TV REPAIR AND TROUBLESHOOTING GENERAL BASIC GUIDE

 Common LCD TV Repair problems
There are many types of TVs and each TV requires different type of repair. TV repair service centres faces different Types of problem in daily life. Service centers have experienced TV technician who know how to fix the problem. Here we are going to discuss some common TV repair problems come in TV Repair Service Center.

 1. Back light is shown in LCD TVs but no picture is shown.

2. LCD TVs turn off but led lights continuously blinking.

3. TV do not show any image. It could be due to damaged IC's on buffer board or bad y-sustain board.
 

4. Horizontal and verticals lines shown in TV.

5. If your TV is not working than unplug all the wires from the TV For few minutes. This trick works many times.

6. Some Times TV parts have some burn holes, smell like burning, cracks on outside parts. This could be a major issue but sometimes it is only due to burning of flux, When device heats, flux melts.

7. Damaged or Broken TV Screens.
When TV Screen is damaged or broken then first question arise in our mind is that broken TV screen could be repaired or not.

Precautions: If you are trying to repair your TV at home always remember to wear gloves that decreases the risk of Electric shock. But mainly you have to go to TV repair service centre for repairing your TV. Because they know what is the exact problem and how to fix it. And second thing is they have all the necessary part available. You can call your TV technician at your home for their advise.

Problems that really ask for TV Repair:

 In today’s  market, LCD’s and LED’s are the most common available Television segment. Thus in this topic we will consider LCD & LED. Where we will discuss about problem’s which need TV Repair service. And their estimated solutions. Here, we will provide information based on surveys and research. Actual solution may vary much.

  



Back-light Issue: The most common and happening problem of LED’s these days. In this issue, the back-lighting operation of LED TV doesn’t work properly. It tends to make several screen and display issue. Its quite common in every LED screens these days. And usual to repair as well. But the reasons are not that common, the problem may occur for many reasons. Sometimes due to mishandling, due to electric fluctuation, rebooting frequently and many more like led overdriving to obtain high light levels, bad hardware design and poor engieering and manufacturing......... But the symptoms stay same.

  


PCB MAINBOARD (Printed Circuit Board): PCB is basically known as Main Board of Television. In other words, it is Mother board of any Television set. It controls complete functionality of Television. It is programmed in order to control total supply of input & output. It is of video, audio, VGA, graphics, color, multimedia, processing, cooling, connectivity, power, software operation, networking & core memory. Hence, it is main system operator of any Television. Thus any problem related to input & output of above mentioned operations. Directly relate of PCB failure. Which implies it is either dead or irrationally got shot by circuit media.




   SMPS ( Switch Mode Power Supply):Commonly known as power supply and Inverter board. SMPS is an electronic power supply that incorporates a switching regulator, In order to convert electrical power efficiently & effectively. Like other power supplies, an SMPS transfers power from a DC or AC source (often mains power) to DC loads. Much like as in a personal computer, while converting voltage and current structure. Unlike a linear power supply. The pass transistor of a switching-mode supply continually switches between low-dissipation. Full-on and full-off states. And wastes very little time in the high dissipation transitions. Which reduce wasted energy. SMPS failure directly turns the Television into dead mode. No power supply, hence it doesn’t even turn on.



T-Con Board :- T-Con board refers to timing control board. It basically does all video controlling operations. This board controls whole functionality of display screen. It converts video electric signal from lvds Mainboard PCB to display module language. Which display back-lit system understands & behaves as directed. Back-lit operations are directly supported & coordinated by T-Con Board itself. Hence, if anything goes wrong with display picture portion. Backlight area & screening portion. It points that there might be any T-Con board failure !

 

 

The LCD Display Panel :Flat-panel displays are electronic screening system. Used to enable people to see contents with still images, moving images, text, or other visual material. With quality in a range of varieties of shapes and sizes. They are far lighter and thinner than traditional cathode ray tube (CRT) television sets. And video displays and are usually less than 10 centimetres (3.9 in) thick. They came up in order from Ordinary, HD Ready, Full HD, Ultra HD (4K), Curve OLED and 3D. Any problem related to display screen misbehavior. Is directly associated with display panel. But may or may not be associated with T-Con board.

