Conference hydra::amiga_v1

     You will get a better answer in the  VIDEO conference, but I think
     the speakers near the screen are the culprits. The magnets in the
     speakers affect the colors etc. (really technical explanation eh?)
     Moving the speakers is not enough once the screen is affected. 
     I think what you need to do is called "degaussing".
     Dave (reaching beyond the realm of his expertise)

    I suppose that it's possible that someone passed a magnetic field
    close to the front of your CRT and wrecked the purity.  Typically, the 
    effect of damaged purity is large splotches of color or wrong color
    appearing in the image.  Something as simple as switching off a
    vacuum cleaner close to the face of the tube can do this.  You may have 
    to degauss the tube with a proper degaussing coil.  I've used other 
    sources, but the intense field generated by the coil is most effective.  
    One small warning, move your diskettes far out of the way if you try this. 

    Too bad Klipshman,
    
    	If the Kg4's are the culprits, I understand why. They have massive
    magnets in them. If you get them a few feet away from the screen, it
    may restore itself at least somewhat over time, but never totally. Dave
    (.1) was right, you have to degauss it....
    
    					bob
    
    

    Bob,
    
    It was my Fishers, the Klipsch are on the floor (where they belong).
    on the other side of the room...
    
    I've had the speakers up there for months at a time... no problems.
    There is however, a cable box on top of the speakers, (my room is a
    technological wonderland), so I wonder if this had anything to do with
    it.  Thing is, the cable box is at least 2 feet away from the
    monitor...
    
    Also, I've had an Air Conditioner running in the room.  It's on the
    same circuit as everything else in there, including the computer. 
    Could this have done it?
    
    Later...
    Steve
    
    

I was having a nearly identical problem with my 1080 - the color was off in
the lower corners of the display. The tech's looking at it tell me that:

1) The CBM 108x monitors have degaussing hardware in them, so the tube shouldn't
need degaussing.

2) One of the plates in the box to make the FCC happy has picked up a
magnetic field. This is probably the problem.

3) We'll purchase a degausser and do fix it for you.

4) The other problem....

I haven't seen the results yet; they're still working on that other problem.
2.0 is _ugly_ on a monochrome monitor.

	<mike

    You can usually carry your monitor to a TV repair shop and have them
    degauss it for you.  As .-1 said, most monitors (and TV's) made today
    have automatic degaussing circuitry in them which is activated when the
    monitor's power is applied.  Not to mention the obvious, but have you
    turned the power off and back on  (leave it off for at least 30 to 60
    seconds.) ???
    
    

    If the purity has been seriously scrambled, it usually takes a VERY
    strong fluctuating (alternating) magnetic field to undo the 'damage'.
    I've only seen a couple of monitors that had a degaussing circuit
    powerful enough to erase the residual magnetism causing the purity
    problem in one power-up cycle.  Enough power-up/down cyclings could 
    eventually undo the effect, but an official degaussing coil is the 
    preferred way to go.  There is a specific technique in the use of a 
    degaussing coil to insure a clean sweep.  This is experience speaking, 
    since I used to see a lot of  T.V. sets with this problem in the Old Days 
    (you remember them! :')) when I used to work in the 'real' world of 
    consumer electronics.             
    
    Modern T.V.'s had the circuitry built-in for a number of years.  I
    guess that a lot of housewives used to park and power-off their vacuum 
    cleaners in front of their sets ;'). 

Re: .*

I suspect the speakers.  Move them away, and see if the problem disappears.

A couple of years ago, I had a problem where the color in the upper left
corner of my 1080 monitor was bad.  Instead of Workbench blue, there was
a slight, but noticeable orange cast to the color.  Slowly, the orange
intensified and spread to a larger area.

The culprit: the Radio Shack minimus speakers I had mounted on the wall
behind the monitor (about a foot away).  The orange area was increasing
not due to any increasing damage to the monitor, but because I was moving
the monitor around a fraction of an inch over time.  That small change
in distance brought the monitor closer to the left speaker and made the
problem worse.

When I moved the monitor further away from the speakers, the problem
completely went away.  There was no permanent damage to the monitor
at all.

    That's good randy, but if the mask is magnetizable, the field can be
    static.
    The mask is the metal fine mesh that acts as a stencil for the beam f
    so that the beam hits the right color phosphors.
    Tom

    
    Well, the problem is fixed... I guess it was the speakers.  
    
    They are still above the monitor, but I turned them upside down so that
    the big woofer magnet is far away from the monitor.  Everything cleared
    up.
    
    It's funny though because I've had the speakers there before and had no
    problems...
    
    Thanks all...
    Steve
    

I've had (and still have) a similiar problem with my monitor.
I'm pretty sure the screen discoloration (corners especially,
but all greys are rendered somewhat green) began the day
I put a pair of tiny speakers on top of the monitor.
The whole effect may even have been compounded by my big
Cerwin-Vega speakers which were 12-18 inches away from system
for the duration of several years.

