Mobile Basic Book

7/27/2019 Mobile Basic Book

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Mobile Basic

Basic Electricity

Electricity is motion of electrons in certain materials. When electrons (containing “ – “charge)starta moving towards protons (containing “ + “ charge) this motion causes flow of numerous electrons. This flow is called electricity.

Basically the force that forces eletrons to flow is measured in “Volts” whereas the

quantity of electrons flown in certain time is measured in “Ampere’s”

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Formation Of ElectricityThere are two types of electricity according to its form

1. AC (Alternating Current)

2. DC (Direct Current)

1. AC (Alternating Current)



Alternating current is the type of current in which both current flow lines bear both type

of charge “+” and “ – “

In AC both lines contain “+” charge for a certain time and “ – “ afterwards

so it forms a wave in which the supper level from “0 level” is “+” and lower

level from “0 level” is “ – “. See figure 1.0

Sources of AC:

Commonly AC is supplied in Mains supply used in commen home electricalappliances. It is produced by “Dynmo’s” , “Turbines” and “Generators” and also in

“UPS” normally proveded AC in homes is measured 220 Volts and its Frequence(cycling

speed of “+” and “ – “ charge) would be 60 Hz(hertz frequency measurment units). And

in some countries it would be 110 Volts and 50 Hz.

2. DC (Direct Current)

Direct Current is derrived from its shape. The charactristic of DC are

1. DC is not in wave form rather it is straight

2. DC contains “+” charge on one line and “ – “ charge on another line( See

Figure 2.0



Sources:

Normally sources of Direct Current are batteries, Cells, Solar Cells and DC

Adapters and Chargers.

AC To DC Conversion“AC” can be changed into DC as well as DC into AC. While converting AC into

DC we need a few components calles detectors commonly known as Rectifire Diods. The

complete function of Diods is discussed in “ Parts Detail and Function Lesson”, but here Iwant show the simple process in which “AC” is converted into “DC”. First of all we

should know the main differences between AC and DC.

1. “AC” contains “+” and “ – “ cahrge in wave form whereas “DC”

contains “+” and “ – “ charge in straight shape.

2. “AC” contains both “+” and “ – “ charge on both lines whereas “DC”contains “+” charge on one line and “ – “ charge on another line.

So it is easy to convert “AC into “DC” by straightening charge shape and by

making it seperate.



Note: this circit with some modifications is used in mobile phone chargers.

Cell Phone System

hi dear students, in the first place of your course i would like to introduce you about cell phonebasics and the very basic techniques with the cell phone works. while beginning to the maintechnology of cell phones you should know about the basic sections of a mobile phone. Aconventional mobile phone contains three main sections prescribed as under.

• Radio Section Power section• Computer section

Radio section

A radio section is based on two main Circuits.

• Transmitter

• Reciever

A simple mobile phone uses these two circuits to correspond to an other mobile phone.A Transmitter is a circuit or device which is used to transmit radio signals in the air.and areciever is simply like radios which are used to recieve transmissions(Radiation) which isspread in the air by any transmitter on a specific frequency.



The two way communication is made possible by setting two transmitters and two recieverssycronized in this form that a trasmitter in a cell phone is syncronised with the frequency of other cell phone's recieving frequency same like the transmitter of second cell phone issyncronised with the recieving frequency of first cell phone. So first cell phone transmits itsradiation in the air while the other phone listens it and same process is present in the oppositside. so these hand held two cell phones correspond to one another.

the technology used in these days is a little bit different but it is based on the basic theoryprescribed before. the today's technology will be discussed in later on.Power Section. A powersection in mobile phones is designed to handle energy matters that is cosumed in mobilephones.There are two main sub sections in a single power section.

• Power Distribution and switching section

• Charging Section

A power distribution section is designed to distribute electricity to the othersections of a phone. this section takes power from a battery (which is figured

commonly 3.6 Volts)and in some places it is steped down to various volts like 2.8 V1.8V 1.6V etc.while on other place it also steps up the voltage like 4.8 V. this sectionis commonly designed around a power IC(and integrated circuit) which is used todistribut and regulate the voltage used in other components.

