MONITOR FAQS
This section is presented as an aid to users that have an interest and
curiosity about the functions and terms used in the monitor industry.
The replacement cost of consumer monitors has successfully been lowered
to the extent that most manufacturers , the service industry and the replacement parts industry
are no longer supporting the repairs of these consumer products in the U.S.A.
Our monitor repair service is now specializing in the commercial market.
Our experience has shown that the high demands on a monitor screen
will greatly shorten the life expectation of a new monitor,and in many cases
monitors brought in for service after two years are beyond economical repair
because of a worn out display tube (CRT).
It has become necessary however, to service and maintain the larger
and the specialized screens strictly for economic reasons. The display
tubes have a much higher manufacturing cost and ready replacement is not
an economical possibility.
PRIORITY SERVICE
Whenever necessary our policy has been to provide priority monitor
service . When units are available, we may supply loaner monitors as part of our monitor
service program to qualified commercial customers. We occasionally require
additional time in order to procure proper replacement parts. In this case we do
everything possible to minimize your downtime including the use of one of
our "loaner monitors".
THE DISCOUNT MARKET
With millions of of display cells in the large screen monitors the
manufacturing reject rate is a problem, thus driving up prices for premium tubes.
Non-premium tubes also known as "Consumer grade" are used in the discount market.
The last two years has brought some exciting changes and recently the introduction
of the 19 and 21 inch size flat screen tube, with dramatic price reductions.
LARGER SCREENS
In addition to more pixels the larger and specialized screens require
more precise electronics and deflection yokes to guide the light beam accurately
as it sweeps across the screen. Larger monitors need higher horizontal
sweep rates to produce smooth scanning of the available display area.
MONITOR RATING
All monitors are rated by what is commonly called "resolution." which
is a relative description of the usable workspace on your screen. This
is always measured in a unit called a pixel (short for picture element).
Dot pitch measurement by itself can be misleading and is only one of the
useful indicators of monitor display tube performance.
PIXEL
A pixel is a single white dot surrounded by a black background, of
the smallest size that the monitor could properly focus. This requires
a number of individual color cells, in most cases around five individual
color cells make up a period (.).
Dot Pitch
The term "dit pitch" is the measurement in milimeters of the distance between
two adjacent phosphor color elements. There are two systems in use today and the term
is sometimes improperly used. The triad dot shadow mask measurement is accurate as
described above.
The Aprature grille such as used in the trinitron tube from SONY, is composed of a slotted
steel membrane tightly stretched between a heavy spring steel frame. This assembly
resembles a piano string assembly and the individual "strings" will vibrate unless a
damping wire is strung tightly across the membrane. This is the source for the two
faint lines visible on the trinitron tube.
This "mask" directs the red gun to the red phosphor strip. The distance (in MM.) of two
adjacent phosphor strips of the same color is the "pitch" measurement.
It is near impossible to compare the two crt measurements.
RESOLUTION
If the horizontal scan line is 11 inches long, then multiply the pixel-per-inch
(85) by 11 inches and you have 850 maximum pixel density. To achieve this
resolution you need a premium C.R.T., with a .22 pitch , along with a superbly
functioning chassis.
IBMTM HISTORY
The IBMTMCompany produced a high resolution 16 inch monitor referred
to as the 8514. This monitor was rated at 1024 X 768 with the horizontal
sweep rate at 35.5 khz. and the vertical at 87 hz interlaced, using a slow
phosphor display screen. This was excellent for text and slow moving images
and did not have an objectionable flicker that was evident in competitive
monitors using fast phosphor tubes. This is the origin of the "interlaced"
fallacy. Due to lack of information many thought that to escape the annoying
flicker one simply had to purchase a new "non-interlaced" monitor. As a
matter of fact, all older 640 X 480 monitors run at 60 hz. non-interlaced vertical
refresh. The newer Vesa standard monitor run at higher refresh and a 37 khz.
horizontal sweep frequency.
Non-Interlaced
The so called "non-interlaced" monitors produce a better, smoother picture
by simply increasing the number of horizontal scan lines to 48,000 hz.or higher.
This equates to about 3 + times as many lines as on a television set. We
presently service monitors with up to 1600 horizontal lines. This
high quality monitor requires a special video interface that will supply
a horizontal sweep rate close to 100khz.
INTERLACED
The INTERLACED operational mode was an adaptation from the narrow bandwidth
television industry. The home television signal has a 30 hz vertical sync.
