.:: Complete Repair Step By Step Tutorials ::.

[obidulmomin]

All lessons here in were all simplified and a few general technical terms being reduced to make easy learning and understanding, Images and Pictures were also gathered and choose appropriately to support every aspects of learning.

These tutorials covers the following step by step lessons:

LESSON 01

Basic Information How Cellphone Works?
Learning with Block Diagram on How basically Cell-phone works?

LESSON 02

Introduction To Basic Electronics
Ohm's Law
Series Circuit
Parallel Circuit
Identifying Electronics Components and Circuit Symbols
Resistors

Capacitors
Transistors
Diodes
Fuse
Coils & Inductors
Crystal Oscillators
RF & IF Amplifiers and Filters
EMI and ESD Filters

LESSON 03

Preparing the Proper Tools For Repairing
Opening Tools and Tweezers
Soldering and Desoldering Tools
Muti Tester
SMD Rework Stations
DC Power Supply
Cleaning Kits
Reballing Kits
Working Table Equipments

LESSON 04

Safety Procedures and Proper Handling of Tools and Test Equipments on Cellphone Repair
How To Use and Read a Multimeter Tester
Test and Check up Procedures on Basic Electronics Components

LESSON 05

Introduction to
Reading Cellphone's Schematic Diagrams
Identifying Component Symbols and Layout in Schematic Diagram
How to Identify Resistor's Symbols and Layout
How to Identify Capacitor's Symbols and Layout
How to Identify Transistor's Symbols and Layout
How to Identify Diodes Symbols and Layout
How to Identify Coil Symbols and Layout
How to Identify Integrated Circuit Symbols and Layout
How to Identify DC to DC Voltage Drivers, Regulators and
Convertes Symbols and Layout
How to Identify EMI-ESD Symbols and Layout
How to Identify RF Filter Symbols and Layout
How to Identify Battery Cell Symbols and Layout
How to Identify Power Switch , Mouthpiece, Earpiece and Ringtones Speakers User Interface Symbols and Layout
How to Identify Clock Crystal Oscillator Symbols and Layout
How to Identify Fuse Symbol and Layout
How to Identify the Lines and Symbols on Schematic Diagram

LESSON 06

How to Find and Locate Components on PC BoardHow to Solder SMD Components Manually by Hand
How to Reball BGA Chips Manually by Hand
Identifying and Familiarization of Common Mobile Phones Components and Spare Parts
Liquid Crystal Display LCD's Touch Screen Panels Microphones Micro Speakers Switches Charging Pins Antenna's Batteries Battery Connectors USB connectors

Familarization: Components and Parts on Nokia Mobile Phone Handsets
Familarization: Components and Parts on Samsung Mobile Phone Handsets
Familarization: Components and Parts on Sony Ericsson Mobile Phone Handsets
Familarization: Components and Parts on Motorola Mobile Phone Handsets
Familarization: Components and Parts on iPhone Mobile Phone Handsets
Familarization: Components and Parts on Blackberry Mobile Phone Handsets
Familarization: Components and Parts on HTC Mobile Phone Handsets

Understanding Major Integrated Circuits (IC) on Mobile Phones
Power Management IC
Application Processor
Flash IC
RAM IC
Basic Hardware Handling Procedures
Proper Disassembling and Assembling Methods
How to Test Mobile phone Speaker,Buzzer or Ringer
How to Test Mobile phone Microphone or Mouthpiece
How to test Mobile Phone Charger Voltage
How to Test Mobile Phone Vibra Motor
How to check Mobile Phone Battery Voltage
How to test Power ON OFF Switch

Hardware Troubleshooting Basics
How to Troubleshoot Not Charging Issues
How charging circuit works
No Charging Response
Charger Not Supported
Not Charging
How SIM Circuits works
Insert Sim Card Problem
Invalid Sim Card
How Keypad Circuits Works
How to Map and Trace keypads Lines
Understanding The LED light Circuits
Explanation on How Audio Circuits work
Mouthpiece
Earpiece
Buzzer
Ringer
Headset
Vibra motor
How LCD Display Circuit Works

Basic Mobile Phones Hardware Repair Techniques

Basic on Software Handling
What is Flashing
What is Unlocking

[obidulmomin]

How Cellphone Works?

As a basic Part of a Technician, It is fully advice that he/she must posses a basic knowledge of what technology he or she come up to..
Before we procced further, please take a simple brief to inhanced your knowlegde about the Field of What we are going to discuss hereafter.... Now first come first we all ever wonder how does the cellphone works?

have you ever wondered how a cell phone works? What makes it different from a regular phone? what's inside of it and how do they created it?
What do all those terms like PCS, GSM, CDMA and TDMA mean?

To start with, one of the most interesting things about a cell phone is that it is actually a radio -- an extremely sophisticated radio, but a radio nonetheless. The telephone was invented by Alexander Graham Bell in 1876, and wireless communication can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a young Italian named Guglielmo Marconi). It was only natural that these two great technologies would eventually be combined.

If you prepare to take a deep knowledge, i recommended you to visit this site and have a brief of Fundamentals of Wireless Communication
A basic technician all need is just to have a simple understanding about cellphones, we do not need extreme and intimate deeper meaning about it,
that's because what we are going to take around here is to fix what those various mobile phones company created and build....to make it as simple as that... We are going to fix somewhat if their product gets busted by the end user's who bought it..

below is just a simple basic information I gathered to compensate somewhat of what we are going to learn.

Cell Phone Network Technologies:

2G Technology
There are three common technologies used by 2G cell-phone networks for transmitting information:

* Frequency division multiple access (FDMA)
* Time division multiple access (TDMA)
* Code division multiple access (CDMA)

Although these technologies sound very intimidating, you can get a good sense of how they work just by breaking down the title of each one.

