Itroduction
it's easy to learn about mobile repairing. there is very good scope of regular income. you just need to visit our page regularly and learn about it. the course designed to build up the capacity of self-employment in the field of mobile handset repairing.
1. Online Mobile
Repairing Course Free
2. Learn Mobile Repairing With
Modern Tools
3. Students Can Starts Their
Own Business
Scope For Students
1. Student Can Start Their Own
Business In Mobile Repairing Field.
2. Student Can Work As A
Technician In A Mobile Repairing Service Centre.
3. Student Can Find Job in Cell
Phone Industry
Course Overview
1. Introduction and Identification of PCB
2. Short forms
3. Basic Electronics
4. Mobile Repairing Tools and Equipment
5. Fault finding
6. Identification of tools and their use
7. Software issues
1. Introduction and identification of PCB : -
PCB od mobile phone : -
The PCB of any mobile phoneor smartphone (Android and iPhone) of any brand namely
Nokia, iPhone, Samsung, Motorola, Huawei, Lenovo, LG, Mobicel, Motorola, Oppo,
Vivo, Xiaomi, China Mobile Phones etc is divided into several parts mainly : (1) Network
Section; and (2) Power Section.
VIVO Y91 PCB example
What is SMD Components?
Mobile Phone Related Short Forms
1G - First Generation In
Mobile Telephony.
2G - Second Generation
In Mobile Telephony.
3G - Third Generation
In Mobile Telephony.
4G - Fourth Generation
In Mobile Telephony.
5G - Fifth Generation
In Mobile Telephony.
AC - Alternate
Current.
DC - Direct Current.
BGA - Ball Grid Array.
CDMA - Code Division Multiple
Access.
CPU – Central Processing Unit
DCT – Digital Core Technology
GSM – Global System for Mobile
Communication
IMEI – International Mobile
Equipment Idendity
IC - Integrated Circuit
LED – Light Emitting Diode
PDA – Personal Digital Assistant
PFO – Power Frequency
Oscillator
PCB – Printed Circuit Board
RAM – Random Access Memory
RF – Radio Frequency
ROM – Read Only Memory
RTC – Real Time Clock
RX – Receive
SMD – Surface Mount Device
2. Basic
Electronics: - Before learning about mobile repairing
we have to know about basic electronics and basic electronic components. There in
a mother board we saw lots of components let’s gain some knowledge about those
components.
Resistor:
- A resistor impedes the flow of electricity through a circuit. Resistors have a set value. Since voltage,
current and resistance are related through Ohm’s law, resistors are a good way
to control voltage and current in your circuit.
Color code
Tolerance: Gold = within 5%
Black: 0
Brown 1
Red: 2
Orange: 3
Yellow: 4
Green: 5
Blue: 6
Violet: 7
Gray: 8
White: 9
Units
Knowing your units is important Kilo and Mega are common in resistors Milli, micro, nano and Pico can be used in other components
K (kilo) = 1,000 M (mega) = 1,000,000 M (milli) = 1/1,000 u (micro) = 1/1,000,000 n (nano) = 1/1,000,000,000 (one trillionth) p (pico) = 1 / 1,000,000,000,000 (one quadrillionth)
Variable
resistor / Potentiometer: - A potentiometer is a variable resistor. As
you manually turn a dial, the resistance
changes.
How a variable resistor works: - As the dial/wiper turns, electricity must go through more or less of the resistive strip. In series, the change in resistance means a change in voltage.
So as you turn the dial/wiper, you get a change in voltage.
Capacitor : - A capacitor stores electrical energy. This pool of electrons is available for
electronic components to use.
Capacitance is measured in Farads. The small capacitors usually used in electronics are often measured in microfarads and nanofarads.
Some capacitors are polarized.
Note the different length terminals on one of the capacitors.
Polarity of capacitors
The shorter terminal goes on the negative side. The stripe is on the
negative terminal side of the capacitor. The board is marked for positive or negative.
Diode circuit protection
In a DPDT switch, if polarity is wrong, the motor will run backwards. In an electronic circuit, if the polarity is wrong, you can fry— your components. A diode in your system will help to prevent problems.
Light
emitting diode (LED)
A light emitting diode is a Semiconductor light source. When electricity is passing through the diode, it emits light.
Transistors: - A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. This is our electronic switch
How a transistor works: - A voltage or current applied to one pair of the transistor’s terminals changes the current through another pair of terminals. A transistor is composed of semiconductor material with at least three terminals for connection to an external circuit.
Transistors have 3 pins
For these transistors :
Collector
Emitter
base
Terminology
1.
BJT versus FET
2.
Bipolar junction transistor.
Useful as amplifiers. Collector, Emitter, Base
3.
Field-effect transistor.
Useful as motor drivers. Source, Drain, Gate
MOSFET: Metal-oxide-semiconductor FET
4.
NPN (N-channel FET) versus PNP (P-channel FET)
5.
NPN versus PNP is how the semiconductors are layered.
NPN: Not pointing in PNP: Pointing
Integrated circuit: - An integrated circuit (IC) is a set of transistors that is the controller or ‘brain’ of an electronic circuit. An input is received, an output is sent out. Modern microprocessor ICs can have billions of transistors per square inch!
What an IC can do for us?
Billions of electronically controlled on/off switches (transistors) is how the microprocessor in a digital computer ‘thinks’ and functions. A computer has a wide range of tasks to perform. But other ICs can complete simpler, discrete jobs. For example, an IC can take a voltage input and output commands to a motor.
Terminology: Op-amp: - An operational amplifier (op-amp) is a set of transistors inside the integrated circuit. They often are the components doing the mathematical operations.
H-bridge: - An electronic circuit that enables voltage to be applied across a load in either direction. A DPDT switch also does this, but not electronically.
H-bridge
1. Need
four electronic switches.
2. Either
have 1 and 4 closed. Or 2 and 3 closed.
3. What
happens if both 1 and 2 are closed
4. The
H-bridge allows electricity to flow both ways across the motor, which gives us
forward and reverse.
5. We
can use pulse width modulation to control how often the switches are on versus
off, which gives us speed control.
Varying voltage
A potentiometer/variable resistor allows you to change the voltage input that goes into the integrated circuit.
Integrated circuit can now output variety of pulse widths to the transistors on the H-bridge.
This combination of potentiometer, integrated circuit and PWM to the H-bridge is the key to speed control.
Why not skip the IC?
There are a couple reasons we don’t use just a potentiometer to control the speed of our motors. Potentiometers are rarely used to control significant power (more than a watt). You would still need a way to switch the direction of the motor. Just using a potentiometer can control speed, but not direction. DPDT switch and potentiometer combinations can lead to problems if you quickly switch from full forward to full reverse. Problems can occur if the polarity of a spinning DC motor gets suddenly switched from forward to reverse. Current surge Mechanical stress.
Printed Circuit Board: - Components are attached to a printed circuit board. The ‘front’ side of the board will have printed component information, such as resistor # and resistance, diode type and polarity, etc. Holes go all the way through the board from one side to the other. Through hole
soldering is needed to connect components to the board.
Conclusion: -
Hopefully that wasn’t
too confusing. The goal was to give you a basic understanding of how some of
the electronic components of a motor speed controller work. There are lots of
tools to help you with the basics.
Next Topic will be mobile repairing tools and equipment's