In order to get the picture as you see it today, the video signal was split
up and half of the picture was displayed on each interlaced frame producing
twice the number of vertical lines displayed. The problem is in accurate
control of the timing signals to produce accurate physical placement of the
raster lines producing an annoying movement on the screen.. When you have
florescent room lighting, the stroboscopic effect is seen and the monitor
image will appear to flicker.
This technology is only acceptable for monitors with the slow acting phosphors
and low resolution. The 87 hz vertical refresh is normally an INTERLACED mode.
HORIZONTAL SCAN
As the height of the picture increases, it is necessary to increase
the number of horizontal lines to create a smooth line-free display image.
To do this, the monitor and the interface card increase the frequency of
the repetitive horizontal scan rate. The higher the horizontal scan rate,
the more likely the monitor will be capable of a great picture. As the
horizontal scan rate increases, it is necessary for the bandwidth to be
increased also. Eventually the designer stumbles into the price barrier.
Video Bandwidth
In order to consistently reproduce the video information
at a high resolution, the monitor must have a wide video bandwidth. In the electronics
industry, engineers use a term called "DECIBELL" (abbreviated DB.) to quantify
the video signal input level to the luminence or light level of the display (output).
In order for the term to be meaningful for comparison purposes, the bandwidth expressed
in mhz. must be within +- 3DB . Simply stated, for a fixed given input voltage(.07v pp),
the light output on the display must remain within a relatively consistant level of +- 3db
for signals from 0 to quoted bandwidth in MHZ.
For 1024x768, 125 mhz +-3db is unacceptable. A rating of 200 mhz bandwidth without the
+-3db qualifier is meaningless.
The video bandwidth must be in the 100 mhz. or above range to produce sharp
and crisp images especially with the newer .22 pitch tubes.
VIDEO INTERFACE
The computer requires a "video Interface" sometimes referred to as a video card
to communicate with your monitor.
Your operating system will pass on the selected mode information enabling the on board
microcontroller to accepts the video information from the system then it modifies,
and stores the video stream and passes the information on to the monitor.
Large amounts of "fast" memory will provide you with more colors
and faster display performance. Avoid the "discount video cards" because we have found all
kinds of problems and inconsistencies with these products. Remember "the video interface
is the master and the monitor is the slave".
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PERFORMANCE PARAMETERS
Your monitor is the single most important component of your computer system
and You will never regret purchasing the "top of the line" product for your needs.
Most customers in the past were concerned about "Dot Pitch" but have now become more
concerned about the visual quality. The flat screens, high resolution, high refresh rates,
and recently the USB and solid state screens top the list of desirable features.
Warranties extend up to 5 years on quality monitors. Our service department has
encountered a large number of "bargain" monitors brought in for repairs shortly
after the 1 year warranty has expired, and we find it near impossible to obtain
any parts rendering the "bargain purchase" worthless in one year! A very expensive
lesson learned, and usually the unhappy person is happy to buy the real economy
monitor even though at a higher initial purchase price! REMEMBER: Marketing companies
have only one goal: Supply a product to make a PROFIT!!
All analog monitors can produce thousands of colors,
it is inherent in the design. The limitation on color registration is directly
related to the available video memory on the interface card and the mode
selected. The original VGA is an analog device and 256 colors at 320 X
200 resolution was advertised.
This same system could also produce the higher resolution of 640 X
350 and 640 X 480. However, the number of possible colors was reduced to
16 because the original IBMTM pc was supplied with a built-in video interface
with only 256 kb of memory. At that time most users were familiar with
digital monitors that were limited to a maximum of 64 colors and were not
adequately informed about the infinite number of colors possible with the
analog monitors (television sets are analog.)
Enterprising manufacturers produced a better video interface for the
clone market and supplied 512 kb. of video memory and advertised their
product as a Super VGA. Now the user could have 256 colors at 640 X 480
resolution. Many, many people bought the advertising and replaced their
perfectly usable monitors for the new SUPER VGA monitors when it was actually
the video interface that was upgraded.
GUIDELINES
The following guidelines are safe to follow with the current monitors
(2000)
14 inch monitor is adequate for 800 x 600 resolution.
15 inch monitor is adequate for 1024 x 768 resolution.
17 inch monitor is adequate for 1024 x 768 resolution.
19 inch monitor is adequate for 1280 x 1024 resolution.
21 inch monitor is adequate for 1600 x 1280 resolution.
MISMATCH
If you use a higher resolution exceeding these guidelines, Your monitor
may deliver adequate pictures but you can also run into a "MISMATCH."