The first word tells you what the access method is. The second word, division, lets you know that it splits calls based on that access method.

* FDMA puts each call on a separate frequency.
* TDMA assigns each call a certain portion of time on a designated frequency.
* CDMA gives a unique code to each call and spreads it over the available frequencies.

The last part of each name is multiple access. This simply means that more than one user can utilize each cell.

FDMA

FDMA separates the spectrum into distinct voice channels by splitting it into uniform chunks of bandwidth. To better understand FDMA, think of radio stations: Each station sends its signal at a different frequency within the available band. FDMA is used mainly for analog transmission. While it is certainly capable of carrying digital information, FDMA is not considered to be an efficient method for digital transmission.


In FDMA, each phone uses a different frequency.


TDMA

TDMA is the access method used by the Electronics Industry Alliance and the Telecommunications Industry Association for Interim Standard 54 (IS-54) and Interim Standard 136 (IS-136). Using TDMA, a narrow band that is 30 kHz wide and 6.7 milliseconds long is split time-wise into three time slots.

Narrow band means "channels" in the traditional sense. Each conversation gets the radio for one-third of the time. This is possible because voice data that has been converted to digital information is compressed so that it takes up significantly less transmission space. Therefore, TDMA has three times the capacity of an analog system using the same number of channels. TDMA systems operate in either the 800-MHz (IS-54) or 1900-MHz (IS-136) frequency bands.


TDMA splits a frequency into time slots.

Unlocking Your GSM Phone
Any GSM phone can work with any SIM card, but some service providers "lock" the phone so that it will only work with their service. If your phone is locked, you can't use it with any other service provider, whether locally or overseas. You can unlock the phone using a special code -- but it's unlikely your service provider will give it to you. There are Web sites that will give you the unlock code, some for a small fee, some for free.

GSM
TDM*A is also used as the access technology for Global System for Mobile communications (GSM). However, GSM implements TDMA in a somewhat different and incompatible way from IS-136. Think of GSM and IS-136 as two different operating systems that work on the same processor, like Windows and Linux both working on an Intel Pentium III. GSM systems use encryption to make phone calls more secure. GSM operates in the 900-MHz and 1800-MHz bands in Europe and Asia and in the 850-MHz and 1900-MHz (sometimes referred to as 1.9-GHz) band in the United States. It is used in digital cellular and PCS-based systems. GSM is also the basis for Integrated Digital Enhanced Network (IDEN), a popular system introduced by Motorola and used by Nextel.

GSM is the international standard in Europe, Australia and much of Asia and Africa. In covered areas, cell-phone users can buy one phone that will work anywhere where the standard is supported. To connect to the specific service providers in these different countries, GSM users simply switch subscriber identification module (SIM) cards. SIM cards are small removable disks that slip in and out of GSM cell phones. They store all the connection data and identification numbers you need to access a particular wireless service provider. *

Unfortunately, the 850MHz/1900-MHz GSM phones used in the United States are not compatible with the international system. If you live in the United States and need to have cell-phone access when you're overseas, you can either buy a tri-band or quad-band GSM phone and use it both at home and when traveling or just buy a GSM 900MHz/1800MHz cell phone for traveling. You can get 900MHz/1800MHz GSM phones from Planet Omni, an online electronics firm based in California. They offer a wide selection of Nokia, Motorola and Ericsson GSM phones. They don't sell international SIM cards, however. You can pick up prepaid SIM cards for a wide range of countries at Telestial.com.

CDMA

CDMA takes an entirely different approach from TDMA. CDMA, after digitizing data, spreads it out over the entire available bandwidth. Multiple calls are overlaid on each other on the channel, with each assigned a unique sequence code. CDMA is a form of spread spectrum, which simply means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range.


In CDMA, each phone's data has a unique code.

All of the users transmit in the same wide-band chunk of spectrum. Each user's signal is spread over the entire bandwidth by a unique spreading code. At the receiver, that same unique code is used to recover the signal. Because CDMA systems need to put an accurate time-stamp on each piece of a signal, it references the GPS system for this information. Between eight and 10 separate calls can be carried in the same channel space as one analog AMPS call. CDMA technology is the basis for Interim Standard 95 (IS-95) and operates in both the 800-MHz and 1900-MHz frequency bands.

Ideally, TDMA and CDMA are transparent to each other. In practice, high-power CDMA signals raise the noise floor for TDMA receivers, and high-power TDMA signals can cause overloading and jamming of CDMA receivers.

2G is a cell phone network protocol. Click here to learn about network protocols for Smartphones.

Now let's look at the distinction between multiple-band and multiple-mode technologies.

Multi-band vs. Multi-mode Cell Phones

Dual Band vs. Dual Mode
If you travel a lot, you will probably want to look for phones that offer multiple bands, multiple modes or both. Let's take a look at each of these options:

* Multiple band - A phone that has multiple-band capability can switch frequencies. For example, a dual-band TDMA phone could use TDMA services in either an 800-MHz or a 1900-MHz system. A quad-band GSM phone could use GSM service in the 850-MHz, 900-MHz, 1800-MHz or 1900-MHz band.
* Multiple mode - In cell phones, "mode" refers to the type of transmission technology used. So, a phone that supported AMPS and TDMA could switch back and forth as needed. It's important that one of the modes is AMPS -- this gives you analog service if you are in an area that doesn't have digital support.
* Multiple band/Multiple mode - The best of both worlds allows you to switch between frequency bands and transmission modes as needed.


Cellular vs. PCS

Personal Communications Services (PCS) is a wireless phone service very similar to cellular phone service, but with an emphasis on personal service and extended mobility. The term "PCS" is often used in place of "digital cellular," but true PCS means that other services like paging, caller ID and e-mail are bundled into the service.

