A Certification, Hardware IS 148

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A Certification, HardwareIS 148

• Video
• Chapter 11

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A Serious Safety Issue

• Unless you are specifically trained in TV repair
  or other high voltage work, under no
  circumstances should you open up a monitor case.
• Repairing monitors is beyond the scope of
  CompTIAs A certification.
• Monitors have very high voltage inside that can
  kill YOU!
  

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CAUTION 25kV 25,000 volts!
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Inside the monitor
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Electron Gun
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Raster Lines

• Lines are drawn on the screen one line at a time
  moving left to right.
• Each sweep of across the screen is called a
  raster line.

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Horizontal Refresh Rate

• Raster lines continue to be drawn from top to
  bottom of the screen.
• Time to draw one line and be ready to start the
  next is called Horizontal Refresh Rate.
  

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Vertical Refresh Rate

• The amount of time required to fill the screen
  and return the electron gun to the upper left
  hand corner of the screen is called the Vertical
  Refresh Rate.

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Vertical Refresh Rate

• The number of times an entire display screen is
  refreshed, or redrawn, per second.
• Measured in Hertz
• display systems typically range from 56Hz to
  well over 100Hz.
• A minimum of 70Hz is recommended to help prevent
  eye strain.
• Too high of a rate will cause distortion in the
  display.
• Too low of a rate will cause headaches in users.
  
  

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Changing The Refresh Rate Frequency
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Phosphor

• A substance that emits light when excited by
  radiation.
• The electron gun provides the radiation for
  phosphor contained on the back side of the
  Cathode Ray Tube. CRT
• Special types of phosphor emit different colors
  when exposed to a beam of electrons.
  

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Phosphor Dots
Red, Green, and Blue phosphors
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Color Monitors

• The color CRT has three electron guns
• Red phosphors
• Blue phosphors
• Green phosphors
  

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Shadow Mask

• Directly behind the phosphor is a shadow mask
  that prevents an electron beam from lighting the
  neighboring color dot.
• In a color monitor there are actually three
  different color guns.
  

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Shadow mask
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PIXELS

• PIXEL is an acronym for Picture Elements.
• It is the area of phosphors that is lit at one
  time when it is struck by the electron beam.
• It is the smallest area on the CRT screen that
  can be lighted.
• A pixel must be made up of at least one each red,
  green and blue phosphor.
• The smallest pixel then would contain one
  phosphor of each color.
  

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Monitor Resolution

• Resolution
• Number of Horizontal pixels times
• Number of Vertical Pixels
• Horizontal x Vertical
• Resolutions all match a 43 Ratio
• The 43 ratio is called the Aspect Ratio
• Example 800x600 (200)
• Example 1024x768 (256)

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Color Triad
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Pixels vs Resolution
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VGA By Definition

• 16 Colors
• 640 x 480 pixels resolution

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Dot Pitch

• Dot Pitch is the diagonal between phosphor dots
  of the same color.
• Dot Pitch is expressed in millimeters.
• Monitors with lower the dot pitch numbers usually
  have sharper images.
• For a CRT today a dot pitch of .28 is typical.
  

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Dot Pitch Measurement
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Bandwidth

• Defines the maximum number of times the electron
  gun can be turned on and off per second.
• Relates how quickly an monitor can put a picture
  on the screen.
• Typical value would be 150 MHz.

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Bandwidth

• Bandwidth defines the maximum number of times an
  electron gun can be turned on or off per second
• Bandwidth is measured in megahertz (MHz)
• How fast the monitor can put an image on the
  screen
• VRR Vertical Refresh Rate

Maximum VRR bandwidth ? pixels per page
For example, a 17-inch monitor with a 100MHz
bandwidth and a resolution of 1024x768 can
support a maximum VRR of 127 Hz 100,000,000 ?
(1024x768) 127 Hz
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Bandwidth number of times the electron gun can
be turned on and off per second.
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LCDs

• Liquid Crystal Displays
• Thinner and lighter
• Much less power
• Flicker free
• Dont emit radiation
• Called Flat Panels or Flat Panel Displays

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Light

• Travels in waves
• Wavelength determines the color
• If light came at us in one wavelength we would
  see just one color
• We usually see many different wavelengths which
  looks white

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How LCDs Work

• Liquid crystals take advantage of the property of
  polarization
• These crystals are composed of specially
  formulated liquid, full of long, thin crystals
  that always orient themselves in the same
  direction
• The crystals act exactly like a liquid polarized
  filter

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LCD Panel Technologies

• There are two technologies being used to
  manufacture LCD panels.
• Passive Matrix
• Active Matrix ( thin film transistor)

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Passive Matrix

• Use three matrices to produce color
• Above the intersections the glass is covered with
  tiny red, green, and blue dots.
• The amount of voltage will allow different levels
  of red, green, and blue

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Dual-Scan Passive Matrix

• Passive matrix is slow and tends to create an
  overlap between pixels
• Dual-scan passive matrix is faster by refreshing
  two lines at a time
• Still used on some lower-end LCD panels

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Thin Film Transistor (TFT)

• Thin Film Transistor (TFT) is also known as the
  active matrix
• It uses one or more tiny transistors to control
  each color dot
• TFTs are brighter, with better contrast, can
  handle a variety of colors, and have a much wider
  viewing area

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LCD Resolution

• All LCD monitors have a native resolution such as
  1024x768
• You can not run a LCD at a resolution higher than
  the native one.
• Running at a resolution lower than the native
  resolution will degrade the image quality.
• Always set a LCD at native resolution.

