ELECTRONIC EQUIPMENT REPAIR : POLYTECHNIC EDITION

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

First Published Learning Module, 2022 © Wan Ghani Wan Pi, Rohaizan Saher & Mohd Nasran Mohd Nawi Session 2 2021/2022 All rights reserved. No part of this book (article, illustration and content) may be reproduced or used in any form or by any means, electronic or mechanical including photocopying, recording or otherwise without the prior permission of the author.

This Learning Module edition is published without any assessment or editing process. The quality of this edition will be improved from time based on feedbacks received from learning activities.

Perpustakaan Negara Malaysia

Data Pengkatalogan-dalam-Penerbitan

Rohaizan Saher ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION / Wan Ghani Wan Pi, Rohaizan Saher, Mohd Nasran Mohd Nawi ISBN 1. Electronic apparatus and appliances.

2. Electronic instruments.

3. Government publications--Malaysia.

I. Wan Ghani Wan Pi. II. Mohd Nasran Mohd Nawi III. Judul.

Published and printed by:

PREFACE

In the name of Allah, The Most Gracious and Merciful. All praise to Allah S.W.T. for His great loving kindness and blessing, this book successfully published.

With over 10 years of teaching experience in field of electrical engineering for the Malaysian polytechnic education system, the authors found that students lack the reading materials or reference that focused and in line with the requirements of the polytechnic's curriculum. According to the situation that is why the authors is trying to do their best to publish a book entitle "Electronic Equipment Repair Polytechnic Edition".

Although it is not as complete as any, but at least these small effort are able to enlighten the Malaysian polytechnic education system. This book is written primarily for students of polytechnic in Diploma of Electrical Engineering and perhaps it also might be used by others engineering student from another institution or maybe reference for electronic technician.

This book is designed to assist student in electronic equipment repair course according to the Electronic Equipment Repair (DEE30052) course syllabus for Diploma in Electronic Engineering (Communication) and Diploma in Electrical & Electronic student under the Department of Electrical Engineering at polytechnic in Malaysia. The authors would like to express deepest appreciation to all those who have provided the possibility in publishing this book especially friends and colleagues. Many thanks also go to the Electrical Engineering Department administration team for the support and guidance throughout the process of completing this book. Finally, our thanks to all friends who have contributed idea and support. Hopefully, student and lecturers can give feedbacks to improve the quality of this Electronic Equipment Repair Polytechnic Edition book. Thank you.

i.

ABSTRACT

This book is a necessity for Electronic Equipment Repair (DEE30052) course. It was written and produced specifically for third semester student of Electrical Engineering Department at Polytechnic Malaysia. Among the topics contained in the book are hand tools & soldering technic, test equipment, electronic component testing, power supply and electronic devices troubleshooting. This book has been prepared in accordance with chapter by DEE30052 course syllabus. This course focuses on the identification of faults in regulated dc power supply, audio equipment and television system. This course also provides knowledge and skills on troubleshooting and repairing broken cell phones.

ii.

CONTENTS TOPIC

PAGE

Preface

i

Abstract

ii

CHAPTER 1: HAND TOOLS & SOLDERING TECHNIC Introduction

1

1.1 Hand tools

1

1.2 Soldering Equipment

4

1.3 Technique Soldering

6

1.4 Soldering Process

6

1.5 The Ratio of Pb/lead in soldering

7

1.6 Type of lead

8

1.7 Soldering and de soldering station

9

CHAPTER 2: TEST EQUIPMENT Introduction

11

2.1 Multimeter

11

2.2 Oscilloscope

16

2.3 Capacitance Meter

18

2.4 Inductance Meter

19

2.5 ESR Meter

19

2.6 Transistor Tester

20

2.7 Signal Generator

21

2.8 Frequency Counter

22

2.9 DC Power Supply

23

CHAPTER 3: ELECTRONIC COMPONENT TESTING Introduction

25

3.1 Analyzing and fault finding techniques

25

3.2 Identify the terminal of component

34

CONTENTS TOPIC

PAGE

CHAPTER 4: POWER SUPPLY Introduction

39

4.1 Types of power supply

39

4.2 Linear dc power supply

39

4.3 Switching Mode Power Supply

48

CHAPTER 5: ELECTRONIC DEVICES TROUBLESHOOTING Introduction

51

5.1 Amplifier Classes

51

5.2 Audio amplifier block diagram

52

5.3 Faults at the power amplifiers

55

5.4 AM Radio

64

5.5 FM Radio

66

5.6 TV System

68

5.7 Basic Principle Cell phone works

71

REFERENCES

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

CHAPTER 1 : HAND TOOLS & SOLDERING TECHNIC 1.0 Introduction There is much more to tools for electronics than just screwdrivers and pliers. While most of the common tools can be found at a local hardware or home improvement store, many are unique to the electronics industry. These specialized tools have evolved over many years, in some cases starting out as modified versions of common hardware store types, and in other cases designed from the outset to fulfill a specific need.