 

 

 

 Sensors Issue : Sensor is basically known as the infrared adapter. Which controls wireless connectivity with remote. It functions as a controlling body. Which receives digital wireless signals from remote & performs as directed. It actually controls all basic features. Which are present in remote. Thus, any malfunction in sensor board, makes TV go crazy. Audio, input, channel router, buttons, video and everything starts misbehaving.

 

 

 

 Button Faults :Button’s are usually a included control segment of Television. It have some basic units of control, like power,volume,channel,input & enter. It usually works with a small circuit board. Connected via sensor board. But sometimes buttons got pressed or damaged. Its a common fault caused by mishandling. 

 

 

LCD Panel Broken :Flat panels are the most vital part of Television & most sensitive too. They are the display screens which allows you to view motion pictures into it. It costs 80% of total value of Television.

 

 

 

 

 Software / Firmare Issue :Software represents operating system of Television. Like, Windows or LINUX in Computers. There are several software developed by manufacturing companies. Which is stored in Master IC of PCB Board. It allows you to operate complete Television function. Sometimes due to external bleach or virus, it got damage. At that point, software issue comes. It start misbehaving, flickering and stand-by, by default.Many if not all Tv are using a LINUX Kernel !

 

 

Solutions for TV Repair:

 Back-light issue : Backlight issue can be repaired by replacing the back-lit LED strip set. When an back-lit issue encounter’s, it direct tend to fuse back-lit LED bulbs. Thus the first and foremost step is to replace back-lit strips connected with LED bulbs. After that, we need to inspect what is the reason behind this back-lit failure. The most happening reason used to be, T-Con Board malfunction or rapid wear of leds due to poor engineering and manufacturing or even misuse of hi bright. If its a T-Con board problem, then  companies recommends to change T-Con board. Otherwise, it may effect Display panel. Thus, basically complete back-light issue solution is to replace T-Con board and LED strips at the same time.

 

 

PCB / MAINBOARD Issue (Printed Circuit Board):PCB refers to Main Controller Board or Motherboard technically. Thus any problem occurred in PCB can turn a complete Television into disaster. PCB’s comprises of many micro components. And every component is designed & programmed to do different job’s. If any one component from PCB becomes isolated, it may effect the complete functionality. And as per company directions, PCB always recommended to replace. As and when encountered any issue. Otherwise, it can generate opposite power supply. Which can damage whole Television. Hence, its preferred to replace PCB every-time.

 

 

 

SMPS POWER SUPPLY  Issue ( Switch Mode Power Supply):SMPS  regulates main power supply system in a programmed way. But sometimes, due to electric fluctuation. High voltage supply & home electric supply malfunction. SMPS used to break down. And there are three ways of breaking down. The first one is, due to limited high power supply, fuse become detached. Here, changing of fuse can recover SMPS easily. Second way is where, due to abnormal power supply. Some SMPS components get shot. Here, changing of those components can recover SMPS again. The most worst case is when, due to high un-grounded lighting direct power supply. SMPS get burned. In this case, complete SMPS board need to be changed. And at the same time it might have harmed PCB / MAIN too. Its complete unpredictable. 

 

 

T-Con Board Issue : T-Con board operates complete back-lighting system in order to quality screening performance. It used to be connected with panel X-Boards. T-Con Board issue basically happens along with back-lit breakdowns or from X-board failure. T-Con board is also a printed circuit board. Thus it is not recommended to be repaired. Hence, it’s need to be replaced for safety of display panel. And continuity of viewing quality.

 

 

Display Panel Issue :Panel is the screening system. Thus it is the most dedicated part of any Television set. Display panel acquires 80% value of the total TV. And honestly saying, no company repair display panels. According to recommended directions by LED TV Panel Repair. Display panels should not be repaired. Hence it hikes up television sale, once it is in need of repairs. Even we were not into display panel repairs before. But we started doing this after heavy request from customers. Display panels may damaged from many ways, but only few of them are repairable. Anyway it can be repaired. But it need to pass from bonding process then X-boards need to be replaced. By doing this, display panels can be repaired. But excluding water damage.

 

 

Sensors Issue : We have discussed before, sensor plays a very vital role in Television functionality. But in case of sensor malfunction. It can be repaired easily. By simply changing some defective components in sensor board. But recommended, TV remote should also be changed with sensor board. 