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Interlacing Monitors

• An interlacing monitor sweeps alternate lines on
  the CRT.
• First the odd number lines
• Second the even number lines
• It takes two complete sweeps to complete the
  image.
• Used by lower cost monitors to give the sense of
  faster refresh rates
• Will cause user headaches.

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Interlace or not?
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Windows Help
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RAMDAC Chip

• Random Access Memory Digital-to-Analog
  Converter.
• Included on all VGA and better cards to convert
  digital information into analog information for
  the analog CRT monitors.
• LCD require a digital signal.
• To use a LCD monitor on a regular video card it
  will require an analog to digital converter.
• Many LCD monitors make the conversion and are
  called analog LCD monitors.
• Most LCD monitors will work as a digital or
  analog monitor.

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Digital Video Interface standard

• The Digital Display Working Group (DDWG) created
  the specification for the DVI connector to
  accommodate both analog and digital interfaces
  with a single connector, though there are
  actually three different configurations

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DVI Connectors

• DVI-A is designed for analog-only connections.
• DVI-D handles only digital signals
• DVI-I (for integrated) is a single connector that
  can handle either analog or digital signals.
• Many graphics cards now come with digital
  connections. Most of these use DVI-D, but a
  simple adapter will let them connect to a DVI-I
  cable.

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LCD Connections

• We now see LCD monitors that use digital video
  cards (no RAMDAC) and a totally different Digital
  Video Interface (DVI) connector
• DVI-A (analog)
• DVI-D (digital)
• DVI-A/D or DVI-I (interchangeable) accepts either
  

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The Video Card Page 363

• The video card handles the video chores within
  the PC.
• The video card processes information from the CPU
  and sends it to the monitor.
• Two major parts of the video card
• Video RAM
• Video Processor
  

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Video RAM

• Stores the video image
• Todays video cards may use RAM especially
  designed for video applications or RAM like that
  used on a Motherboard.
• SGRAM Synchronous Graphics Random Access
  Memory
• GDDR Graphics Double Data Rate
• DDR SDRAM
• DDR2 SDRAM
  

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Text Video and Video RAM

• Initially the text video cards would display only
  the 256 ASCII characters and no color was
  available.
• It was possible to make a character bright, dim,
  normal, underlined or blink.
• For a screen with 80 characters per row and a
  vertical height of 24 rows, you would need only
  1,920 bytes of RAM. (80 characters x 24 rows x 8
  bits per character)

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The Graphics Video Card

• The next development after the text video card
  was the graphics video card.
• Graphics video cards could turn any individual
  pixel on the monitor screen on or off.
• The video graphics card required much more RAM.
• A resolution of 320 x 200 pixels would require
  64,000 bits or 8,000 bytes of RAM. ( 1 bit per
  pixel on or off )

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Color Graphics Cards

• Multiple bits are required to define the color
  increasing the need for RAM.
• To display 256 colors it takes 8 bits.
• For true color (16.7 million colors) you would
  need 24 bits per pixel.
• Color depth is usually represented in terms of
  how many bits are used to represent the color
  rather than the number of colors to be
  represented.
• A color depth of 24 bits, not a color depth of
  16.7 million colors.
  
  

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Video Cards and Standards

• VGA - Video graphics array
• 16 colors at a resolution of 640 X 480 pixels
• XGA - Extended graphics array
• 16-bit color at a resolution of 1024 X 768
• SVGA - Super VGA
• Extensible standard - meaning that VESA adds to
  the list as higher resolutions and deeper color
  depths develop.
• VESA Video Electronics Standards Association.
  

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Need For A Faster Video Bus

• The PCI expansion slot is limited to 32-bit
  transfers at 33 MHz or bandwidth of 132 Mbps.
• It is difficult for the PCI bus to handle some of
  the video demands especially if the CPU is busy
  multi-tasking.
• PCI has a maximum bandwidth of 132 MBps.
• High color demands require much more bandwidth.
  