One of the keys to successful in repairing is having he right tools to hand to help make the job easier and to do things in the best way possible. Obviously having he right soldering iron available is very important, but there are many other tools that can help make the job of soldering easier and enable the soldering that is done to be completed more easily and to a higher standard.

1.1

Hand tools

a.

Long-nose Plier

Long-nose plier is used for cutting and gripping, to bend, re-position and cut wire. Their long shape, they are useful for reaching into cavities where cables (or other materials) have become stuck or unreachable to fingers or other means.

Figure 1.1: Long nose plier b.

Plier

Plier is used for bending and compressing a wide range of materials and fitted with wire cutter blades either built into the jaws or on the handles just below the pivot.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Figure 1.2: Plier

c.

Side Cutter

Side cutter is used for cutting wire and cut off the source terminal.

Figure 1.3: Side cutter d.

Manual Wire Stripper

Manual wire stripper is a pair of opposing blades much like scissors or wire cutters. The addition of a center notch makes it easier to cut the insulation without cutting the wire.

This type of wire stripper is used by rotating it around the insulation while applying pressure in order to make a cut around the insulation. Since the insulation is not bonded to the wire, it then pulls easily off the end. This is the most versatile type of wire stripper.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Figure 1.4: Manual wire stripper e.

Tweezers

Tweezers is used for grip small objects such as wires and screws

Figure 1.5: Tweezers f.

Screwdriver

The screwdriver is used for tighten and loosen the screw. Turning the screw clockwise or counter-clockwise

Figure 1.6: Screwdrivers

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

1.2

Soldering Equipment

a.

Soldering Tools

A soldering iron/gun is a hand tool most commonly used in soldering. It supplies heat to melt the solder so that it can flow into the joint between two work pieces. For electronics work, a low-power iron, a power rating between 15 and 35 watts, is used.

Higher ratings are available, but do not run at higher temperature; instead there is more heat available for making soldered connections to things with large thermal capacity, for example, a metal chassis. Some irons are temperature-controlled, running at a fixed temperature in the same way as a soldering station, with higher power available for joints with large heat capacity. Simple irons run at an uncontrolled temperature determined by thermal equilibrium; when heating something large their temperature drops a little, possibly too much to melt solder.

Figure 1.7: Soldering iron A Soldering gun is an approximately pistol-shaped, electrically powered tool for soldering metals using tin-based solder to achieve a strong mechanical bond with good electrical contact. The tool has a trigger-style switch so it can be easily operated with one hand. Soldering guns are used where more heat is needed than from the lowerpower soldering irons. The temperature of the soldering tip is regulated manually by holding the button until the solder melts, and then releasing it. When the solder is about to start solidifying, the button is pressed again, and so on.

Figure 1.8: Soldering gun 4

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

b.

Desoldering Tools

Suction pumps are used to suck away molten solder, leaving previously joined terminals disconnected. They are primarily used to release through-hole connections from a PCB. The De soldering head must be designed so that the extracted solder does not solidify so as to obstruct it, or enter the pump, and can be removed and discarded easily. It is not possible to remove a multi-pin part by melting solder on the pins sequentially, as one joint will solidify as the next is melted; pumps and solder wick are among methods to remove solder from all joints, leaving the part free to be removed.

Figure 1.9: Solder sucker Desoldering wick or solder wick, is finely braided 18 to 42 AWG copper wire coated with rosin flux, usually supplied on a roll. The end of a length of braid is placed over the soldered connections of a component being removed. The connections are heated with a soldering iron until the solder melts and is wicked into the braid by capillary action.

The braid is removed while the solder is still molten, its used section cut off and discarded when cool. Short lengths of cut braid will prevent heat being carried away by the braid instead of heating the joint.

