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can a CRT function on it's side?

Discussion in 'Electronic Repair' started by robobass, Jan 28, 2004.

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  1. robobass

    robobass Guest

    I was in an MRI clinic and noticed that the monitors were set up tall
    and narrow. They weren't just turned on their sides, they were made
    this way. This was to better view spinal column images. I thought this
    would be great for me, a musician, as I could better view sheet music.
    I tried turning my 19" crt 90 deg, but it messed up the color and the
    focus. Are there certain crt designs that would function on their
    sides? I imagine LCDs would work this way, but I don't want to spend
    the money. Why did I have this problem? How it it that an electron
    beam would be affected by gravity?
    Robobass
     
  2. John Bachman

    John Bachman Guest


    When you turn a CRT on it's side the convergence is disturbed by the
    change in direction of the earth's magnetic field. You could do it
    with an LCD or plasma display but not a magnetic deflection device
    such as a CRT.

    John
     
  3. I think it should be OK if it's turned on while on it's side, so the deguass
    circuit does it's thing. I have seen large (25" and up) CRT's react poorly
    to being moved while ON.

    Mark Z.
     
  4. Tim Mitchell

    Tim Mitchell Guest

    If you degauss the CRT once it is on its side, normal operation should
    be restored.

    Getting the software to display correctly could be more of a problem.
     
  5. John Bachman

    John Bachman Guest

    I don't think that degaussing will do the trick. Degaussing removes
    residual magnetism within and around the CRT itself but has no effect
    on the earth's magnetic field.

    Guess I will do a little test later today just to make sure.

    John
     
  6. Back in the mid 1980s Apple and at least one other mfg made monitors that
    could be rotated for working on legal sized documents. I see no reason why
    can't use yours rotated 90 degrees. Look for a deguass butoon or try
    turning it on and off several times.
    73
    hank wd5jfr
     
  7. Jerry G.

    Jerry G. Guest

    Normally a CRT cannot be directly put in its side and work directly. If you
    can find someone who is knowledgeable to redo the convergence and purity
    set-up for this type of operation it will work for you. The mask in the CRT
    would have to be degaussed on its side before doing the re-alignment of the
    purity and convergence set-up.

    A number of years ago, Apple came out with a CRT monitor that can be
    rotated. The CRT had a very good u-metal shielding, and they used some
    sophisticated alignment circuits in their design to compensate the purity
    and convergence for this. I had a look at one of these a number of years
    ago. I found that when it was on its side, it was not very perfect, but it
    was better than the average when run this way. This was not done simply.

    Even if you had your monitor aligned to work on its side, you will have to
    have the software for this, or your computer will be on the difficult side
    to use.

    There are some LCD monitors that are designed to be able to be rotated on
    its side. A descent monitor with this feature that is very good is the
    Samsung SyncMaster 171N. This one can be rotated to work at any angle from
    180 deg (normal) to 90 deg (side). This monitor comes with the software to
    accommodate this.



    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    I was in an MRI clinic and noticed that the monitors were set up tall
    and narrow. They weren't just turned on their sides, they were made
    this way. This was to better view spinal column images. I thought this
    would be great for me, a musician, as I could better view sheet music.
    I tried turning my 19" crt 90 deg, but it messed up the color and the
    focus. Are there certain crt designs that would function on their
    sides? I imagine LCDs would work this way, but I don't want to spend
    the money. Why did I have this problem? How it it that an electron
    beam would be affected by gravity?
    Robobass
     
  8. John Bachman

    John Bachman Guest

    Those were monochrome monitors - the change in magnetic field would
    cause a positional shift but convergence was not a problem.

    In that time period I was designing monitors for a large computer
    company. We shipped a new color monitor design to our folks in
    Australia and were puzzled when they reported that the convergence was
    off.

    I could hardly believe it when we found that the convegence problem
    was caused by the difference in the Earth's magnetic field between
    Australia and the US.

