DEE 30052 ELECTRONIC EQUIPMENT REPAIR
PRACTICAL WORK: 5
TITLE: LED COLOUR TELEVISYEN
1.0 LEARNING OUTCOMES(LO):
CLO1: diagnose fault of electronic equipment related to electronic equipment repair
using the correct diagnosis technique and tools (C4, PLO2)
CLO2: fix the post-consumer’s electronic equipment fault using the correct diagnosis
technique (P4, PLO5)
CLO3: demonstrate good social responsibility in solving well defined engineering
problems during performing electronic system and appliances maintenance task
(A3, PLO6)
2.0 OBJECTIVES
At the end of the session, the students will be able to:
1. Identify the functional of LED colour TV
2. Detect failure symptom of LED TV parts
3. Measure the voltage value of faulty LED TV parts
3.0 EQUIPMENTS/TOOLS
1. LED TV Trainer
2. Multimeter
3. Oscilloscope
4.0 THEORY
LED Colour TV
LED (Light Emitting Diode) TVs are basically LCD TVs that use a LED backlight
system to illuminate the LCD screen. There are two methods to accomplish this:
1. LED edge lighting (Edge lit): In this method, LED lights are placed around the
perimeter (sides) only. This allows for a slimmer TV design.
2. LED Backlight (Array lit): In this method, LED lights are placed in the form of an
array (across the whole back of the display). Any of the lights can be turned off to
correspond with the scene being displayed, and this is why it can project such an accurate
picture.
LED Backlight (Array lit): In this method, LED lights are placed in the form of an
array (across the whole back of the display). Any of the lights can be turned off to
correspond with the scene being displayed, and this is why it can project such an accurate
picture.
1
LED TVs will produce deeper blacks due to “local dimming” technology. In
comparison, LCD TVs produce a lower picture quality, especially when projecting dark
backgrounds. The Cold Cathode Fluorescent Lamp (CCFL), which is located behind the
screen, does not actually remain cool. Instead of using all of its energy to produce light,
it wastes energy in the form of heat. Further, since the CCFL current flow must be kept
at a high level to preserve its lifespan, LCD screens cannot be easily dimmed. This is
one of the reasons why LED TVs can operate more efficiently while providing a more
precise image quality
Currently LEDs are not small enough to be used for individual pixels in domestic
televisions, and so the use of true LED TVs is restricted to much larger screens in places
such as sport stadia. Don't let this put you off however, as there are some great benefits
to choosing an LED TV over a standard LCD TV.
1. Improved brightness and contrast levels, with deeper blacks.
2. The use of Edge-LED lighting allows the TV to be thinner than standard LCD TVs.
3. LED TVs can consume up to 40% less power than a LCD TV of similar size.
4. They can offer a wider colour gamut, especially when RGB-LED backlighting is
used.
2
Main Board ( Haeir LE24T1000F)
To
backlight
LED
AP3039
(N-channel MOSFET)
TDA1517P
To LCD screen
(Sound)
MDS3652
To speaker
(P-channel MOSFET)
25Q32BS1G
(Flash Memory) RT7257EN
MST6M182VG (Step-down
(CPU/MCU) converter)
TP6
TP10 TP9
TP8
TP2
TP5
TP1
TP4
TP7
TP3
3
5.0 PROCEDURE :
Normal Condition
1. Switch On the LED TV Trainer and observe the TV condition such as display and
audio signal.
2. Measure and record normal voltage at each test point using multimeter. (Fulfill all
measurent data in Table 2.)
Table 1: VoltageTest Point
Test Point Parts
AC Test Point Power Supply
TP1 Adjustable Precision shunt Regulator (TL4311)-PIN Ref
TP2 Adjustable Precision Shunt Regulator (TL4311)-PIN Cathode
TP3 Power Schottky Rectifier (MBR201000FCT)-PIN Cathode
TP4 Backlight LED Voltage
TP5 Input LCD (Orange)
TP6 Input LCD (Red)
TP7 Remote Control Input Voltage
TP8 12 Volt Input Voltage
TP9 5 Volt Input Voltage
TP10 Sound IC (TDA1517P)-PIN 7
Power supply Failure Condition
1. Switch On the LED TV Trainer and select switch FAULT 1 at the main panel unit.
2. Measure and record the voltage at each test point using multimeter. (Fulfill all
measurent data in Table 2.)
Backlight Failure Condition
1. Switch On the LED TV Trainer and select switch FAULT 2 at the main panel unit.
2. Measure and record the voltage at each test point using multimeter. (Fulfill all
measurent data in Table 2.)
LCD Failure Condition
1. Switch On the LED TV Trainer and select switch FAULT 3 at the main panel unit.
2. Measure and record the voltage at each test point using multimeter. (Fulfill all
measurent data in Table 2.)
Audio Failure Condition
1. Switch On the LED TV Trainer and select switch FAULT 4 at the main panel unit.
2. Measure and record the voltage at each test point using multimeter. (Fulfill all
measurent data in Table 2.)
4
6.0 RESULT
Table 2: Voltage Test Point
TEST NORMAL Fault 1 Fault 2 Fault 3 Fault 4
POINT CONDITION (Volt) (Volt) (Volt) (Volt)
(Volt)
AC Test Point
TP1
TP2
TP3
TP4
TP5
TP6
TP7
TP8
TP9
TP10
( 55Marks )
5
Please state your observation and type of failure in Table 3 bellow.
Table 3: Type of Failure
Selector Observation and Fault Description
Switch
Fault 1
(3Marks)
Fault 2
(4Marks)
Fault 3
(4Marks)
Fault 4
(4Marks)
6
8.0 DISCUSSION (5Marks)
9.0 CONCLUSION (5Marks)
Give your conclusion about the result obtain in Table 2 and Table 3.