  

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Accelerated Graphics Port

• Intels answer to a desire for increased video
  bandwidth.
• AGP is a single special port that is dedicated to
  video.
• Derived from the 66 MHz, 32-bit PCI 2.1
  specification
• Uses its own personal data bus and supports
  pipelining

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AGP Connection
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AGP Advantages over the Graphics Port

• AGP resides alone on its own data bus connected
  directly to the Northbridge.
• AGP uses pipelining commands
• AGP employees sidebanding which allows the card
  to send and receive commands at the same time.
• AGP x 8 will allow for more that one AGP device.
  

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Graphics Processor

• The most important decision in buying a video
  card is the graphics processor.
• Most video processors are made by
• NVIDIA
• ATI
• Matrox
• Third-party video card manufacturers use one of
  these video processors on their cards

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Video Memory

• The video RAM constantly updates to reflect every
  change that takes place on the screen.
• Low cost video cards (50-100) use standard DRAM
  for video data storage.
• DRAM slows the graphics card because it needs to
  be refreshed 18.5 times per second. These
  bottlenecks are overcome by
• Increasing the width of the bus between video RAM
  and the video processor
• Using specialized RAM

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Video Memory

• The two older styles of RAM specifically designed
  for video are
• Video RAM (VRAM)
• Dual-port memory that can send and receive at the
  same time.
• DRAM can only send or receive at a given time
• Windows RAM (WRAM)
• Dual-port memory that is slightly faster than
  VRAM

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More Video RAM

• Synchronous graphics RAM (SGRAM)
• Synchronized to the system clock
• Extremely fast
• Newer, generalized RAM types such as DDR SDRAM
  are often used instead of the specialized video
  memory.
• Most now use GDDR

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Physical Installation Issues

• High end video cards are tall and may not fit in
  all cases
• High end video cards run very hot
• Leave the slot next to an AGP card empty to allow
  better air flow

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Installing and Configuring Video Software
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Video Drivers

• Like any other piece of hardware the Video Card
  needs a driver to function.
• Always use the most recent driver version for
  your video or graphics card.
• A good place to start in the adjustment of a new
  video card is 32-bit color.

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Finding Your Monitor Refresh Rate
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Windows XP Display Properties
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Drop down menu for selection
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Display Properties Settings Tab

• Alternate Click on the Desk Top
• Select Properties
• Choose Settings Tab
• Click on the Advanced Button

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Monitor and Video Card Properties

• Select the Monitor Tab

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Drop down menu for selection
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Drivers

• When changing or installing a new video card
  Windows should recognize the new hardware and
  install drivers.
• Drivers for the new card can be updated using the
  update driver button on the property page.
  

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Removing Old Drivers

• Drivers for older video cards should be removed
  after you determine that the new card will
  function properly.
• If no drivers are found for a card the machine
  will boot to safe mode and VGA.

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DirectX

• Allows programmers to talk directly to a piece of
  hardware.
• DirectX provides the speed necessary for advanced
  games.
• DirectX is not just for video, also supported
  are
• Sound
• Networking
• I/O devices
  

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DirectX

• DirectX provides direct access to hardware as
  follows
• DirectDraw for 2-D graphics
• Direct3D for 3-D graphics
• DirectInput for joysticks and game controllers
• DirectSound for waveforms
• DirectMusic for MIDI devices
• DirectPlay for multiplayer games
• DirectShow for video and presentation devices

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DirectX Diagnostic Tool

• Accessories ? System Tools ? System Information ?
  Tools menu ? DirectX Diagnostic Tool

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DirectX Diagnostic Tool
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Run the Video Tests
Shows Tests and Results
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Cleaning Monitors

• Antistatic monitor wipes or antistatic cloths
  should be used for cleaning the monitor
• Do not use window cleaners
• Avoid commercial cleaning solutions on LCD
  screens
  

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Common Monitor Problems

• Control buttons are replaceable
• Check with the manufacturer
• Ghosting, streaking, fuzzy vertical edges
• Check the cable connections and cable itself
• Missing color
• Check cable for breaks, bent pins, and monitor
  adjustments

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Monitor Problems Continued

• Loss of brightness
• Normal with age, so use power management
• Internal adjustments may be made
• Cracked LCD monitors
• Not repairable
• All other LCD problems are repairable
  

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Common CRT Monitor Problems

• Improper focus
• Adjustments are inside close to the flyback
  transformer
• Hissing or sparking sounds and the smell of ozone
  
• Insulation rupture requiring a qualified
  technician
• Big color blotches
• Degauss
• Bird-like chirping sounds
• Monitor power supply
• Loss of brightness but the control is all the way
  up
• Time for a new monitor
• Single horizontal or vertical line or single
  white dot
• Repair shop
  

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Dos and Donts

• Do keep the screen clean
• Do keep the cables tightened
• Do use quality cabling
• Do use power management
• Do dispose of monitors properly by checking with
  your local waste disposal company

• Dont block the ventilation slots
• Dont use a refresh rate higher than recommended
• Dont leave the monitor on all the time even
  with a screen saver
• Dont place magnetic objects like unshielded
  speakers close to the monitor

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