While cellular was originally created for use in cars, PCS was designed from the ground up for greater user mobility. PCS has smaller cells and therefore requires a larger number of antennas to cover a geographic area. PCS phones use frequencies between 1.85 and 1.99 GHz (1850 MHz to 1990 MHz).

Technically, cellular systems in the United States operate in the 824-MHz to 894-MHz frequency bands; PCS operates in the 1850-MHz to 1990-MHz bands. And while it is based on TDMA, PCS has 200-kHz channel spacing and eight time slots instead of the typical 30-kHz channel spacing and three time slots found in digital cellular.

Changing bands or modes is done automatically by phones that support these options. Usually the phone will have a default option set, such as 1900-MHz TDMA, and will try to connect at that frequency with that technology first. If it supports dual bands, it will switch to 800 MHz if it cannot connect at 1900 MHz. And if the phone supports more than one mode, it will try the digital mode(s) first, then switch to analog.

You can find both dual-mode and tri-mode phones. The term "tri-mode" can be deceptive. It may mean that the phone supports two digital technologies, such as CDMA and TDMA, as well as analog. In that case, it is a true tri-mode phone. But it can also mean that it supports one digital technology in two bands and also offers analog support. A popular version of the tri-mode type of phone for people who do a lot of international traveling has GSM service in the 900-MHz band for Europe and Asia and the 1900-MHz band for the United States, in addition to the analog service. Technically, this is a dual-mode phone, and one of those modes (GSM) supports two bands.

3G and 3GS Technology

In the next section, we'll take a look at 3G mobile-phone technology.

3G technology is the latest in mobile communications. 3G stands for "third generation" -- this makes analog cellular technology generation one and digital/PCS generation two. 3G technology is intended for the true multimedia cell phone -- typically called smartphones -- and features increased bandwidth and transfer rates to accommodate Web-based applications and phone-based audio and video files.

3G comprises several cellular access technologies. The three most common ones as of 2005 are:

* CDMA2000 - based on 2G Code Division Multiple Access (see Cellular Access Technologies)
* WCDMA (UMTS) - Wideband Code Division Multiple Access
* TD-SCDMA - Time-division Synchronous Code-division Multiple Access
3G networks have potential transfer speeds of up to 3 Mbps (about 15 seconds to download a 3-minute MP3 song). For comparison, the fastest 2G phones can achieve up to 144Kbps (about 8 minutes to download a 3-minute song). 3G's high data rates are ideal for downloading information from the Internet and sending and receiving large, multimedia files. 3G phones are like mini-laptops and can accommodate broadband applications like video conferencing, receiving streaming video from the Web, sending and receiving faxes and instantly downloading e-mail messages with attachments.

3GS feels wonderfully familiar – it’s design is almost identical to the 3G, and it’s not until you switch the device on that you start to appreciate the differences. The “S” stands for speed – Apple has used a faster processor in the 3GS, and the impact is immediate, with applications loading more briskly, programs running noticeably faster, and the already slick user-interface getting an extra layer of go-faster stripes. It’s also HSDPA compatible, a step up from 3G, meaning it can surf the web at faster speeds. Battery life is longer too; I was able to squeeze a full day out of my iPhone without needing to give it a lunchtime charging boost.

[obidulmomin]

Learning with Block Diagram on How basically Cell-phone works?

How basically Cell-phone works?

In this lesson we are going to take a brief familiarization of a typical block diagram of a cellphone.
Block Diagram can help us understand the flow of a certain part of a cellphone's circuit.
A Cell-phone handset is basically composed of two sections,
which is RF and Baseband Sections.

RF
RF refers to radio frequency, the mode of communication for wireless technologies of all kinds, including cordless phones, radar, ham radio, GPS, and radio and television broadcasts. RF technology is so much a part of our lives we scarcely notice it for its ubiquity. From baby monitors to cell phones, Bluetooth® to remote control toys, RF waves are all around us. RF waves are electromagnetic waves which propagate at the speed of light, or 186,000 miles per second (300,000 km/s). The frequencies of RF waves, however, are slower than those of visible light, making RF waves invisible to the human eye.


Baseband
In signal processing, baseband describes signals and systems whose range of frequencies is measured from zero to a maximum bandwidth or highest signal frequency. It is sometimes used as a noun for a band of frequencies starting at zero.
In telecommunications, it is the frequency range occupied by a message signal prior to modulation.
It can be considered as a synonym to low-pass.
Baseband is also sometimes used as a general term for part of the physical components of a wireless communications product. Typically, it includes the control circuitry (microprocessor), the power supply, and amplifiers.
A baseband processor is an IC that is mainly used in a mobile phone to process communication functions.

Basically Baseband also composed of to sections which is the Analog and Digital Processing Sections. So, we are going to separate each other for better and easier to understand.
Cell-phone have three different sections which is the following.
I prepare this to be simple and easy instead of using or explaining it with deep technical terms .
In this manner, it is easy for us to understand the concepts and methods of how basically the cellphone works.

Cell-phone have three sections since baseband is differentiated by into two which is the Analog and Digital function while the RF section remains as a whole circuit section.. which is the following cosists.
1. Radio Frequency (RF Section)
2. The Analog Baseband Processor
3. And the Digital Baseband Processor.

block1 copy.jpg

Radio Frequency Processing Section
The RF section is the part of the cell-phone circuit is also known as RF Transceiver.
It is the section that transmit and receive certain frequency to a network and synchronize to other phone.