The Charging section is based on a charging IC which takes power from anexternal source and gives it to battery to make it again power up when it isexausted.this section uses conventiolly 6.4 V from an external battery charger andregulates it to 5.8V wile giving it to battery. The battery is made charged by thisprocess and it is ready to use for the next session(a battery session is a time which isprovided by the maufactrur of a cell phone for standy by condition of a mobile phoneor talk condition.)

Computer Section

a computer section is used in mobile phones to handle decision makingapplications like making decision the phone should be power on when its powerswitch is pressed down one time and on the other time the phone should be poweredoff. this section is commonly based on around three main components

• RAM( Random Access Memory) ROM,Flash(Read Only Memory

• CPU( Centeral Processing Unit)

The very first part is a memory component which commonly saves in it self user definedsetting of a phone and contacts Numbers. the informations in this memory chip is editable byuser easilyThe second Component contains mobile phone's operating system which is noteditable bye user but it is only in special conditionsThe Third Compnent is as like a simplebrain used to understand differnet situations ad to make decisions and to hold control on othercomponents as well as sections

Note: The special terms used in this lesson should be asked for if not understoodable



Introduction to Mobile Phone Part I

Dear Students Here are we going to study about different parts used in mobile phones andthere functions in the cell phone systems. To avoid non applicable items in mobile phones we

will discuss only key components which are responsible for the faults.

Resistance:

resistance mean a component which perform resistive effect while passing current throughthem. It is used to limit the current. The resistance also performs high resistance for highfrequency signals and low resistance for low frequency signals. Resistance is measured in “Ohms"

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Symbol Used For

Resistance In Schematics

or

Original Shape in general electronics

Shape used In Mobile Phones

To read the valus of resistance in general electronics there are fixed color codes to read

we read color codes from the left side. We assume first two color lines from the left as anumber and the third one is replaced with number “0” according to third line number

Example:

so the total value will be 10000 Ohms



Capacitor:

Capasitors or condensors are such components that charges the current in their self and also

filters the current for ripples in converted AC to DC Current. There are two main types of capacitors

used in mobile phones the first one is “Non Polar” and the second one is “Bipolar”. Non-polar

capacitors are normally for low capacitance whereas Bi-polar capacitors are normally high capacitance.

Capacitance is measred in “Ferad’s”and represented in schematics with the symbol of “µf (micro

ferad)”

Symbole Used in Schematics Non-Polar

Shape Used in general Electronics (Non-Polar)

Shape Used in Mobile Phones

Symbole Used in Schematics Bi-Polar

Shape Used in general Electronics (Bi-Polar)

Shape Used in Mobile Phones (Bi-Polar)

Coil:

A coil is a piece of metel wire( normally it is of copper) this is used tofilter low frequency signals because it performs low resistance for low frequency signals

but very high resistance for high frequency signals. A coil resambles to resistance by its

characteristics but there is a little difference between coil and resistance that coil resistsonly AC type of current DC is passed Directly whereas resistance resists DC as well as

AC.

Shape used in Schematics



Shape used in General Electronics

Shape used in mobile phones

Comparision

Resistance Coil

Capacitor

• Resists in the path of

current where it is

coupled

• Resists for both AC

and DC.

• Resists high for high

frequency and low for

low frequency

• Resists in the path of

current where it is

coupled

• Resists for only AC

• Resists high for high

frequency and low for

low frequency

• Charges the current

in itself.

• Dont let to pass DConly AC can passed from

• Performs high

resistance for low

frequency and low

resistance for high

frequenct

Introduction to Mobile Phone Part II

Dear friends here we will discuss about what kind of functions a typical mobile phone has solet us start our new lesson. while starting i would like to say all of you that you please keep intouch with me by our contact us page and please don't feel any hesitation to ask me any

question if you have about these lessons. these lessons will make you learn good repairingskills so keep reading these lectures.

First of all we will discuss how many main functions a mobile phone often has irrespectively of mobile brands.

There are three major sections inside a mobile phone

• Power Section

• Radio Section

• Computer Section

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Power Section:

A power section deals with power related tasks such as power distribution or charging thebattery so this section can be divided into two sub sections like.