The following technical description may help you understand how the picture
will be compromised: The density of the pixels addressed by the higher
resolution video signal from the video interface will be greater than the
physical pixel density of the CRT. This creates a "MISMATCH" in that the
video signal modulates the electron beam which will be directed at a number of
non-existent cell and therefore lost.
This is the reason for the "dancing" and flickering of small icons when the higher
resolution modes are utilized on the smaller monitors.
VISUAL QUALITY
Your software may allow you to keep several icons on your screen or
open several windows at the same time, but your ability to focus - the
visual quality, depends on the quality of your monitor. The newer monitors
of reasonable quality are using INVAR TMshadow masks and dual focus construction
with expanded video bandwidth along with computerized dual focus in order to reproduce complex
video streams.
MONITOR DRIVERS
Monitor drivers: We have
been inundated with hundreds of requests for driver programs for a wide
variety of monitors in our "ASK ERV" forum board.
In reality
the newer monitors are automatically configured by the utilization of the
communication pins number 9, 12, and 15 which were unused on older monitors,
Pin 9 on the newer monitors uses +5v from the video card to supply power
to an eeprom on the monitor video board. This eeprom supplies setup information
to the Windows setup program through the video cable data line # 12
with all signal transfer synchronized through the clock line on pin # 15.
If one or more of these pins are missing, your monitor is NOT plug &
play!. Your video interface card must also implement the plug & play
protocall as well.
These are just "bells and whistles" since you can manually setup Windows
2000 TMfor your monitor.
This confusion comes from the expectation that all of the monitor manufacturers
would embrace the "plug and play" concepts from Microsoft Corp. in their
production of Windows 95 TMoperating system. While it is true that some manufacturers
are listed within Windows TMsetup programs, and the listed monitors work
well, It is also true that you can have great success if you use the WindowsTM "standard Monitor" setup selection then select the "highest resolution"
supported by your monitor. I have found that the Microsoft TMdrivers to do
an excellent job.
Common settings: The following
sweep frequencies will be generally helpful to the users that set up the
software for the monitors. and we will only list the common SVGA modes. You can use these
listing for your Linux TM system XFree86 TM monitor configuration.
Setting frequencies incorrectly can lead to damage to your monitor. The X Window system
only addresses video modes which drives the monitor in the given frequency range.
Entering frequencies that the monitor was NOT designed to support can severly damage
your monitor.
- SVGA MODE VGA60 horizontal 31.469 khz vertical 59.941 hz.
640x480
- SVGA MODE VGA103 horizontal 46.874 khz vertical 75.000 hz
800x600
- SVGA MODE VESA85 horizontal 53.674 khz vertical 85.061 hz
800x600
- SVGA MODE VESA75 horizontal 60.023 khz vertical 75.029 hz
1024x768
- SVGA MODE VESA85 horizontal 68.667 khz vertical 84.997 hz
1024x768
- SVGA MODE VESA horizontal 63.981 khz vertical 60.020 hz 1280x1024
- SVGA MODE VESA85 P horizontal 91.146 khz vertical 85.024
hz 1280x1024
- SVGA MODE VESA75 horizontal 79.976 khz vertical 75.025 hz
1280x1024
- SVGA MODE VESA70 horizontal 87.500 khz vertical 70.000 hz
1600x1200
- SVGA MODE VESA75 horizontal 93.750 khz vertical 75.000 hz
1600x1200
The above listing represents the latest published info taken from
a new monitor's users manual preset . Your settings may vary slightly depending
on horizontal phase (position) settings.
VGA MONITOR PINOUTS
The Vga cord pinouts are as follows:
- Pin # 1 Red Analog signal 0.7 volt P-P
- Pin # 2 Green Analog signal 0.7 volt P-P
- Pin # 3 Blue Analog signal 0.7 volt P-P
- Pin # 4 ID connected to 10& 11 for color.
- Pin # 5 Ground
- Pin # 6 "
- Pin # 7 "
- Pin # 8 "
- Pin # 9 Newer monitors uses +5v from the video card to supply power to
an eeprom on the monitor video board. This eeprom supplies setup information
to the operating setup program through the video cable .
- Pin # 10 Id connect to pin # 4 and pin # 11
- Pin # 11 Id Connect to pin # 4 and pin # 10
- Pin # 12 Plug & play data line.
- Pin # 13 Horizontal Sync. Digital levels + or - dependant on mode.
- Pin # 14 Vertical Sync. Digital levels + or - dependant on mode.
- Pin # 15 Plug & play clock line
Special Note: Before you
purchase your monitor, carefully read the warranty and instructions for
servicing and repair. We strongly recommend that you check on the availability
of service parts, and consider only the product of an established manufacturer.
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