 

 

 

 Button Faults :Buttons have the key role in operation of any Television. Thus it need to be in working condition anytime. Thus, in case buttons are damaged & need repairs. Yes, it is possible and in very simple way. Just by replacing button panel which is connected with sensor board. In case due to button faults sensor board is damaged. Then it can also be replaced along with that.

 

 

LCD Panel Broken : Display panel is the most vital & dedicated part of any Television. As we have discussed before. Its quite difficult to repair display panels. And even not recommended by manufacturers. But as it holds 80% of total value. Thus  fix some possible display repair requirements. But in case display panel is broken. Trust me there is no other option of fixing it up. You can better go for new TV instead. As suggested by TV Panel Repair.

 

 

 

Software / FIRMWARE  Issue : As already we have discussed about software issue. Which creates malfunction in operating system. And its a common issue in Television’s nowadays. Because of high performing crap in markets firmwares are deleting themselves by crappy hardware design. But not to worry about it. Software can be reloaded through external up-loader. But in case, it has caused some permanent damages in Master/System IC. Then for TV’s fortune, PCB need to be replaced

HOW A 2-STROKE ENGINE WORKS – PRINCIPLE AND TROUBLESHOOTING

How a 2-stroke Engine works – Principle - Troubleshooting

The 2-Stroke Internal Combustion Engine Troubleshooting

A two-stroke cycle or “two-cycle” engine produces one power stroke for every revolution of its crankshaft. Intake and compression occur during the piston’s “up” stroke; power and exhaust occur during the “down” stroke.  Six distinct processes occur during every revolution of the crankshaft, and a loss or weakness of even one of these processes will affect the other five.

Piston Ported Induction
1. Intake
As the piston moves up toward the cylinder head, a low pressure (vacuum) is created in the crankcase. As the moving piston uncovers the intake port, atmospheric pressure pushes a fresh charge of fuel-air mixture into the crankcase.  The mixture accomplishes two functions before it is moved to the combustion chamber:
■ Oil suspended in the mixture coats all internal engine parts including cylinder walls, crankshaft, and bearings.
■ The atomized fuel mixture absorbs heat as it enters the crankcase, lowering the engine’s operating temperature.
2. Compression
As the piston continues to move upward and cover the cylinder ports, the combustion chamber is sealed and compression begins.  The air-fuel mixture introduced during the previous revolution’s transfer cycle is now trapped and becomes compressed between the piston and cylinder head.

3. Ignition
As the piston approaches the top of the cylinder, the spark plug fires and ignites the fuel-air mixture. To compensate for increases in engine rpm, spark timing is advanced electronically.

4. Power (combustion)

The fuel-air mixture expands rapidly as it burns, forcing the piston down the cylinder.  Piston movement is transferred to the crankshaft through the connecting rod, rotating the crankshaft.
5. Exhaust
Expanding gasses continue to force the piston downward, exposing the exhaust port. Most of the spent combustion gasses are expelled through the exhaust port.
6. Transfer
The piston’s downward movement covers the intake port and uncovers the transfer port, while simultaneously compressing the fresh fuel-air mixture drawn into the crankcase during Step 1. As the transfer port is uncovered, the fresh mixture swirls rapidly into the cylinder.

As the fresh fuel-air mixture enters the cylinder, it also helps to push or scavenge any remaining exhaust gasses out through the exhaust port.

The burning mixture expands, forcing the piston down and compressing the fresh mixture in the crankcase. As the piston exposes the transfer port, crankcase pressure forces fresh mixture into the combustion chamber and helps push the remaining exhaust gasses through the exhaust port.

1.Intake

As the piston moves up toward the cylinder head, low pressure (vacuum) created in the crankcase allows atmospheric pressure to open the reed valve and push a fresh charge of fuel-air mixture into the crankcase.  The fuel-air mixture accomplishes two functions before it is moved to the combustion chamber:
■ Oil suspended in the mixture coats all internal engine parts including cylinder walls, crankshaft, and bearings.
■ The atomized fuel mixture absorbs heat from the crankcase, lowering the engine’s operating temperature.

2.Compression
As the piston continues to move upward and cover the cylinder ports, the combustion chamber is sealed and compression begins.  The air-fuel mixture introduced during the previous revolution’s transfer cycle is now trapped and becomes compressed between the piston and cylinder head.
3. Ignition
As the piston approaches the cylinder head, the spark plug fires and ignites the fuel-air mixture. To compensate for increases in engine rpm, spark timing is advanced electronically.