The RF - A radio section is based on two main Circuits.
1 Transmitter
2 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 a reciever is simply like radios which are used to recieve transmissions(Radiation) which is spread in the air by any transmitter on a specific frequency.
The two way communication is made possible by setting two transmitters and two recievers sycronized 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 is syncronised with the recieving frequency of first cell phone. So first cell phone transmits its radiation in the air while the other phone listens it and same process is present in the opposit side. 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 theory prescribed before. the today's technology will be discussed in later on.

block2 copy.jpg

Analog Baseband Processor
A/D and D/A section
The analog baseband processing section is composed of different types of circuits.
This section converts and process the analog to digital (A/D) signals and digital to analog signals (D/A).
Control section
This is the section acts as the controller of the the input and output of any analog and digital signal.

Power Management

A power management section in mobile phones is designed to handle energy matters that is consumed in mobile phones. 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 desired Voltages and currenst to the other sections of a phone. this section takes power from a battery (which is figured commonly 3.6 Volts)and in some places it converts or step down to various volts like 2.8 V 1.8V 1.6V etc.while on other place it also
steps up the voltage like 4.8 V. this section is commonly designed around a power IC(and integrated circuit) which is used to distribute and regulate the voltage used in other components.
The Charging section is based on a charging IC which takes power from an external source and gives it to battery to make it again power up when it is exhausted. this section uses convertibly 6.4 V from an external battery charger and regulates it to 5.8V wile giving it to battery. The battery is made charged by this process and it is ready to use for the next session (a battery session is a time which is provided by the manufacturer of a cell phone for standby by condition of a mobile phone or talk condition.)

Audio Codecs Section
This section where analog and digital audio properties being process like the microphone, earpiece speaker headset and ring-tones and also the vibrator circuits.

block3 copy.jpg

Digital Baseband Processor

This is the part where All Application being process. Digital Baseband Processor section is used in mobile phones to handle data input and ouput signal like switching, driving applications commands and memory accessing and executing.
These are the parts and sections o a Digital Baseband Circuit were installed.
CPU
CPU( Centeral Processing Unit) The Central Processing Unit (CPU) is responsible for interpreting and executing most of the commands from the users interface. It is often called the "brains" of the microprocessor, central processor, "the brains of the computer"
Flash and Memory Storage Circuits
*RAM( Random Access Memory)
*ROM,Flash(Read Only Memory
Interfaces such as the following were also part on this section:
*Blutooth
*Wi-fi
*Camera
*Screen Display
*Keypads
*USB
*SIM-Card

block4 copy.jpg

Here a typical overview of a block diagram on latest mobile phone designs.

cellphone block diagram copy.jpg

Various mobile phones have different concepts and design on every aspects, but the methods and operational flow are all exactly the same. It differs on how and what certain IC chips and parts they are being used and installed to a certain mobile phone circuitry.

[obidulmomin]

Introduction to Basic Electronics

Definition of Electronics:
Electronics is the branch of science that deals with the study of flow and control of electrons (electricity) and the study of their behavior and effects in vacuums, gases, and semiconductors, and with devices using such electrons. This control of electrons is accomplished by devices that resist, carry, select, steer, switch, store, manipulate, and exploit the electron.

Electronics isn't always easy, but you can learn. And you can do it without memorizing theories and formulas belong in a Physics text. the focus of this program is learning how things work. Electronics may defined as an art of knowledge to make such impossible things work. Things such as Televisions, AM/FM Radios, Computers and ob course the mobile phones and etc. We are surrounded by electronics....

Learning how things work can be fun.
With this skill you can Build things.
make better use of things
and repair things..
have better job opportunities

An important part of learning electronics
is the the need to visualize the action inside a piece of equipment. In electronics things happen at a sub-atomic level. to understand what is happening, you need a mental picture, a visualization of events you can see directly. You need a in your mind of how events are turned on and off. you need to visualize signals being amplified and attenuated. ( These are long words for being made bigger and smaller )

take an overview of electronic equipment. Inside anything what's happening can be describe as some kind of source delivering power to some kind of a load. The terms source and load become clearer as you can discover a few basics. A source is where the energy comes from. A load is what does the work. When power is delivered to a load, the load produces sound, heat, pictures or anything else that can be produced electronically..

[obidulmomin]

Ohm's Law

What is Ohm's Law?
Ohm's Law is made from 3 mathematical equations that shows the relationship between electric voltage, current and resistance.

What is voltage?
An anology would be a huge water tank filled with thousands of gallons of water high on a hill.
The difference between the pressure of water in the tank and the water that comes out of a pipe connected at the bottom leading to a faucet is determined by the size of the pipe and the size of the outlet of the faucet. This difference of pressure between the two can be thought of as potential Voltage.


What is current?
An analogy would be the amount of flow determined by the pressure (voltage) of the water thru the pipes leading to a faucet. The term current refers to the quantity, volume or intensity of electrical flow, as opposed to voltage, which refers to the force or "pressure" causing the current flow.

What is resistance?
An analogy would be the size of the water pipes and the size of the faucet. The larger the pipe and the faucet (less resistance), the more water that comes out! The smaller the pipe and faucet, (more resistance), the less water that comes out! This can be thought of as resistance to the flow of the water current.
All three of these: voltage, current and resistance directly interact in Ohm's law.
Change any two of them and you effect the third.

Info: Ohm's Law was named after Bavarian mathematician and physicist Georg Ohm.


Ohm's Law can be stated as mathematical equations, all derived from the
same principle.
In the following equations,
V is voltage measured in volts (the size of the water tank),

I is current measured in amperes (related to the pressure (Voltage) of water thru the pipes and faucet) and

R is resistance measured in ohms as related to the size of the pipes and faucet:

V = I x R (Voltage = Current multiplied by Resistance)

R = V / I (Resistance = Voltage divided by Current)

I = V / R (Current = Voltage Divided by Resistance)

Knowing any two of the values of a circuit, one can determine (calculate) the third, using Ohm's Law.