Figure 1.10: Solder wick

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

1.3

Technique Soldering

Soldering is a process by which you can join metal items together by applying heat along with special metallic alloys (solder) and allowing them to cool. This results in a metal bond between the metals that is strong and has good electrical conductivity under harsh mechanical environments Three requirements: i. ii. iii.

1.4

Low melting point metal (solder wire) Heat source (soldering iron) Flux (to clean the surfaces and prevent if from oxidizing)

Soldering Process i. ii. iii. iv. v. vi. vii.

Plug in and turn on iron Ensure iron is hot enough Melt a little solder and visually inspect how fast it melted Clean your tip on wet sponge to remove any oxidation, excess molten solder or debris on your iron Tin (apply a little solder) your iron. This is CRITICAL for good work Prepare your part for soldering Place your part in the PCB

Figure 1.11: Soldering process 6

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

a.

Inspect Your Bond i. ii. iii. iv.

b.

Good Soldered Joint i. ii. iii. iv.

c.

Cleanliness Temperature Time Adequate solder coverage

A list of things you don't want to do: i. ii. iii. iv.

1.5

Bond should be a cone and shiny Profile of bond should be concave, not convex Bond surrounds part completely…. not 99% Bond does not cover other connections – Smooth, Bright, Clean,Completely surrounded, Concave

Don't overheat the part or pad - Might damage your part or the pads/traces Don't under heat the part or pad - Creates poor bonds, cold joints Don't melt the solder on cold parts - Creates poor bonds, cold joints Don't use too much solder - Creates a mess, prevents inspection of good bonds and could 'bridge' or connect onto other parts .

The Ratio of Pb/lead in soldering

Tin/lead solders, also called soft solders, are commercially available with tin concentrations between 5% and 70% by weight. The greater the tin concentration, the greater the solder’s tensile and shear strengths. Alloys commonly used for electrical soldering are 60/40 Tin/lead (Sn/Pb) which melts at 183 °C (361 °F) and 63/37 Sn/Pb used principally in electrical/electronic work. The 63/37 is a eutectic alloy, which:  

has the lowest melting point (183 °C or 361 °F) of all the tin/lead alloys; and the melting point is truly a point — not a range..

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

1.6

Type of lead

a.

Tin-Lead solders  

b.

60% Tin, 40% Lead - solid at 361° F, liquid at 374° F 63% Tin, 37% Lead - eutectic point is 361° F No “pasty” range so joint movement less a problem as the solder nearly instantaneously goes from liquid to solid

Silver-bearing Solder 

c.

62% Tin, 36% Lead, 2 % Silver - solid at 354 ° F, liquid at 372 F Often used for surface mount components whose contacts contain trace amounts of silver. The use of lead in solder is now increasingly prohibited in many countries. Various "lead free" alloys are becoming popular and typically contain 97% tin, 2.5% silver and 0.5% copper.

These require higher soldering temperatures and do not "wet" as well as Lead-Tin alloy, as a result it requires more skill to produce a good quality solder joint.

Lead Free Solder and Composition (Pb-Free Solder) 



 

Lead free solder composition is different from composition of leaded solder. There is NO Lead (Pb) is Lead Free solder. Lead Free Solder is taking rapid momentum around the world after the EU (European Union) Directives to wipe off lead (Poison) from electronic soldering considering its health and environmental effects Many of the electronic companies and manufacturers around the globe were using Tin-Lead (Sn/Pb) solder (Solder Wire, Solder Bar, Solder Paste) for PCB assembly and rework / repairing. They also used No-Clean Liquid Flux and No-Clean Solder Paste. They did not bother to clean the PCB and the flux residue after assembly. These boards were later dumped into earth.

While Pb is dangerous and harmful during the assembly process, dumping the board in soil was harmful to the environment. This ultimately lead to make lead-free PCB assembly mandatory.

Best & Popular Lead Free Solder Composition o Lead Free Solder Wire – Sn96.5/Ag3.0/Cu0.5 o Lead-Free Solder Bar- Sn99.3/Cu0.7 o Lead-Free Solder Paste – Sn96.5/Ag3.0/Cu0.5

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

1.7

Soldering and de soldering station

Figure 1.12: Soldering & De soldering station

A soldering station is an electronic tool for hand soldering of electronic components onto a PCB. It consists of a station or a unit to control temperature and a soldering iron that can be attached to the station unit. Most soldering stations have temperature control and are mostly used in electronics PCB assembly and manufacturing units. They are also used for mass repairing of circuit boards. Most genuine service centers also use these temperatures controlled soldering stations for repair and rework jobs.