Reed Valve Induction System (reed valve open)

4. Power (combustion)
The fuel-air mixture expands rapidly as it burns, forcing the piston down the cylinder.  Piston movement is transferred to the crankshaft through the connecting rod, rotating the crankshaft.
5. Exhaust
Expanding gasses continue to force the piston downward, exposing the exhaust port. Most of the spent combustion gasses are expelled through the exhaust port.
6. Transfer
The piston’s downward movement compresses the fuel-air mixture drawn into the crankcase during Step 1, causing the reed valve to close. As the moving piston uncovers the transfer port, the fresh mixture swirls rapidly into the cylinder.  As the fresh fuel-air mixture enters the cylinder, it also helps to push or scavenge any remaining exhaust gasses out through the exhaust port.

Troubleshooting

Mechanical failure of any carburetor is far less common than problems arising from contaminated fuel, improper adjustment, or operator abuse.  Carburetor operation is directly affected by the quality of air and fuel entering the carburetor! Before troubleshooting or adjusting any carburetor, inspect fuel and air filters for cleanliness, operation, and proper installation.

1.Is the fuel tank filled with clean, fresh fuel of the proper grade and mixture?
2. Check for spark.
3. Compression at least 100 psi or above?
4. Is the air filter clean and properly installed?

5. Are the spark arrestor and muffler clean and properly installed?
6. Inspect fuel filter, and check fuel lines for leaks/deterioration. Pressure-test fuel system for leaks.
7. Inspect the impulse tube or passage for condition and operation. Pressure-test crankcase as required.

8. Inspect the tank vent. Clean or replace as required
9. Reset carburetor mixture adjustments.
10. Pressure test the carburetor for pop-off and reseat values.

What are the differences between a 2-stroke and a 4-stroke engine?

Answer Wiki

There are nearly 100+ answers to this question.

This is the Consolidation of the more salient points.

Number of strokes per power stroke.

• 4 strokes have a total of 4, 2 of upstroke, then 2 of downstroke in a vertical engine.
• 2 strokes only need 1 combination exhaust, intake, to have a power stroke.

Oil Mixing

Since a two stroke has no direct crankcase lubrication, it has a higher requirement for having the oil added with the fuel*.

The Four stroke engine has a separate compartment for the crankcase oil, and an oiling system to keep everything lubricated.

(*) exception, is with diesel locomotives, they have a diesel injector that self lubricates the pistons, so it can have a separate crankcase and lubrication system.

100+ Answers

 What is the difference between a 2-stroke and a 4-stroke engine?

Difference between a 2-Stroke and a 4-Stroke Engine are:

2- Stroke Engine : It has one revolution of crankshaft within one power stroke.

4-Stroke Engine: It has two revolution of crankshaft between one power strokes.

2.

2- Stroke Engine : It can generate high torque compare to 4 strokes engine.

4- Stroke Engine: It generates less torque due to 2 revolution of crankshaft between one power strokes.

3.

2-Stroke Engine : It used port to inlet and outlet of fuel.

4- Stroke Engine : It used valve to inlet and outlet.

4.

2- Stroke Engine :2 stroke engines require lighter flywheel compare to other engines because it generates more balanced force due to one revolution for one power stroke.

4-Stroke Engine : It requires heavy flywheel because it generates unbalance force due to two revolutions for one power stroke.

5.

2- Stroke Engine :The charge is partially burn and mix with the burn gases during inlet. It is due to port mechanism.

4-Stroke Engine : In four stroke engine charge is fully burn and does not mix with burn charge in ideal condition.

6.

2- Stroke Engine : Easy lubrication due to lubrication oil mix with the fuel.

4-Stroke Engine : Comparatively complicated lubrication.

7.

2- Stroke Engine : More lubricating oil requires because some oil burns with fuel.

4-Stroke Engine : Comparatively less lubricating oil requires.

8.

2-Stroke Engine : These engines give less thermal efficiency.

4-Stroke Engine : These engines give more thermal efficiency.

9.

2-Stroke Engine : It has high power to weight ratio compare to others.

4-Stroke Engine : 4 stroke engines have less power to weight ratio.

10.

2- Stroke Engine : It creates more noise.

4- Stroke Engine : It is less noisy.

11.

Two stroke engines are less efficient and generate more smoke.

Four stroke engines are more efficient and generate less smoke.

12.