For example, to find the Voltage in a circuit:

If the circuit has a current of 2 amperes, and a resistance of 1 ohm, (< these are the two "knowns"), then according to Ohms Law and the formulas above, voltage equals current multiplied by resistance:

(V = 2 amperes x 1 ohm = 2 volts).

To find the current in the same circuit above assuming we did not know it but we know the voltage and resistance:
I = 2 volts divided by the resistance 1 ohm = 2 amperes.

In this third example we know the current (2 amperes) and the voltage (2 volts)....what is the resistance?
Substituting the formula:
R = Volts divided by the current (2 volts divided by 2 amperes = 1 ohm

Sometimes it's very helpful to associate these formulas Visually. The Ohms Law "wheels" and graphics below can be a very useful tool to jog your memory and help you to understand their relationship.

ohmchart.gif

The wheel above is divided into three sections:

Volts V (on top of the dividing line)
Amps (amperes) I (lower left below the dividing line)
Resistance R (lower right below the dividing line)
X represents the (multiply by sign)
Memorize this wheel

To use, just cover the unknown quantity you need with your minds eye and what is left is the formula to find the unknown.

Example:

To find the current of a circuit (I), just cover the I or Amps section in your mines eye and what remains is the V volts above the dividing line and the R ohms (resistance) below it. Now substitute the known values. Just divided the known volts by the known resistance.
Your answer will be the current in the circuit.
The same procedure is used to find the volts or resistance of a circuit!

Here is another example:

You know the current and the resistance in a circuit but you want to find out the voltage.

Just cover the voltage section with your minds eye...what's left is the I X R sections. Just multiply the I value times the R value to get your answer! Practice with the wheel and you'll be surprised at how well it works to help you remember the formulas without trying!

ohmslaw1.gif

This Ohm's Law Triangle graphic is also helpful to learn the formulas.
Just cover the unknown value and follow the graphic as in the yellow wheel examples above.

You'll have to insert the X between the I and R in the graphic and imagine the horizontal divide line but the principal is just the same.

ohmlsawwheel.gif

In the above Ohm's law wheel you'll notice that is has an added section (P) for Power and the letter E* has been used instead of the letter V for voltage.
This wheel is used in the exact same fashion as the other wheels and graphics above.
You will also notice in the blue/green areas there are only two known values with the unknown value in the yellow sections. The red bars separate the four units of interest.

An example of the use of this wheel is:
Let's say that you know the power and the current in a circuit and want to know the voltage.
Find your unknown value in the yellow areas (V or E* in this wheel) and just look outward and pick the values that you do know. These would be the P and the I. Substitute your values in the formula, (P divided by I) do the math and you have your answer!

Info: Typically, Ohm's Law is only applied to DC circuits and not AC circuits.
* The letter "E" is sometimes used in representations of Ohm's Law for voltage instead of the "V" as in the wheel above.

Ohm's Law Calculator

[obidulmomin]

Series Circuit

A circuit composed solely of components connected in series is known as a series circuit

A Simple Series Circuit

Let's start with a series circuit consisting of three resistors and a single battery.
The first principle to understand about series circuits is that the amount of current is the same through any component in the circuit. This is because there is only one path for electrons to flow in a series circuit, and because free electrons flow through conductors like marbles in a tube, the rate of flow (marble speed) at any point in the circuit (tube) at any specific point in time must be equal.
From the way that the 9 volt battery is arranged, we can tell that the electrons in this circuit will flow in a counter-clockwise direction, from point 4 to 3 to 2 to 1 and back to 4. However, we have one source of voltage and three resistances. How do we use Ohm's Law here?
An important caveat to Ohm's Law is that all quantities (voltage, current, resistance, and power) must relate to each other in terms of the same two points in a circuit. For instance, with a single-battery, single-resistor circuit, we could easily calculate any quantity because they all applied to the same two points in the circuit:


Since points 1 and 2 are connected together with wire of negligible resistance, as are points 3 and 4, we can say that point 1 is electrically common to point 2, and that point 3 is electrically common to point 4. Since we know we have 9 volts of electromotive force between points 1 and 4 (directly across the battery), and since point 2 is common to point 1 and point 3 common to point 4, we must also have 9 volts between points 2 and 3 (directly across the resistor). Therefore, we can apply Ohm's Law (I = E/R) to the current through the resistor, because we know the voltage (E) across the resistor and the resistance (R) of that resistor. All terms (E, I, R) apply to the same two points in the circuit, to that same resistor, so we can use the Ohm's Law formula with no reservation.
However, in circuits containing more than one resistor, we must be careful in how we apply Ohm's Law. In the three-resistor example circuit below, we know that we have 9 volts between points 1 and 4, which is the amount of electromotive force trying to push electrons through the series combination of R1, R2, and R3. However, we cannot take the value of 9 volts and divide it by 3k, 10k or 5k Ω to try to find a current value, because we don't know how much voltage is across any one of those resistors, individually.