A soldering station can be either analog or digital. Analog units have knobs to control (increase or decrease) temperature. They don’t have any display to show the current set temperature. The temperature setting in these units is not very accurate.

They are good for jobs like mobile phone repairing.

On the other hand, digital units have settings to control the temperature digitally. They also have a digital display that shows the current set temperature. These units offer better accuracy and less tolerance but are little expensive than their analog counterparts.

You can easily make a soldering station that can be used for any type of work.

Though you need to make sure you follow the correct safety procedures. Soldering uses high temperatures and there is potential for splattering and other accidents. You also have concerns due to power and other issues to consider.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Soldering & De soldering Station Standard Operating Procedure (SOP): a.

Use Heatproof Materials

Soldering uses high heat as what you are doing is to create joints or joining different metals together. Basically you are melting a metal onto another wire or metal to create a connection. In order to do this, the tip of the iron will reach temperatures of about 400 degrees Celsius. So this can produce very serious burns if it should touch your skin.

You always want to put the soldering iron back on its stand as you can burn the table or workstation if you place it down on another surface, even if it is for a moment. Your safest procedure is to solder on a mat that is fire resistant. b.

Work in Ventilated Area

The fumes produced during soldering can be very irritating and it may not be enough to simply turn your head away from the fumes. Make sure you set up the soldering station in a well ventilated area and you may even need to set up a fan to get rid of the fumes.

You will need to set up the ventilation and air circulation to your preference. c.

Go for Regular Maintenance You want to make sure that the power cable does not wear out or become damaged.

You also want to make sure that the iron is properly grounded and that you turn it off whenever you are not using it. You also want to give the soldering iron its own electrical socket as overloading a socket can blow fuses or cause other safety issues. d.

Protect Your Eyes

It is a good idea to wear protective eyewear when soldering as there can be some splatter. You also should wear high heat resistant gloves if you need to hold anything into place. If you don’t have gloves, use needle nose pliers to hold things in place. If you are going to do a lot of soldering, then a heat resistant apron can also protect your clothing. e.

Wash Your Hands

You are supposing to wash your hands before eating and after using the bathroom and it is also important to wash your hands after soldering. Solder contains lead, which is toxic if it is absorbed through the skin or ingested somehow. You should make sure you wash your hands and workstation thoroughly to avoid a contamination or lead that may be present.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

CHAPTER 3: ELECTRONIC COMPONENT TESTING 3.

Introduction

Any component parts that are inter connected together to make a complete system have its own hierarchy. It is very essential for a computer technician or assistant engineer to know the systems hierarchy before works on the system as well as any electronics equipment.

Before troubleshooting is carried out, a few questions must be answer:i. ii. iii. iv.

3.1.

What type of equipment to be repaired What is the fault symptom of the equipment Do the equipment provides any schematic diagram What is the suitable technique is to be used.

Analyzing and fault finding techniques

To find fault for an electronic equipment, we must rely on it’s usage. Before finding fault, we should understand the basic function of the equipment. From then, we can analyze what is the fault or symptom. Every techniques used must be relevant to each other to prevent time-wasting.

The techniques can be line up as follows:i. ii. iii. iv. v. vi. a.

Symptom Finding Printed Circuit Tracing Signals Injections Voltage Measurement Resistance Measurement or Continuity Physical Fault Detection Symptom Finding

Every an equipment normally displays some symptom to give indication of the faults.

The troubleshooter must be well versed in the system and functions of the equipment in order to determine the fault. But for the users, they can only recognize a fault such as by the sound output of a radio either no sound, up normal sound etc. Below is the example of fault and functions for some equipment:-

25

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

1 2 3 4

Equipment Color TV Radio Oscilloscope Audio Generator

Symptom picture no color no sound no display no output

Table 3.1: System finding b.

Printed Circuit Tracing

Tracing through the printed circuit is essential to determine the location of the components and techniques to be used.

The most popular systematic fault location methods are:i. Determine the input and output ii. Determine the power source and earth iii. Determine the numbering of the components Printed circuit tracing can be done either from the input to output or vice-versa.