Power Distribution

A power distribution section is built around an "power IC" it takes 3.6V power from batteryand regulates its power and then distributes to the other components used in mobile phonecircuit. in some mobile phones tech "RF Power amplifier" uses more Power than provided byemobile phone's battery .i.e. 4.7 V or 5.6 V in some phones. the power Ic with a power boastercoil is used to increase voltages. so we can say that power IC is used to provide power toother components how much they needed. either less than battery voltage or more than it.

Charging Section

A charging section works for battery charging purposes.it is often consists a fuse, a coil, a

protecting diode, a filter capacitor and charging IC and some other discreet. the chargingsection helps battery to be charged when it needs and when battery is charged, charging ICreads its state of charge and feels it full charged and then disconnects charging from it.

Radio Section:

A radio section has basically a set of four main functions.wich are.

• Band Switching

• RF Power Amplification

• Transmitter

• Receiver

Band Switching:

In the modern mobile phone communication techniques. the frequency of mobile phonecommunication is divided into three bands

• GSM (operates on 900 MHz)

• DCS (operates on 1800 MHz)

• PCS (operates on 1900 MHz)

the third band is used only in USA whereas the first two bands are used in the rest of theworld. band switching is done bye a "ceramic antenna switch" it reads from the radiationdispersed in the air and then switches to the appropriate band.

in the very first phase of mobile phones there were single band handsets which operated onsingle frequency band but now a days all the handsets are dual band or tri band in operation.

RF Power Amplifier



RF power amplifier is often called as ".PA" or"Transmitter" its functions is to amplify orboast the power which is being transmitted to air, so may it would be able to communicatewith long distances. a typical .PA can amplify rf power up to 0.6W or 600mW. This amount of rf power is sufficient to communicate nearly 20 to 25 kilometers in open area, but all the PA'sare controlled by there rf signal processor, so if we are near our cell base tower the PA of ourphone will transmit low power but if we are far away it will produce its maximum power.

Transmitting

A mobile phone's rf section is basically built around an rf IC which is often called rf signalprocessor whereas in nokia it is called hagar IC in some hand sets and in some hand sets it iscalled Mjoelner. irrespectively of the brands and verity of names we call it rf signal processor.this IC works as transmitter and receiver as well. working as transmitter it takes instructionsfrom phone's computer and also takes audio data from audio section and creates radio wavesthen mixes audio data to its radio waves according to the instructions given by computersection. this mixer of audio and radio is sent to PA to amplify its strength

Reciever

A reciver section for rf waves is built in rf IC, as it is said that this IC works for dual purposesfirst transmitting and section recieving. in the recieving section of mobile phones a radio signalis gather from ceramic antenna switch and then it is filtered and sent to rf IC to furtherprocess. in rf IC signal is detected and then rectified for audio and data which is sent to audioIC or computer section.

Computer Section:

A computer section in mobile phone consists of two main functions

• CPU(central processing unit)

• Memory (RAM, FLASH, COMBO CHIP)

CPU:

A CPU is used in mobile phones as a central processing arithematic or controler. the cpu

controls various functions in mobile phones like signal, display, sound converting(DSP),charging, power on, rf channel controler, rf tx power conroller, LEDs, vibrator, dataprocessing, data storing etc. so we can say that if a cpu is damaged in any mobile phone itcannot be repaired unless the CPU is not replaced but this type of fault is not even seen to meever either memory chips can be damaged. in brand Nokia CPU is named with two differentwords (MAD or UPP)

Memory:there are two main types of memories used in mobile phones

• RAM (Random Access Memory)

The RAM is used in mobile phones to store user data in mobile phones. So these a dayswe can store pictures, messages, ringtones, applications, themes and other these type of

things in mobile phones so CPU stores these types of data in the RAM of our mobile phones.



• Flash (eeprom, ROM etc)

The flash chip is used in mobile phones to hold mobile phone's operating system in it. so if the flash chip is damaged in mobile phones the phone cannot power on properly because allthe instructions to start a mobile phones and its various tasks like call making , display etc arestored in the flash chip of mobile phones.

• Combo Chip

In smoe mobile phones there is a combined type of memory used which is called combomemory chips these types of memories work for both like RAM and Flash.The clear example of this type of memory is used in Nokia 1100.