The figure of 9 volts is a total quantity for the whole circuit, whereas the figures of 3k, 10k, and 5k Ω are individual quantities for individual resistors. If we were to plug a figure for total voltage into an Ohm's Law equation with a figure for individual resistance, the result would not relate accurately to any quantity in the real circuit.
For R1, Ohm's Law will relate the amount of voltage across R1 with the current through R1, given R1's resistance, 3kΩ:

But, since we don't know the voltage across R1 (only the total voltage supplied by the battery across the three-resistor series combination) and we don't know the current through R1, we can't do any calculations with either formula. The same goes for R2 and R3: we can apply the Ohm's Law equations if and only if all terms are representative of their respective quantities between the same two points in the circuit.
So what can we do? We know the voltage of the source (9 volts) applied across the series combination of R1, R2, and R3, and we know the resistances of each resistor, but since those quantities aren't in the same context, we can't use Ohm's Law to determine the circuit current. If only we knew what the total resistance was for the circuit: then we could calculate total current with our figure for total voltage (I=E/R).
This brings us to the second principle of series circuits: the total resistance of any series circuit is equal to the sum of the individual resistances. This should make intuitive sense: the more resistors in series that the electrons must flow through, the more difficult it will be for those electrons to flow. In the example problem, we had a 3 kΩ, 10 kΩ, and 5 kΩ resistor in series, giving us a total resistance of 18 kΩ:

In essence, we've calculated the equivalent resistance of R1, R2, and R3 combined. Knowing this, we could re-draw the circuit with a single equivalent resistor representing the series combination of R1, R2, and R3:

Now we have all the necessary information to calculate circuit current, because we have the voltage between points 1 and 4 (9 volts) and the resistance between points 1 and 4 (18 kΩ):

1.png

Knowing that current is equal through all components of a series circuit (and we just determined the current through the battery), we can go back to our original circuit schematic and note the current through each component:

2.png

Now that we know the amount of current through each resistor, we can use Ohm's Law to determine the voltage drop across each one (applying Ohm's Law in its proper context):

3.png

Notice the voltage drops across each resistor, and how the sum of the voltage drops (1.5 + 5 + 2.5) is equal to the battery (supply) voltage: 9 volts. This is the third principle of series circuits: that the supply voltage is equal to the sum of the individual voltage drops.
However, the method we just used to analyze this simple series circuit can be streamlined for better understanding. By using a table to list all voltages, currents, and resistances in the circuit, it becomes very easy to see which of those quantities can be properly related in any Ohm's Law equation:

4.png

The rule with such a table is to apply Ohm's Law only to the values within each vertical column. For instance, ER1 only with IR1 and R1; ER2 only with IR2 and R2; etc. You begin your analysis by filling in those elements of the table that are given to you from the beginning:

5.png

As you can see from the arrangement of the data, we can't apply the 9 volts of ET (total voltage) to any of the resistances (R1, R2, or R3) in any Ohm's Law formula because they're in different columns. The 9 volts of battery voltage is not applied directly across R1, R2, or R3. However, we can use our "rules" of series circuits to fill in blank spots on a horizontal row. In this case, we can use the series rule of resistances to determine a total resistance from the sum of individual resistances:


6.png

Now, with a value for total resistance inserted into the rightmost ("Total") column, we can apply Ohm's Law of I=E/R to total voltage and total resistance to arrive at a total current of 500 µA:

Then, knowing that the current is shared equally by all components of a series circuit (another "rule" of series circuits), we can fill in the currents for each resistor from the current figure just calculated:

Finally, we can use Ohm's Law to determine the voltage drop across each resistor, one column at a time:

Just for fun, we can use a computer to analyze this very same circuit automatically. It will be a good way to verify our calculations and also become more familiar with computer analysis. First, we have to describe the circuit to the computer in a format recognizable by the software. The SPICE program we'll be using requires that all electrically unique points in a circuit be numbered, and component placement is understood by which of those numbered points, or "nodes," they share. For clarity, I numbered the four corners of our example circuit 1 through 4. SPICE, however, demands that there be a node zero somewhere in the circuit, so I'll re-draw the circuit, changing the numbering scheme slightly:

7.png

All I've done here is re-numbered the lower-left corner of the circuit 0 instead of 4. Now, I can enter several lines of text into a computer file describing the circuit in terms SPICE will understand, complete with a couple of extra lines of code directing the program to display voltage and current data for our viewing pleasure. This computer file is known as the netlist in SPICE terminology:

series circuit
v1 1 0
r1 1 2 3k
r2 2 3 10k
r3 3 0 5k
.dc v1 9 9 1
.print dc v(1,2) v(2,3) v(3,0)
.end


Now, all I have to do is run the SPICE program to process the netlist and output the results:

v1 v(1,2) v(2,3) v(3) i(v1)
9.000E+00 1.500E+00 5.000E+00 2.500E+00 -5.000E-04


This printout is telling us the battery voltage is 9 volts, and the voltage drops across R1, R2, and R3 are 1.5 volts, 5 volts, and 2.5 volts, respectively. Voltage drops across any component in SPICE are referenced by the node numbers the component lies between, so v(1,2) is referencing the voltage between nodes 1 and 2 in the circuit, which are the points between which R1 is located. The order of node numbers is important: when SPICE outputs a figure for v(1,2), it regards the polarity the same way as if we were holding a voltmeter with the red test lead on node 1 and the black test lead on node 2.
We also have a display showing current (albeit with a negative value) at 0.5 milliamps, or 500 microamps. So our mathematical analysis has been vindicated by the computer. This figure appears as a negative number in the SPICE analysis, due to a quirk in the way SPICE handles current calculations.
In summary, a series circuit is defined as having only one path for electrons to flow. From this definition, three rules of series circuits follow: all components share the same current; resistances add to equal a larger, total resistance; and voltage drops add to equal a larger, total voltage. All of these rules find root in the definition of a series circuit. If you understand that definition fully, then the rules are nothing more than footnotes to the definition.

REVIEW:
Components in a series circuit share the same current: ITotal = I1 = I2 = . . . In
Total resistance in a series circuit is equal to the sum of the individual resistances: RTotal = R1 + R2 + . . . Rn
Total voltage in a series circuit is equal to the sum of the individual voltage drops: ETotal = E1 + E2 + . . . En

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One connected completely in parallel is known as a parallel circuit.