    A happy discovery was that if you break the field into vertical and
    horizontal components the horizontal is nearly identical but the
    vertical is nearly identical in magnitude but opposite in direction.
    So our solution was to turn the monitors upside down when aligning
    them here - then they were fine right side up in Australia.

    Those were low-resolution monitors. I doubt that the upside down
    trick would be adequate for today's monitors. Monitor manufacturers
    today use a controlled magnetic field room in which they can create
    the magnetic field for any place on earth. They set it up, align the
    monitors and ship the units to the right place.

    John
     
  9. Jerry G.

    Jerry G. Guest

    This thing with the monitors going to Australia was very amusing! This was
    a very smart idea to align them upside-down!

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    =========================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    =========================================


    Those were monochrome monitors - the change in magnetic field would
    cause a positional shift but convergence was not a problem.

    In that time period I was designing monitors for a large computer
    company. We shipped a new color monitor design to our folks in
    Australia and were puzzled when they reported that the convergence was
    off.

    I could hardly believe it when we found that the convegence problem
    was caused by the difference in the Earth's magnetic field between
    Australia and the US.

    A happy discovery was that if you break the field into vertical and
    horizontal components the horizontal is nearly identical but the
    vertical is nearly identical in magnitude but opposite in direction.
    So our solution was to turn the monitors upside down when aligning
    them here - then they were fine right side up in Australia.

    Those were low-resolution monitors. I doubt that the upside down
    trick would be adequate for today's monitors. Monitor manufacturers
    today use a controlled magnetic field room in which they can create
    the magnetic field for any place on earth. They set it up, align the
    monitors and ship the units to the right place.

    John
     
  10. James Sweet

    James Sweet Guest

    Try it, it works fine, when I had a smaller monitor I used to turn it on
    it's side regularly to play vertical monitor games with MAME. Anyone
    remember those old Radius Pivot monitors? They were designed so you could
    rotate them 90 degrees and the software would detect that and flip the
    image. Also arcade monitors for horizontal and vertical orientation are the
    same monitor, just mounted differently. As long as you degauss it in it's
    new orientation it'll work perfectly.
     
  11. James Sweet

    James Sweet Guest


    IIRC the ATI Radeon drivers let you do this.


    As an experiment I just tried running my Sony 22" CRT on it's side, after
    degaussing the image looked fine (but sideways)
     
  12. Guest

    Guest Guest

    Others mentioned the electromagnetic issues relating to turning the
    CRT on its side. There is one other issue and that is convective
    thermal cooling of the remaining circuitry in the monitor. That is,
    the ol' "heat rises" principle and that's how the heat exits the monitor,
    through the top. It's likely that some circuits could run hotter because
    there may not be cooling vents on the side of the monitor enclosure.

    A cheap fan of any type would probably remedy the problem though.

    b.
     

  13. Monitors/tv sets are normally set up for the "average" magnetic field
    in the northern hemisphere unless they are known to be going to a
    location in the southern hemisphere. When a tv/monitor is operated on
    its side, the earth's magnetic field has the greatest effect on the
    purity, and somewhat lesser effect on the convergence. Degaussing
    will help the purity, but may not be 100% effective. If the purity
    must be manually readjusted, then the convergence usually must also be
    readjusted. LCDs are the way to go if you want to be able to switch
    back and forth without any extra problems.

    H. R. (Bob) Hofmann
     
  14. robobass

    robobass Guest

    Thanks for all the advice. The software would not be 100% necessary if
    I could quickly switch between verticle and sideways positions, but
    that seems not an option with a large color CRT. 19" monitors have
    become so cheap that I would entertain keeping two on my desk (one
    normal and one sideways) and getting a dual port graphic card. But,
    that would wreck the shen fui of my work area. I'm not sure I want to
    have an LCD monitor because I keep no TV in the house and I use my
    computer to watch DVDs. Well anyway, If I really get serious about
    this idea, at least I know my options.
    Robobass
     
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