coated copper wire used to jumper from one point to another on the track of a mobile phone during repair.
- Point Cutter : It is used for cutting Figure 10: Jumper wire Figure 11: Point cutter
- Blade Cutter : This is used to remove lamination from jumper wire. It can also be used for several other purposes. Figure 12: Blade cutter
- Nose Cutter : this is used for cutting. Figure 13: Nose Cutter
- Multi meter : an electronic measuring device that has the ability to measure voltage, current and resistance. It is used to test and check the readings of various parts and components of a mobile phone. Figure 17:Digital Multimeter (Source: commons.wikipedia.or g)
- Hot Air Blower : It is also called SMD (Surface Mount Device) rework system and SMD repair system. It has control to regulate or manage temperature and flow or hot air. Always buy a good quality ESD-Safe hot air blower. Figure 18: Hot air blower
- Battery Booster : It is used to boost the power of battery of a mobile phone. Figure 19: Battery booster
- Screwdriver Kit : It has several screwdrivers of different shapes and sizes to disassemble and assemble a mobile phone. Figure 20: Assorted screwdrivers
- Microscope : It is used to see a magnified view of PCB or electronic components. These are available in different zoom options. Many microscopes can also be connected to a computer or a monitor. Figure 21: Microscope
- Test JIG Box : This device is used to diagnose and find fault or problem in a mobile phone. It helps the mobile phone to work and function normally outside its case. This helps to test and check voltage and other test points on the PCB. In simple words it helps the mobile phone to work without battery.
Figure 25: Solder paste
- LCD Tester : Used to check whether the LCD screen of a mobile phone is faulty or not. Figure 26: LCD tester You now know the main tools that are used to repair a mobile phone. In the next topic we shall discuss how to disassemble and assemble a mobile phone. Topic 5: Disassembling and Assembling a Mobile Cell Phone
What is to disassemble?
To disassemble is to take something apart or to break it down into pieces.
What is to assemble?
To assemble is to fit together all the separate pieces in order to form one whole. Before you continue reading, complete the following activity.
Disassembling a Mobile Phone
The following are the steps that you should take when disassembling a mobile phone:
- Switch off the phone
- Remove the battery cover
- Remove the battery, SIM card memory card (if any)
- Remove all the screws from the phone
- Lift back the cover with the help of a flat screwdriver
- Remove the strips (buzzer strip, display, camera, volume and speaker button strips)
- Remove the antennae wire from the outside
- Remove the motherboard and vibrator. To successfully disassemble a phone, you need to understand the various internal sections of a mobile phone and how they are connected to the CPU. Let us look at that next.
Internal Parts of a Mobile Phone
Table 3 below outlines the main sections and how they are connected. Table 3: Internal parts of a mobile phone Internal Section Connections SIM card section SIM Card Interface section is directly connected with the CPU in most mobile cell phones. If there is no power supply in a mobile phone then the SIM section is connected with the CPU through the Power IC. Memory card section In most phones the micro SD card holder is connected through a 8-pin socket. The memory card section is found inside the CPU
FM Radio Section FM Radio Driver IC, FM Antenna, Signal and Supply Components are made in the FM Radio Section. Bluetooth Section Bluetooth Antenna, Bluetooth RF Signal Filter, Bluetooth Driver IC, Supply and Signal Components are found in this section. The Bluetooth section functions like the Network Section. The RF-CLK signal is given to the Bluetooth driver IC during signal processing. Hands free (Earphone) Section: The hands free jack, hands free MIC, speaker signal component and hands free audio amplifier are present in this section. Hands free symbol is displayed after connecting the Hands free jack.
Assembling a Mobile Phone
The following are the steps that you should take when assembling a mobile phone:
- Fix the vibrator strips of speaker and volume button
- Fix the motherboard
- Connect the antenna with wire
- Place the camera and connect it
- Place the buzzer
- Put the camera cover
- Make sure that the LCD is working before you place the screen
- Put battery and battery cover So far you have learnt about the hazards of mobile phone repair, the parts of a mobile phone, the tools to use and how to assemble and disassemble a mobile phone. Now let us look at how to diagnose and repair a mobile phone. Topic 6: Diagnosing and ‘epairing Mobile Phone Faults The correct diagnosis of mobile cell phone faults is the key to successful and cost effective repair of the phone. Let us start by looking at the skills that you need to have to be able to diagnose and repair a mobile phone.
Skills Needed to Diagnose and Repair
a Mobile Phone
Before you can diagnose and repair a phone, there are some skills that you need to learn. These skills are:
- Soldering
- Desoldering
- Testing using a multimeter
- Jumper setting Let us briefly discuss each skill in turn.
Soldering
Soldering is a process in which two or more metal items are joined together by melting and flowing a filler metal into the joint. The filler metal has a relatively lower melting point. Figure 27: Picture showing A technician Soldering Steps In Soldering
- Prepare the following materials:
- Soldering Iron,
- Solder paste
- Long Nose Pliers,
- PCB holder,
- Electronic Components (Resistors, Diode etc.)
- Plug and pre-heat the soldering iron.
- Heat both items at the same time by applying the soldering iron to the copper pad and the component lead.
- Continue heating and apply a few millimeters of solder. Remove the iron and allow the solder joint to cool naturally.
- It only takes a second or two to make the perfect joint, which should appear shiny.
Desoldering
Desoldering is the removal of solder and components from a printed circuit board for troubleshooting, repair, replacement, and salvage. Figure 28: Desoldering Steps in desoldering
- Use a solder wick (finely braided copper) to wick away excess