So, maybe degaussing will fix the monitor.  It never bothered
me so much, since you usually only notice the colors are bad
if you compare it to a "correct" monitor.

Now I have a question.  I have a "Tape Head Demagnetizer Thingy".
Is this Thingy working on the same principal as deguassers?
Could I use it on my monitor to correct the problem?
It's a strange plastic looking rod which hums in your hand
as you place it and slowly remove it from tape heads.  Courtesy
of Radio Shack.

Betcha can tell I don't know much about it :-)

Dave

    Speaking of monitors... Could having an external floppy drive too close to
    the monitor cause read/write (mostly write) errors? Here's the situation.
    I've got an A500/C=2002 with my external AIRDrive sitting to the right
    of the monitor. This is a brand new drive. My original AIRDrive, purchased
    in Nov 89 started exhibiting write errors as well on brand new Sonys so
    I returned it to Omnitek under warranty. AIR confirmed that there was
    something wrong with the drive & replaced it with a brand new one. The
    original "gronked" like crazy; the replacement's extremely quiet. Now
    the replacement (< 1 month old) is starting in with write errors as well.

    I've been testing using DiskSpeed. Format a virgin floppy, run DiskSpeed,
    df1: gets write errors within a few minutes. Run DiskSpeed on the same
    floppy in df0: - runs to completion. I've gone back to a stock out of the
    box Commodore workbench just to eliminate anything s/w related that
    might be in my startup-sequence. Ran DiskSpeed overnight, with the vanilla
    WB1.3, with the drive moved away from the monitor. Ran to completion.
    Tried it again early this morning using the same floppy and it failed
    with write errors. 

    The difference: I turned the monitor off last night for the overnight run 
    since the vanilla WB doesn't have a screen blanker. Could the monitor be 
    causing the problem? This is driving me nuts. 

							-Dom

Please pardon all the typos in .-1.

    Yes, the demagnetizing rod works on the same principle. When something
    becomes "gaussed", it has a net magnetic field pointing in a given
    direction. To degauss something you put a strong magnetic field around
    the object. Then you rapidly switch the polarity of the field back and
    forth. Most Tape Demagnetizers employ a scheme where the field also
    becomes gradually weaker, in your case, pulling the rod away makes it
    weaken. A good degaussing coil is quite different from any tape
    demagnetizer however, and I could almost guarantee that the Radio Shack
    rod wouldn't fix your monitor. (Although you may want to see what
    happens if you use the rod around the edges of the screen....Might
    help, might hurt, I don't know)
    
    					bob
    
    

    Someday read one of those warning labels that comes with floppies (or
    the ones printed on the back of 5 1/4" disk sleeves). It undoubtedly
    says to keep disks away from stray magnetic fields. You're monitor
    probably utilizes some of the strongest magnetic fields in your room.
    Generally fields aren't too strong at the sides or the back - they are
    usually worst out the front, right at the screen being the worst of
    all. You can easily destroy the data on a disk by holding it too close
    to your screen. (I personally have corrupted a number of disks in this
    manner) If there are any stray fields making their way into your drive,
    it doesn't suprise me that it would screw up. Disks are pretty amazing,
    it surprises me that they work at all now that I know how they work,
    they are quite susceptible to outside forces. Even if your drive
    experiences no problems, or you are one of those people who puts disks
    on top of their monitor, a general rule is keep disks about a foot away
    from monitors. This means disk drives too, although since they are
    shielded, they can probably be a bit closer. I wouldn't put anything
    closer than 6" away, just for safety's sake.
    
    P.S. I wouldn't advise getting anymore AIRDrives, they don't sound too
    well shielded if that is infact your problem.
    
    					bob
    

    re: -.1
    I'm surprised.  I would expect the strongest magnetic fields to be near
    the flyback transformer of the monitor.  This is often on the side and
    back.
    Once I had a small black and white TV with a rotated image.  I had
    accidentally magnetized the case, so I demagnetized it with a hand-held
    adio tape eraser.  Too bad Radio Shack no longer has degaussing coils,
    which are big and round to show a similar field to the entire screen
    at once rather than a small localized field that only works on part of
    the screen at a time.  (OK, I'm guessing; sue me.).
    (no, don't).
    ;-)
    Actually, the earth's magnetic field can also magnetize a color tube.
    I also suggest going to a tv repair shop.  Actually, I think my tube is
    a little magnetized.  Maybe I will look into it.
    Tom

    The field from a monitor is almost all from the deflection coils and
    flyback transformer (which are both toward the back), but the sides and
    back are usually shielded whereas the front is not.
    
    Re: the small tape eraser.  As .-1 said, they have a very small field
    and will probably leave your monitor in worse shape than it found it. 
    The Degausser you need must present a uniform field to the entire
    display area and gradually get weaker (either internally or by pulling
    it away slowly) uniformly.
    
    Take a 40 pound magnet and rotate it sixty times per second while
    pulling it away from your monitor.  :^)