Below is an example of the printed circuit (pre amp printed circuit).

GND

Vcc

Figure 3.1: Pre amp printed circuit & with component label For a simple circuit such as audio amplifier, pre amplifier, tone circuit and etc, tracing the whole circuit is needed (pre amp printed circuit with component label).

26

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Vcc C1

R1

R4 C4

to switch selector

R2 C2 Q1

Mic

R7

R5

C5

C3

C6

R3

R6

Figure 3.2: Pre amplifier schematic diagram The components numbering on the printed circuit board indicate the beginning of the circuit, for example C1 and R1 is the first component in the circuit. The 1 st digits of the number represent the block grouping of the components. c.

Signal Injection

After isolating the fault area such as audio amplifier, signal injection and tracing is applied to this area. Function generator is one of the equipment that is used to inject signal to the isolated block. Oscilloscope is then used to trace the output signals of the circuits.

Follow this step before we begin the fault finding process:i. Identify the amplifier blocks ii. Identify the supply voltage to prevent from over-current. iii. Adjust a suitable signal of 1KHz or 400Hz from the function generator

27

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

5

RF, IF and Detector Volume

3

4

Pre Amplifier

Tone control

2

Driver Amp

Driver & Power Amp

Figure 3.3: Audio amplifier block diagram

iv. Check the speaker to determine whether it is functioning or not. It can be done by multimeter using X1Ω range.

Figure 3.4: Speaker Testing v. If the speaker is functioning, then signal can be injected at the input of power Amplifier

28

1

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Vcc

R9 C28 C7 R2

R5

R7 T7

T8 Q4

C4

R8

Q5

1nF

C2

R6

SPEAKER

C8

VR3

Q3 82u

R13 C13

R3

R4

D3

Rth

Figure 3.5: Push-Pull Amplifier Circuit

vi. If normal, place the audio generator probe at the driver input i.e before or after C2. Observe the output vii. If normal, check the tone circuit. The output will be small or the tone cannot be adjusted if this circuit is faulty.

R22 Vcc

C20 C12 R18

R20 C3

C4 VR1

from detector

to driver amp

R13

C1 Q1 VR2

R19

R21

C2

Figure 3.6: Pre-Amplifier Circuit

29

C13

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

viii. If the circuit is normal, inject signal at the pre-Amp input. Level the function generator to obtained an undistorted output signal.

d.

Voltage Measurement Technique

Once the fault area is located, voltage measuring technique is used. Supply voltage to this area must be determined. For example, a supply of +12V is available at the junction of R1 and R3. If lower or none, it meant the supply is not normal.

If the supply voltage is normal, voltage must be measured around the active component i.e transistor Q1. +12V C20 R18

R20 C3 Output

C1

Vb

Vc Vdc

Q1 Input

Multimeter _ +

Ve R19

R21

C2

Figure 3.7: Amplifier circuit To analyze the measured voltage, we have to know the normal voltage value for the circuit. For example:Collector Voltage (Vc) = 5.5V Base Voltage ( VB) = 2.5V Emitter Voltage (VE) = 1.7V Then we can analyze the faulty area and determine the fault.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

Example 1 If Vc = 0.1V, which component faulty and what is the fault?

Answer: R3 open-circuit (no supply to the collector) Example 2 If Vc = 11.8V, what is the fault?

Answer: i. R1 open-circuit or ii. CE Q1 open or iii. R4 open Example 3 If VB

=

0.1V

Answer: i. BE Q1 shorted or ii. R1 open Example 4 If VE

= 0V

Answer: i. C2 shorted or ii. E Q1 open

e.

Resistance Measurement Technique

The resistance measurement technique can be measured outside from the circuit. The power supply must be ‘OFF’. This method is used for components with known resistance such as resistor, diodes, transistors etc. i.

Resistor Resistor can be measured in the circuit with the lower of resistance. The resistor givesan infinity or higher resistance when resistor is in open circuit.

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

ii. Fuse The suitable ohm range for checking continuity of fuse is X1Ω. If the resistance is low, the fuse is normal but if the resistance is infinity or high value, the fuse is blow. iii. Inductor A normal inductor, the resistance of is low. The suitable ohm range of multimeter is X1Ω. If the resistance of inductor is 0 Ohm when used x1Ω range, the inductor is shorted. When the resistance of inductor infinity or high value (use X10KΩ range), the inductor in open circuit. iv. Transformer The continuity or resistance of transformer primary and secondary coil is low when using X1Ω range. If the resistance is 0Ω (X1Ω range), the coil is shorted. If the resistance is infinity (X10KΩ range), the coil is opened circuit.