Note: Multy Media Cards are not a part of mobile phones becaues they are used externally.

Mobile Phone Function

Dear friends here we will discuss about what kind of functions a typical mobile phone has solet us start our new lesson. while starting i would like to say all of you that you please keep in

touch with me by our contact us page and please don't feel any hesitation to ask me any


First of all we will discuss how many main functions a mobile phone often has irrespectively of mobile brands.

There are three major sections inside a mobile phone

• Power Section

• Radio Section

• Computer Section

Power Section:

A power section deals with power related tasks such as power distribution or charging thebattery so this section can be divided into two sub sections like.

Power Distribution

A power distribution section is built around an "power IC" it takes 3.6V power from batteryand regulates its power and then distributes to the other components used in mobile phonecircuit. in some mobile phones tech "RF Power amplifier" uses more Power than provided byemobile phone's battery .i.e. 4.7 V or 5.6 V in some phones. the power Ic with a power boaster







called Mjoelner. irrespectively of the brands and verity of names we call it rf signal processor.this IC works as transmitter and receiver as well. working as transmitter it takes instructionsfrom phone's computer and also takes audio data from audio section and creates radio wavesthen mixes audio data to its radio waves according to the instructions given by computersection. this mixer of audio and radio is sent to PA to amplify its strength

Reciever

A reciver section for rf waves is built in rf IC, as it is said that this IC works for dual purposesfirst transmitting and section recieving. in the recieving section of mobile phones a radio signalis gather from ceramic antenna switch and then it is filtered and sent to rf IC to furtherprocess. in rf IC signal is detected and then rectified for audio and data which is sent to audioIC or computer section.

Computer Section:

A computer section in mobile phone consists of two main functions

• CPU(central processing unit)

• Memory (RAM, FLASH, COMBO CHIP)

CPU:

A CPU is used in mobile phones as a central processing arithematic or controler. the cpucontrols various functions in mobile phones like signal, display, sound converting(DSP),charging, power on, rf channel controler, rf tx power conroller, LEDs, vibrator, dataprocessing, data storing etc. so we can say that if a cpu is damaged in any mobile phone itcannot be repaired unless the CPU is not replaced but this type of fault is not even seen to meever either memory chips can be damaged. in brand Nokia CPU is named with two differentwords (MAD or UPP)

Memory:

there are two main types of memories used in mobile phones

• RAM (Random Access Memory)

The RAM is used in mobile phones to store user data in mobile phones. So these a dayswe can store pictures, messages, ringtones, applications, themes and other these type of

things in mobile phones so CPU stores these types of data in the RAM of our mobile phones.

• Flash (eeprom, ROM etc)

The flash chip is used in mobile phones to hold mobile phone's operating system in it. so if the flash chip is damaged in mobile phones the phone cannot power on properly because allthe instructions to start a mobile phones and its various tasks like call making , display etc arestored in the flash chip of mobile phones.

• Combo Chip



In smoe mobile phones there is a combined type of memory used which is called combomemory chips these types of memories work for both like RAM and Flash.The clear example of this type of memory is used in Nokia 1100.

Note: Multy Media Cards are not a part of mobile phones because they are used externally.

Mother Board System

This Lesson is intended to make you aware of the Fundamentals of a mobile phone's motherboard and I want to teach you about what a typical mother board.

A typical mother board is constructed using two main things

Fiber Plate

Copper Plate

These two plates are joined in three forms.

Single layer board

Double layer board

Three or tripple layer board

A single layer board is constructed yusing one copper plate and the other fiber plate. Its oneside is copper faced and other is fiber faced.

while a Double layer board is made with two copper sheets ad fiber sheet.Its one side iscopper faced and the other is also copper faced and the fiber is stcked between two coppersheets.this kind of board holds electronic components on both of its side because both coppersided prints anre inter connected with one another on proper places

A three layer board is made with three copper sheets and two fiber sheet.as it is shown below.

Basics about Mother Boards

Different mother boards have different views but many things are common in different brand

mother boards.first common thing is ,every mother board has radio Section(Discussed inLesson 1) on top of the mother board





On a conventional cell phone mother board there diffeent kinds of motherboards, some are thick and some are thin enough to see easily.The thick andthin tracks transfer current and data to from one part of the mother board toanother.the thick track passes hugfe amount of current in it so it is a very lowrisk that these tracks will burn up.