Simple Parallel Circuit
Let's start with a parallel circuit consisting of three resistors and a single battery:

The first principle to understand about parallel circuits is that the voltage is equal across all components in the circuit. This is because there are only two sets of electrically common points in a parallel circuit, and voltage measured between sets of common points must always be the same at any given time. Therefore, in the above circuit, the voltage across R1 is equal to the voltage across R2 which is equal to the voltage across R3 which is equal to the voltage across the battery. This equality of voltages can be represented in another table for our starting values:

Just as in the case of series circuits, the same caveat for Ohm's Law applies: values for voltage, current, and resistance must be in the same context in order for the calculations to work correctly. However, in the above example circuit, we can immediately apply Ohm's Law to each resistor to find its current because we know the voltage across each resistor (9 volts) and the resistance of each resistor:

1.png
2.png

At this point we still don't know what the total current or total resistance for this parallel circuit is, so we can't apply Ohm's Law to the rightmost ("Total") column. However, if we think carefully about what is happening it should become apparent that the total current must equal the sum of all individual resistor ("branch") currents:

3.png

As the total current exits the negative (-) battery terminal at point 8 and travels through the circuit, some of the flow splits off at point 7 to go up through R1, some more splits off at point 6 to go up through R2, and the remainder goes up through R3. Like a river branching into several smaller streams, the combined flow rates of all streams must equal the flow rate of the whole river. The same thing is encountered where the currents through R1, R2, and R3 join to flow back to the positive terminal of the battery (+) toward point 1: the flow of electrons from point 2 to point 1 must equal the sum of the (branch) currents through R1, R2, and R3.
This is the second principle of parallel circuits: the total circuit current is equal to the sum of the individual branch currents. Using this principle, we can fill in the IT spot on our table with the sum of IR1, IR2, and IR3:

Finally, applying Ohm's Law to the rightmost ("Total") column, we can calculate the total circuit resistance:

4.png

Please note something very important here. The total circuit resistance is only 625 Ω: less than any one of the individual resistors. In the series circuit, where the total resistance was the sum of the individual resistances, the total was bound to be greater than any one of the resistors individually. Here in the parallel circuit, however, the opposite is true: we say that the individual resistances diminish rather than add to make the total. This principle completes our triad of "rules" for parallel circuits, just as series circuits were found to have three rules for voltage, current, and resistance. Mathematically, the relationship between total resistance and individual resistances in a parallel circuit looks like this:

6.png

The same basic form of equation works for any number of resistors connected together in parallel, just add as many 1/R terms on the denominator of the fraction as needed to accommodate all parallel resistors in the circuit.
Just as with the series circuit, we can use computer analysis to double-check our calculations. First, of course, we have to describe our example circuit to the computer in terms it can understand. I'll start by re-drawing the circuit:

Once again we find that the original numbering scheme used to identify points in the circuit will have to be altered for the benefit of SPICE. In SPICE, all electrically common points must share identical node numbers. This is how SPICE knows what's connected to what, and how. In a simple parallel circuit, all points are electrically common in one of two sets of points. For our example circuit, the wire connecting the tops of all the components will have one node number and the wire connecting the bottoms of the components will have the other. Staying true to the convention of including zero as a node number, I choose the numbers 0 and 1:

6.png

An example like this makes the rationale of node numbers in SPICE fairly clear to understand. By having all components share common sets of numbers, the computer "knows" they're all connected in parallel with each other.
In order to display branch currents in SPICE, we need to insert zero-voltage sources in line (in series) with each resistor, and then reference our current measurements to those sources. For whatever reason, the creators of the SPICE program made it so that current could only be calculated through a voltage source. This is a somewhat annoying demand of the SPICE simulation program. With each of these "dummy" voltage sources added, some new node numbers must be created to connect them to their respective branch resistors:
7.png

The dummy voltage sources are all set at 0 volts so as to have no impact on the operation of the circuit. The circuit description file, or netlist, looks like this:

Parallel circuit
v1 1 0
r1 2 0 10k
r2 3 0 2k
r3 4 0 1k
vr1 1 2 dc 0
vr2 1 3 dc 0
vr3 1 4 dc 0
.dc v1 9 9 1
.print dc v(2,0) v(3,0) v(4,0)
.print dc i(vr1) i(vr2) i(vr3)
.end


Running the computer analysis, we get these results (I've annotated the printout with descriptive labels):

v1 v(2) v(3) v(4)
9.000E+00 9.000E+00 9.000E+00 9.000E+00
battery R1 voltage R2 voltage R3 voltage
voltage


v1 i(vr1) i(vr2) i(vr3)
9.000E+00 9.000E-04 4.500E-03 9.000E-03
battery R1 current R2 current R3 current
voltage


These values do indeed match those calculated through Ohm's Law earlier: 0.9 mA for IR1, 4.5 mA for IR2, and 9 mA for IR3. Being connected in parallel, of course, all resistors have the same voltage dropped across them (9 volts, same as the battery).
In summary, a parallel circuit is defined as one where all components are connected between the same set of electrically common points. Another way of saying this is that all components are connected across each other's terminals. From this definition, three rules of parallel circuits follow: all components share the same voltage; resistances diminish to equal a smaller, total resistance; and branch currents add to equal a larger, total current. Just as in the case of series circuits, all of these rules find root in the definition of a parallel circuit. If you understand that definition fully, then the rules are nothing more than footnotes to the definition.

REVIEW:
Components in a parallel circuit share the same voltage: ETotal = E1 = E2 = . . . En
Total resistance in a parallel circuit is less than any of the individual resistances: RTotal = 1 / (1/R1 + 1/R2 + . . . 1/Rn)
Total current in a parallel circuit is equal to the sum of the individual branch currents: ITotal = I1 + I2 + . . . In.