Secondary

Primary

Coil/inductor

Figure 3.8: Transformer v. Relay The two terminal of relay is coil or inductor. The resistance of coil is low when using X1Ω range. If the resistance is 0Ω (X1Ω range), the coil is shorted. If the resistance is infinity (X10KΩ range), the coil is opened circuit. NC is normally close. NO is normally open.

Figure 3.9: Relay

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

vi. Switch A simple ON-OFF switch, the two terminals are either connected together or disconnected from each other. The suitable range of ohm range to check continuity between two terminals of switch is X1Ω. If the resistance is 0Ω, the switch is connected. If the resistance is infinity, the switch is disconnected

Figure 3.10: Switch Symbol

vii. Diode and zener diode The same applied to measuring diode which including checking on it’s biasing. If diode is forward bias the resistance is low and if diode is reverse bias the resistance is infinity or high. If the resistance of diode is 0 Ohm when used x1Ω range, the diode is shorted. viii. Bipolar Transistor A normal transistor, the resistance of Base-Collector and Base-Emitter is low. If the resistance of Base-Collector and Base-Emitter is 0 Ohm when used x1Ω range, the transistor is shorted. If the resistance of Base-Collector and BaseEmitter is infinity or high Ohm when used x10KΩ range, the transistor is opened. ix. Silicon Control Rectifier (SCR) or Thyristor The thyristor or silicon control rectifier, SCR is a device that has a number of unusual characteristics. It has three terminals: Anode, cathode and gate, reflecting thermionic valve / vacuum tube technology. As might be expected the gate is the control terminal while the main current flows between the anode and cathode.

Figure 3.11: SCR Symbol The resistance measurement of SCR is the same like the resistance of diode. The forward bias between terminals Anode – Cathode is low resistance 33

ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

using X1Ω range. If the resistance is 0 Ω, the thyristor is shorted. The reverse bias between terminals Anode – Cathode is infinity or high using X10KΩ range. f.

Fault Finding by Physical Technique

It involves a few senses such as visual observation, hearing, smell and taste or touch. i. Visual Observation By observation, we can locate the faulty area such as burning trace, loose connection, broken etc. ii. Hearing and Smelling Sometimes a burnt or spark cannot be seen but can be heard or smelt. For example, a high voltage transformer normally gives sparks if its insulation cracked or his sound, or else yield the burning smell if over heated. iii. Taste This method only applied to fault such as broken components, dry joints, dislodge and etc.

3.2. i.

Identify the terminal of component Diode

Figure 3.12: Diode

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

ii. Bipolar transistor

Figure 3.13: Bipolar transistor

iii. Silicon Control Rectifier (SCR)

Figure 3.14: Bipolar transistor

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

iv. Uni Junction Transistor (UJT)

Figure 3.15: Uni junction transistor

v. Field Effect Transistor (FET)

Figure 3.16: Field effect transistor vi. Diac

Figure 3.17: Diac

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

vii. Triac

Figure 3.18: Triac viii. Integrated Circuit (IC)

Figure 3.19: Integrated circuit

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THIS PAGE IS INTENTIONALLY LEFT BLANK

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ELECTRONIC EQUIPMENT REPAIR POLYTECHNIC EDITION

References

David A. Bell, (2008). Electronic Devices and Circuits ( 5th Ed ). Oxford F. F. Mazda, (1997). Electronics Engineer's Reference Book (6th Ed ). Newnes; 6th Edition Millman, Jacob. (2015). Millman's Electronic Devices and Circuits (SIE) , 4th Edition Paperback. McGraw Hill Education.

Simon M. Sze (Author), Kwok K. Ng (Author), (2006). Physics of Semiconductor Devices (3rd Ed). Wiley-Interscience Poole, Ian. (Author). Electronics Notes. From http://www.radio-electronics.com ; May 2019 Resources for Repair Guides Note. From http://www.ifixit.com : May 2019 Lenk, John D (1999). Circuit Troubleshooting Handbook. New York: McGraw-Hill.

Grob, Bernard (2003). Basic Electronics. New York: Glencoe McGraw-Hill