2-Stroke Engine : These engines are comparatively cheaper.

4- Stroke Engine : These engines are expansive due to valve and lubrication mechanism.

13.

2-Stroke Engine : These engines are easy to manufacture.

4-Stroke Engine : These engines are comparatively hard to manufacture.

14.

2-Stroke Engine : These engines are generally lighter.

4-Stroke Engine : These engines are comparatively heavier than 2 strokes due to heavy flywheel and valve mechanism.

15.

2-Stroke Engine : These are mostly used in ships, scooters etc.

4- Stroke Engine : These engines mostly used in car, truck, and other automobiles.

16.

2- Stroke Engine : Due to poor lubrication more wear and tear occurs

4- Stroke Engine : Less wear and tear occurs.

These are the differences between 2 stroke and 4 stroke engine.

(Image source: Google)

POINTS OF ATTENTION IN SERVICING OF LCD TVS

POINTS OF ATTENTION IN SERVICING OF LCD TVs

• Be sure to switch off the power supply before replacing or welding any components or inserting/plugging in connection wire Anti static measures to be taken (throughout the entire production process!):
• Do not touch here and there by hand at will;
• Be sure to use anti static electric iron;
• It’s a must for the welder to wear anti static gloves.
• Refer to the detailed list before replacing components that have special safety requirements. Do not change the specs and type at will.

• Screens are different from one model to another and therefore not interchangeable. Be sure to use the screen of the original model for replacement.
• The operation voltage of LCD screen is 700-825V. Be sure to take proper measures in protecting yourself and the machine when testing the system in the course of normal operation or right after the power is switched off. Please do not touch the circuit or the metal part of the module that is in operation mode. Relevant operation is possible only one minute after the power is switched off.
• Do not use any adapter that is not identical with the TV set. Otherwise it will cause fire or damage to the set.
• Never operate the set or do any installation work in bad environment such as wet bathroom, laundry, kitchen, or nearby fire source, heating equipment and devices or exposure to sunlight etc. Otherwise bad effect will result.
• If any foreign substance such as water, liquid, metal slices or other matters happens to fall into the module, be sure to cut the power off immediately and do not move anything on the module lest it should cause fire or electric shock due to contact with the high voltage or short circuit.
• Should there be smoke, abnormal smell or sound from the module, please shut the power off at once. Likewise, if the screen is not working after the power is on or in the course of operation, the power must be cut off immediately and no more operation is allowed under the same condition.
• Do not pull out or plug in the connection wire when the module is in operation or just after the power is off because in this case relatively high voltage still remains in the capacitor of the driving circuit. Please wait at least one minute before the pulling out or plugging in the connection wire.
• When operating or installing LCD please don’t subject the LCD components to bending, twisting or extrusion, collision lest mishap should result.
•  As most of the circuitry in LCD TV set is composed of CMOS integrated circuits, it’s necessary to pay attention to anti static. Before servicing LCD TV make sure to take anti static measure and ensure full grounding for all the parts that have to be grounded.
• There are lots of connection wires between parts behind the LCD screen. When servicing or moving the set please take care not to touch or scratch them. Once they are damaged the screen would be unable to work and no way to get it repaired.
• If the connection wires, connections or components fixed by the thermo tropic glue need to disengage when service, please soak the thermotropic glue into the alcohol and then pull them out in case of damage.
• Special care must be taken in transporting or handling it. Exquisite shock vibration may lead to breakage of screen glass or damage to driving circuit. Therefore it must be packed in a strong case before the transportation or handling.
• For the storage make sure to put it in a place where the environment can be controlled so as to prevent the temperature and humidity from exceeding the limits as specified in the manual. For prolonged storage, it is necessary to house it in an anti-moisture bag and put them altogether in one place.
• Display of a fixed picture for a long time may result in appearance of picture residue on the screen, as commonly called “ghost shadow”. The extent of the residual picture varies with the maker of LCD screen. This phenomenon doesn’t represent failure. This “ghost shadow” may remain in the picture for a period of time (several minutes). But when operating it please avoid displaying still picture in high brightness for a long time.
• The front panel of LCD screen is of glass. When installing it please make sure to put it in place.
• For service or installation it’s necessary to use specified screw lest it should damage the screen.
• Be sure to take anti dust measures. Any foreign substance that happens to fall down between the screen and the glass will affect the receiving and viewing effect.
•  When dismantling or mounting the protective partition plate that is used for anti vibration and insulation please take care to keep it in intactness so as to avoid hidden trouble.
• Be sure to protect the cabinet from damage or scratch during service, dismantling or mounting.