A sepecial track which is very thick and makes portions on a single board iscalled portion track.it is located on the above picture. This track is makingdifferent sections apart.

Frequency

Dear friends here we will discuss about what kind of functions a typical mobile phone has so

let us start our new lesson. while starting i would like to say all of you that you please keep intouch with me by our contact us page and please don't feel any hesitation to ask me any


What is frequency? and what are mobile frequencies?

Mobile phone uses radio waves to communicate with other mobile phones and when youare face to face with radio waves you ve to learn about frequencies.

The word frequency is derived from the word frequently which is used with the meaning of

circulation of any task repeated with same time period. so if any task is repeated with a sametime period you can call its ratio as frequency. In radio waves a the speed of waves going upand down is called frequency and it is measred in Hz(Hertz). if a wave finishes its ten cycles ina second its frequency will be 10 Hz. look at the cahrt below to learn more about thefrequencies.

1 cycle/second = 1Hz

1000 Hz =1Kilo Hertz (1Khz)

1000Khz =1 Mega Hertz (1Mhz)

1000Mhz =1 Giga Hertz (1Ghz)

1000Ghz = 1 Tera hertz (1Thz)





Frecuencies used in Mobile phones

there are three types of frequency bands used in mobile phones

• GSM 900 Mhz

• DCS 1800 Mhz

• PCS 1900 Mhz

some mobile phones are used to operate on single band but most of the new comminghandsets are dual bands which can operate on both GSM or DCS. But some of the very newtypes of mobile phones can operat on tri band GSM, DCS or PCS

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How Mobile Phone Power On

Dear friends here we will discuss about what kind of functions a typical mobile phone has whilepowering on so let us start our new lesson. while starting i would like to say all of you that youplease keep in touch with me by our contact us page and please don't feel any hesitation to

ask me any question if you have about these lessons. these lessons will make you learn goodrepairing skills so keep reading these lectures.

First of all look at the picture below carefuly. this picture describe booting detail about nokiamobile phones but same structure can be applied to the other brands with a little modification.






In the picture above all of you can see a little block diagram illustrating mobile phone bootingsequence. first of all I am starting explanation from power switch.

When apwer switch is pressed it turns on a ciruit inside the power IC and this IC startsdistributing power suplly to other parts of mobile phones. On the first place VCO( voltagecontrolled ocsilator) or an other type of clock ocsilator starts producing a clock frequencey of 26MHz in some mobile phones this clock frequency is directly used to run CPU but most of thesets in nokia brands it is distributed bye hagar IC or RF Signal processor and it becomes13MHz in the end of the division process. this low frequency cloack signal is used to start CPUfunctions now CPU which is like the brain of the mobile phone comes to the senses and first of all contacts its memory to know what are the instructions written it for this event and itsmemory tells CPU that if you feel that you are finding 13 MHz from hagar IC you have to run abooting test. in this test CPU tests most of the mobile phones function if they are correct CPUwill order power IC to continue providing power to other parts and CPU also starts its displaysection. so this is the total process in which a mobile phone comes to the power on state.

Responsible parts for mobile phone power failure

there are eight elements which can affect mobile phone power on function

• Power Swicth

• Battery

• Battery terminal

• power supply tracks

• power IC

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• Ocsilator (VCO)

• hagar IC

• flash (programming)

So we can say that when ever a mobile phone fails to power on there may be a fault in suchtype of parts which are used in mobile phone booting process

Common Faults

Dear friends here we will discuss about what kind of functions a typical mobile phone has solet us start our new lesson. while starting i would like to say all of you that you please keep intouch with me by our contact us page and please don't feel any hesitation to ask me any


First of all we will discuss how many main functions a mobile phone often has irrespectively of

mobile brands.

A typical mobile phone has various types of faults which can be distributed in two main kindsof faults

• Hardware faults

• Software faults

• Setting Faults

Hardware Faults:

Hardware faults in mobile phones are related to mother boards of mobile phone, batteriesand any physical fault will be amount to hardware faults. I have pointed out as much hardwarefaults as much i remeber this time but if you have a fault which is not listed below you can tellme by clicking here I willo be glad to know that it would be a great help for me too.The list of

common hardwarefaults is given below.

