Mobile Phone Repair

Topics: Mobile phone, Logic gate, Semiconductor Pages: 8 (1555 words) Published: February 25, 2013
This Presentation Contains Demo Slides of the Mobile Repairing Course

Electricity - What is it?

 General definition of electricity

 Electricity is a general term that refers to a variety of phenomena resulting from  The presence electrons.

 Flow of electric charge.

Generation of Electricity

• Electric current generation - whether from fossil fuels, nuclear, renewable fuels, or other sources is usually based on the:

Introduction to diode

– A diode is the simplest possible semiconductor device, A diode allows current to flow in one direction but not the other. You may have seen turnstiles at a stadium or a subway station that let people go through in only one direction. A diode is a one-way turnstile for electrons. – When you put N-type and P-type silicon together as shown in this diagram, you get a very interesting phenomenon that gives a diode its unique properties.

– Even though N-type silicon by itself is a conductor, and P-type silicon by itself is also a conductor, the combination shown in the diagram does not conduct any electricity. The negative electrons in the N-type silicon get attracted to the positive terminal of the battery. The positive holes in the Ptype silicon get attracted to the negative terminal of the battery. No current flows across the junction because the holes and the electrons are each moving in the wrong direction.

Frequency Modulation (FM)

Simple Basic Digital Logic Gates

– Simple digital logic gates can be made by combining transistors, diodes and resistors. – Example of a Diode-Resistor Logic (DRL) AND gate and a Diode Transistor Logic (DTL) NAND gate.

Uses of Oscilloscopes

– Oscilloscopes are commonly used to observe the exact wave shape of an electrical signal. – In addition to the amplitude of the signal, an oscilloscope can show distortion, the time between two events and relative timing of two related signals. – Oscilloscopes are used in the sciences, medicine, engineering, and telecommunications industry.

GSM Architecture Layout

CDMA Spreading

Printed Circuit Board (PCB)

The circuit board is the heart of the system. Here is one from a typical Nokia digital phone:

The front of the circuit board The back of the circuit board

Architecture of GPRS network

Introduction to Wi-Fi

• It is the best alternate for broadband connectivity in homes, offices, and public hotspot locations. • Systems can provide a coverage range of about 1,000 feet from the access point.

• Wi-Fi offers higher data rates than 3G systems as it operates on 20MHz bandwidth. • Now a days Wi-Fi is used in variety of devices, including personal data assistants (PDAs), cordless phones, cellular phones, cameras, and media players.

The GPS satellite system

– 24 satellites that make up the GPS space segment.
– GPS satellites are powered by solar energy.

– Orbiting the earth about 12,000 miles above us.
– Making two complete orbits in less than 24 hours. – Satellites are travelling at speeds of roughly 7,000 miles an hour.

Basic operational Block Diagram

Hence the basic operational methods of a Cell-phone have three sections . – Radio Frequency (RF Section) – The Analog Baseband Processor

– The Digital Baseband Processor.

Step 4

– Unscrew six pieces fixed bolt of front panel with T6 X 50mm or A5 screwdriver.

Procedures to remove SMD Component

Use a Tweezers to hold the component and observed until the solder joint is melted.

Slowly pull in upward direction, when solders melts. Do not pull upward forcibly when the solder is not melted.

ESDS – Electrostatic Discharge Sensitive

– Type of parts which are ESD Sensitive
• • • • Integrated Circuits (DIPs, QFP, BGA, SOT, etc.) Crystals and oscillators Printed Circuit Board Assemblies When in doubt, treat it as ESDS!

Logic control section circuit Diagram
D300 C.P.U.

1 N400 Interface 9 IC 13


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