LG PLASMA 42PJ350 _ 600Hz SUB-FIELD DRIVING

LG PLASMA 42PJ350 _ 600Hz SUB-FIELD DRIVING

SUB-FIELD DRIVING

600 Hz Sub Field Driving is achieved by using 10 sub-fields per frame process (vs. Comp. 8 sub-field/frame)

No smeared images during fast motion scenes

Sub Field firing occurs using wall charge and polarity differences between Y-SUS and Z-SUS signals.

TECHNICAL TERMS - USED AS ABBREVIATION IN TV & DISPLAY FIELD

TECHNICAL TERMS - USED AS ABBREVIATION IN TV & DISPLAY FIELD

TFT-LCD:  (Thin film Transistor Liquid Crystal Display)

ADC(Analog to Digital Converter):  This is a circuit that converts from analog signal to digital signals.

PLL(Phase Locked Loop):  During progressing ADC, Device makes clock synchronizing HSYNC with Video clock.

Inverter:  Device that supplies Power to LCD panel lamp. This device generates about 1,500~2,000V.

AC Adapter:  Device that converts AC(90V~240V) to DC(+12V or 14V)

SMPS(Switching Mode Power Supply):  Switching Mode Power supply. This design technology is used to step up/down the input power by switching on/off.

FRC(Frame Rate Controller):  Technology that changes the number of frames displayed on screen per second.  TFT-LCD panel requires 60 frames per second.  This technology is needed to convert input image to 60 frames per second regardless input frame quantity.

Image Scaler:  Technology that converts an input resolution to another resolution.(ex. 640* 480 to 1024*768).

Auto Configuration(Auto adjustment):  This is an algorithm to adjust monitor to optimum condition by pushing one key.

OSD(On Screen Display):  Customers can easily control the screen settings using the OSD.

FINE:  The "Fine" adjustment is used to adjust visibility by controlling phase difference.

COARSE:  This adjustment adjusts the display by tuning Video clock and PLL clock.

DVI (Digital Visual Interface):  This provides a high speed digital connection for visual data types that is display technology independent.  This interface is primarily forcused at providing a connection between a computer and its display device.

L.V.D.S.(Low Voltage Differential Signaling):  A kind of transmission method for Digital. It can be used from Main PBA to Panel.

T.M.D.S:  (Transition minimized Differential Signaling):  a kind of transmission method for Digital.  It can be used from Video card to Main PBA.

DDC(Display data channel):  It is a communication method between Host Computer and related equipment.  It enables Plug and Play between PC and Monitor.

EDID:  Extended Display Identification Data PC can recognize monitor information such as Product data, Product name,Display mode,Serial number and Signal source, etc Data is recognised via DDC Line linking PC and Monitor.

Dot Pitch:  The image on a monitor is composed of red, green and blue dots. The closer the dots, the higher the resolution. The distance between two dots of the same color is called the 'Dot Pitch'. Unit: mm.

Vertical Frequency:  The screen must be redrawn several times per second in order to create and display an image for the user. The frequency of this repetition per second is called Vertical Frequency or Refresh Rate. Unit: Hz.  Example: If the same light repeats itself 60 times per second, this is regarded as 60 Hz.

Horizontal Frequency :  The time to scan one line connecting the right edge to the left edge of the screen horizontally is called Horizontal Cycle. The inverse number of the Horizontal Cycle is called Horizontal Frequency.  Unit: kHz.

Interlace and Non-Interlace Methods:  Showing the horizontal lines of the screen from the top to the bottom in order is called the Non-Interlace method while showing odd lines and then even lines in turn is called the Interlace method. The Non-Interlace method is used for the majority of monitors to ensure a clear image. The Interlace method is the same as that used in TVs.

Plug & Play:  This is a function that provides the best quality screen for the user by allowing the computer and the monitor to exchange information automatically.  This monitor follows the international standard VESA DDC for the Plug & Play function.

Resolution:  The number of horizontal and vertical dots used to compose the screen image is called 'resolution'.  This number shows the accuracy of the display.  High resolution is good for performing multiple tasks as more image information can be shown on the screen.