• dead set condition

• no charging

• battery empty

• auto charging

• low signal

• No signal

• voice problem

• vibrator problem

• ringer problem

• backlight problem

• auto turn off

• hanging problem


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• insert sim (no sim card inserted shows on the screen)

• keypad problem

• display problem

Software faults

• no signal

• dead set

• display

• contact service (contact retailer, contact service provider)

• Test mode

• not charging

Setting problem:

• call divert

• sim lock

• security code

• country lock

• cnfiguration of SMS

• configuration of GPRS

• configuration of call

all these faults described over this text are common found and i will try my best to describe alltypes of repairing available for such faults in the next lessons. I am working for this site andmy team is also working for the upgradation of this site so all of you can help us by if youknow something you can go to our forum at GSM Help Discussion and post lessons for others

to help us teaching all the people in the world so let us start registration at GSM Helpdiscussion and start posting new threads.

Keep in touch with us and soon you will find detail of all the faults described above stepby step you can oblidge your friends by telling us about our site helping suffered people inGSM Problems

Battery Problem

We are going to discuss here some techniques and steps to repair dead condition in mobile

phones irrespectively of brands

there are manay types of batteries used in mobile phones but now a days the mostpopular battery is "Lithium neon battery". as i have discussed in the first lesson aboutthe pins of mobile phone batteries there are two two types of battereis.

Note: in Sony ericson there are five pins used for battery terminal but dont beconfused first 2pins works togather third works alone and the last 2 pins also worktogather so you can take ir as three pin battery.

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• three pin battery

• four pin battery

Positive pin:

positive pin of mobile phone gives " + " type current which has normally 3.6V potentionaldifference with " _ " pin. a normal mobile phone battery now a days holds 3.6V when it is fullcharged it is normally 3.8V and when it is discharged it is normally at 3.2V.

Negative pin:A negative pin in mobile phone is simple as working in other types of batteries so there is noneed to discuss it more.

BSI pin:

BSI pin stands for "battery state indicator" this is a pin which tells the mobile phone's CPU thatwhat is the current state of battery is right now. in some mobile phones where three pin



battery is used, this pin also works to tell the mobile phone that what is battery tempratureright now.

B Temp:

B temp pin is specially designed to tell the mobile phone about battery temprature so some

mobile phone shuts down if their battery is heating up much while using. but this pin is now adays emerged in BSI pin so now a days most of the mobile phones use three pin batteryinstead of four pin battery.

Common faults caused by battery:

there are many types of faults created by batter and you will be amazed by looking that what

type of faults are our batteries creating.

• Insert sim card fault

• power on fault

• signal fault

• auto shut off while calling• battery empty fault

• test mode fault

Insert sim card fault:

It came to my experience that in nokia models where three pin battery and for powerpurposes UEM IC is used we can test that if BSI pin is not connected there will be a Insert simcard problem. for ex: if you disconnect only BSI pin in nokia 1100 or 2300 or 3100 there willbe a message for you on the screen "insert sim card"

Power on fault:

if you battery is not working it will not be able to supply proper voltage to your mobile phoneand it will not turn on so it creates power on faults.

Signal problem:

some times in some mobile phones the battery is so low but phone is running but there will beno signal in this situation but this problem was found only in old mobile phones sets and it isvery rare.

Auto shut off while calling:

some time we call some one while holding full signal in our mobile phone battery indicatorbars but as we call someone all battery signal drops and our phone shuts off it self.

Test mode fault:

there is a fault in some nokia mobile phones that they show " Test mode " while truningon. some time it is the fault of battery and some time it is a software problem







Not charging:

in this fault a mobile phone shows a message "Not charging" on the screen when ever itis connected with charging pins. this type of fault is not a mere hardware fault it is 90%software fault. this fault is present only in nokia and I personally experienced a problem with anokia 3100 it was showing "Not charging" i tried hardware solutions but totally in vain so I

upgraded my software now every thing was ok. . and this is the same case in many types of nokia brands you can check this up.