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Identifying Electronic Component and Symbol

Identifying Electronic Component and Symbol is very important rule
when fixing mobile phones problems..
Be familiar of its circuit symbols below for easy troubleshooting guide.
Every Electronics Component has its own symbols visualizing it;s function in every circuit diagram...
This is a very big help especially when working on hardware problems.
This Components Symbol is a standard guides when reading or writing service
schematic diagram with various mobile phone products.

circuit-symbols.png

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SMT Resistor

SMT Resistor ( Unprinted )
In Mobile Phones Surface Mount Molded (SMD) Resistor where not printed with numerical value and it is left blank, the problem is that it is too tiny or small to print at..
You can refer only its value by an aide of Schematic Diagram Available for that certain products. Or you can Identify and check its value by using Resistance Tester...

1.jpg

In Schematic Diagram Its Original value where indicated: For Example:

Resistances less than 1000 ohms or 1K with ''R'' indicated in the middle indicates a decimal point like:

4R7 = 4.7Ω
2R2 = 2.2Ω

and the rest just like how it does indicated like:

100Ω = 100 ohms
220Ω = 200 ohms

and up
4.7K = 4.7 kiloohms


The Printed SMD Resistor

Zero ohm resistors Surface mounted resistors are printed with numerical values in a code related to that used on axial resistors.

2.jpg

Standard-tolerance Surface Mount Technology (SMT) resistors are marked with a three-digit code, in which the first two digits are the first two significant digits of the value and the third digit is the power of ten (the number of zeroes). For example:

334 = 33 × 10,000 Ω = 330 kΩ
222 = 22 × 100 Ω = 2.2 kΩ
473 = 47 × 1,000 Ω = 47 kΩ
105 = 10 × 100,000 Ω = 1 MΩ


Resistances less than 100 ohms are written: 100, 220, 470. The final zero represents ten to the power zero, which is 1. For example:

100 = 10 × 1 Ω = 10 Ω
220 = 22 × 1 Ω = 22 Ω

Resistances less than 10 ohms have 'R' to indicate the position of the decimal point (radix point). For example:

4R7 = 4.7 Ω
0R22 = 0.22 Ω
0R01 = 0.01 Ω

Precision resistors are marked with a four-digit code, in which the first three digits are the significant figures and the fourth is the power of ten. For example:

1001 = 100 × 10 ohms = 1 kΩ
4992 = 499 × 100 ohms = 49.9 kΩ
1000 = 100 × 1 ohm = 100 Ω


"000" and "0000" sometimes appear as values on surface-mount zero-ohm links, since these have (approximately) zero resistance.

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Lesson-02 Part-06 SMD Capacitor

The types of capacitor which is commonly used in small space circuit like the cellphone uses the Tantalum type of capacitor,
Tantalum capacitors are used in smaller electronic devices including portable telephones, pagers, personal computers, and automotive electronics.
It also offer smaller size and lower leakage than standard. .
There are two types of Capacitors used in Mobile Phones Circuits,
The Polarized and Non-Polarized Capacitors.
This are the Capacitors may look like that are being used in mobile phones circuit.

1.jpg

The Polarized Capacitor
Tantalum Capacitors which is polarized, and may be used in DC circuits. Typical values range form 0.1uF to 470uF.
Standard Tantalum values change in multiples of 10, 22, 33, and 47. Normal Temperature Coefficient [TC] for Tantalum Capacitors is +5%.
Polarized capacitors are typically used in large voltage situations, such as DC line filtering to reduce noise related to uneven voltage levels after rectification from an AC source. Mainly measured in microfarads. Polarity is critical to these devices. They are marked with the voltage rating (usually double the circuit voltage used) as well as the farad marking.

2.jpg

Non-Polarized Capacitor
Non-polarized are similar to polarized except the plates are similar metal.

Polarized caps are typically used in large voltage situations, such as DC line filtering to reduce noise related to uneven voltage levels after rectification from an AC source. Mainly measured in microfarads. Polarity is critical to these devices. They are marked with the voltage rating (usually double the circuit voltage used) as well as the farad marking.

3.jpg

non-polarized caps are typically used in low voltage situations, both AC and DC. Polarity is not critical. Measured in pico farads typically.

Decimal multiplier prefixes are in common use to simplify and shorten the notations of quantities such as component values.
Capacitance, for example, is measured in Farads, but the Farad is far too large a unit to be of practical use in most cases. For convenience, we use sub-multiples to save a lot of figures. For example, instead of writing 0.000000000001 Farads, we write 1pF (1 picofarad).
The more common prefixes and the relationships to one another are as follows.

Abbrev.----Prefix-----------Multiply by-----------or
p----------pico------------0.000000000001-----10^-12
n----------nano-----------0.000000001---------10^-9
µ----------micro-----------0.000001------------10^-6
m----------milli------------0.001----------------10^-3
- ----------UNIT-----------1--------------------10⁰
k-----------kilo------------1000-----------------10³
M----------mega----------1000000--------------10⁶

Units

1000 pico units = 1 nano unit
1000 nano units = 1 micro unit
1000 micro units = 1 milli unit
1000 milli units = 1 unit
1000 units = 1 kilo unit
1000 kilo units = 1 mega unit

Tolerance

All components differ from their marked value by some amount. Tolerance specifies the maximum allowed deviation from the specified value. Tolerances are normally expressed as a percentage of the nominal value.
For example, a component with a marked value of 100 and a tolerance of 5% could actually be any value between 5% below the marked value (95) and 5% above the marked value (105).