Only nokia 1100 when "Not charging" fault comes it is very hard to remove this fault in nokia1100 I only repaired a little number of nokia 1100 displaying this message there was aproblem in charge connector diode next to charging fuse. but often it can be solved by

repairing software or upgrading it.

Auto Charging:

In auto charging a phone continues showing charging despite of removing charging pin fromphone.

• in this type of fault the "BSI" pin of mobile phone is very important because it

is used to tell the phone what is the state of mobile phone charging now so if this pin is notok this fault occurs.

• there are some cases in wich a mobile phone battery is ok but auto charging is

present you can check transistors if used in charging section and if faulty replace it because

this transistor is used in some mobilephones to cut off charging from phone automatically. in• In some cases a resistance in charging section is responsible for that which is marked

as "R22" in charging section so you can check "+" supply connection with this





Dead Set

We are going to discuss here some techniques and steps to repair dead condition in mobilephones irrespectively of brands

First of all let us now about the main functions to power on a mobile phone you can

consult our previous lesson

Key Components and funtions:

Battery Power Switch battery terminal Power IC Oscilator Frequency divider CPU Flash (ROM / EEPROM)

.

Battery:

A battery is used to provide power supply to our mother board unit so if this battery or on of its funtions fails the whole mobile phone fails to power on. So battery must be in goodcondition to make a mobile phone power on. Some times the third Pin used in battery which iscalled "BSI" is not working correctly but voltage can be found in " + " and " - " terminals, inthis situation mobile phone cannot turn on.

Power Switch:

A power switch is used in a mobile phone to turn on and off mobile phones if it is faulty thewhole unit cannot power on so keep checking its terminals wether they are connected with thepower IC of not if not then you can make a jumpwer and connect it.

Battery terminal:

battery terminals connect battery to mobile phone component unit if its points are drysoldered of unsoldered or bended then you can change and fix this problem which is alwwaysin the result of no power on. so if battery terminals are working correctly you need to proceedfurther.

Power IC:

A power IC distributes current among all the components actually a power IC works as "voltage regulator" and " power on funtion" so if a power on funtion is faulty the whole unit willnot power on. but there are some problems with ICs that we cannot check them wether theyare working right or not rather we can only assume that they are faulty if the other functionsare correct.



Oscilator:

An oscilator makes low frequency which is called clock frequency. this frequency is used to rundigital components if this frequency is not available digital components fail to work and theresult is power on failure. the out put frequency is used in mobile phone's CPU and Memorychips and UEM Ic if used.

Frequency divider:

Frequency dividing is a funtion which is used in mobile phones to divide clocke frequency toget accurate frequency to run digital components so if divider is failed power on fault matoccur. this frequency dividing funtion is built in radio ICs commonly like hagar IC or Mojoelnerin Nokia mobile phones.

CPU

A CPU (central processing unit) is like a brain in mobile phones which controls the major partsof mobile phones so its funtionality is very necessory in mobile phones while testing in boot

process but its functionality is assosiated with Memory chips used in mobile phone speciallyFlash chip.

Flash Chip ( EEPROM)

A flash chip holds booting information in it self it has instructions stored in itself for the CPU tocontrol other components so if flash chip or its software is damaged it mean the set do notpower on. in case of damaged software the phone should be treated in flashing process

* The word flashing denotes in mobile phones that some software installation.

Steps to Repair Dead Set



Note Some steps which cannot be take in an average mobile phone lab are avoided to beexplained becaues oscilator and divider's functionality can be cehecked by Osciloscope which isnot available in an common mobile phone lab.

Ringer Problem



Ringer Problem is also same in all brands of handsets, here we will discuss components whichtake part in creating Ringer problem in mobile phones. first of all we should know about keyelements used in making in mobile phones. these components are listed below.

• Ringer• Tracks

• Ringer Controller IC

• Programming

Ringer:

A ringer is commonly taken as a speaker, in the former sets we found ringers like two metalplates joined together. one plate was small and the other was large and there was a crystalmaterial between the two plates so there was a capacitance effect between the two plates.and when the supply was connected to the ringer given below it would give a sound like"Click" but if it was connected with AC supply it would give voice like "Shar r r r r r r r r r r r !"

and so on.

In the old ringer models there was an oscillator used to make different voice frequencies inringer . so they made it to produce different tunes procured by CPU and its memory and voiceoscillator.

These days most of the ringers are behaving like an ear piece used in mobile phones. it wouldbe right to say that now a days ringer and speakers are merged in the same shape altogetherand instead of using an other piece working as ringer the Companies use a speaker which isworking as speaker as well as ringer. please read below carefully.

. most of the old nokia , samsung and motorola phones were built with a ringer and speaker

2. Now a days nokia , samsung and motorola are using speakers as earpiece and ringerpurposes .because the speakers are used to make a ring

3. Sony Ericson use mostly a piece in which there are four points two for ringer and two forear piece because they have made both things in joined form.

4. another difference is that in all the mono ringtones hand sets there was a separate ringerand a separate speaker used.

Checking Of Ringer:

If you suspect that a Ringer is damaged you can check it as the following ways.



• Check if its points ar not broken if it is so you can replace this Ringer on the basis of

its shape and size because now a days all the vibrators are operate on same voltages buttheir shape and size is different.

• Check continuity between the two terminals of Ringer if there is no continuity then

consider this vibrator damaged and replace it. (because now days speakers are used asringer and ear piece altogether and speakers have full continuity between the two terminals).

Tracks:

In the ringer problem there may be certain chances that the tracks may be broken and if it isso then trace the tracks leading towards the ringer's two points. mostly the one part of ringeris joined with "+" supply and they second track is joined to one of the pins of its controller IC.

See the example below in which the ringer's lower point is joined with "+" and the secondpoint is joined with PIN# 6 of "UI" IC(which controls ringer , vibrator and lights) this exampleis given from the circuit diagram of famous nokia handset 3310.

Ringer Controller IC:

A IC who controls the ring signals in mobile phones is normally called ringer IC and it controlringer activity. in some cases it is damaged and it would be fixed up with a new IC

replacement.

Programming:

there are such chances when an inner setting of the program running in a mobile phonecompels or sets Ringer off. you can check if the Ringer setting is correct in your mobile phone.

When we find a mobile phone with having problem of no Ringer then we should take the stepsgiven below to eliminate this problem.



Signal Faults Repairing

We are going to discuss here some techniques and steps to repair no signal condition inmobile phones irrespective of brands

Here we are doing some critical study of the components which are mostly responsible inmobile phone no signal or low signal fault. first of all I am going to advise you about somesteps to be taken while cheking and repairing no signal condition in mobil phones.

• always remove phone covers slightly because some phones like sonyericson k500i has

sticker type antenna and could be damaged while removing phone cover or disassemblingmobile phone .









Checking Of Vibrator:

If you suspect that a vibrator is damaged you can check it as the following ways.

Check if its points ar not broken if it is so you can replace this vibrator on the basis of

its shape and size because now a days all the vibrators are operate on same voltages but theirshape and size is different.

Check continuity between the two terminals of Vibrator if there is no continuity then

consider this vibrator damaged and replace it.

Tracks:

all tracks which lead to the vibrator from its micro controller are subject to create "no vibrationproblems" so if the tracks of the vibrator are damaged or open then vibrator will not getelectronic pulses form its micro controller and it will not produce vibration. Our experiment saysthat 90% set with no vibration faults are fixed only with jumpering open tracks.. see anexample below

Micro Controller IC:

A micro controller IC is used in a mobile phone to control pulses sent bye CPU so if a pulse sentby CPU to micro controller IC is not executed vibrator will not work despite of the integrity of

tracks and vibrator its self so some times this problem occurs in mobile phone that vibrator isOK , Tracks are Ok but no vibration is there then you can check IC controlling this vibrafunction you see the picture given above where a 20PIN IC is connected to vibrator and if this

IC fails to work properly then vibrator will not be able to work at all.

Programming:

there are such chances when an inner setting of the program running in a mobile phonecompels or sets vibra off. you can check if the vibrator setting is correct in your mobile phone.



When we find a mobile phone with having problem of no vibration then we should take thesteps given below to eliminate this problem.







Documents

Mobile Basic Book