rotate monitor and red disappears

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Archived from groups: alt.games.mame (More info?)

I tried running with a rotated computer monitor last night and to my suprise
the red color disappeared. At first I thought it was a software problem,
but then I picked up the monitor and rocked it side to side. When it was in
normal landscape mode the colors were fine. When it was on its side the
color mix was decidedly purple and green.

Is this expected? If so, are there certain monitors that do not behave this
way?

Thanks,
John
--
"Nature and nature's laws lay hid by night
God said, "Let Newton be," and all was light. -- Alexander Pope
 
Archived from groups: alt.games.mame (More info?)

John Leveille thought about it a bit, then said...
> I tried running with a rotated computer monitor last night and to my suprise
> the red color disappeared. At first I thought it was a software problem,
> but then I picked up the monitor and rocked it side to side. When it was in
> normal landscape mode the colors were fine. When it was on its side the
> color mix was decidedly purple and green.
>
> Is this expected? If so, are there certain monitors that do not behave this
> way?

This is normal - monitors are very sensitive to the Earth's magnetic
fields, and as you rotate the monitor you may find that the electron
guns don't align properly, creating discolored areas.

Degaussing the monitor after you've moved it into the postion you want
usually helps, but not always. Sometimes you may need to move the
physical location of the monitor (a few inches to the left or right,
forward or backward) to find the "sweet spot" that gives you the best
color clarity.

For computer monitors, you usually degauss it by an onscreen menu
selection or by turning the monitor on and off. Note that it may take
several degaussings and a few days for the monitor to "settle."

--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

Kevin Steele wrote:
> John Leveille thought about it a bit, then said...
>>I tried running with a rotated computer monitor last night and to my suprise
>>the red color disappeared.>

> This is normal - monitors are very sensitive to the Earth's magnetic
> fields, and as you rotate the monitor you may find that the electron
> guns don't align properly, creating discolored areas.

I agree that this is normal but I disagree that the earth's magnetic
field is the cause. If that were the case then the direction your
screen faces and the angle of your mount would also cause this effect IMHO.

I believe it happens because the components are mounted specifically for
nearly upright viewing. Placing the monitor on its side places stress
on the components (probably the tube). If you were to open your monitor
case and make sure all components were securely mounted in your desired
viewing position I think you could fix the problem.

Arcade monitors come to mind - they are mounted every which way in
cabinets. It would be an interesting experiment. Anyone done it?
 
Archived from groups: alt.games.mame (More info?)

usenet thought about it a bit, then said...
> Kevin Steele wrote:
> > John Leveille thought about it a bit, then said...
> >>I tried running with a rotated computer monitor last night and to my suprise
> >>the red color disappeared.>
>
> > This is normal - monitors are very sensitive to the Earth's magnetic
> > fields, and as you rotate the monitor you may find that the electron
> > guns don't align properly, creating discolored areas.
>
> I agree that this is normal but I disagree that the earth's magnetic
> field is the cause. If that were the case then the direction your
> screen faces and the angle of your mount would also cause this effect IMHO.

That's exactly what happens - my Wells-Gardner D9200 arcade monitor
showed more color purity issues when it was sitting upright on my
workshop bench, but if you tilted it slightly, the color distortions
went away.

Same with my Betson monitor - turning it just a few inches would change
the color purity of the screen.

> I believe it happens because the components are mounted specifically for
> nearly upright viewing. Placing the monitor on its side places stress
> on the components (probably the tube). If you were to open your monitor
> case and make sure all components were securely mounted in your desired
> viewing position I think you could fix the problem.

The component mounting isn't the problem - a PC monitor actually has
higher tolerances for the electron guns, which is why you don't see any
color purity issues unless the monitor is _really_ moved from the
expected orientation (i.e., moved to it's side).

Once you move a monitor, you're always supposed to degauss it. In fact,
that's why PC monitors automatically degauss each time you turn them on.
It allows them to "reset" their internal magnetic field so that the
electron guns aim correctly (the guns are aimed using magnetic fields).

> Arcade monitors come to mind - they are mounted every which way in
> cabinets. It would be an interesting experiment. Anyone done it?

Yup. (see above ;-)

--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

Hi Kevin,

> Once you move a monitor, you're always supposed to degauss it. In fact,
> that's why PC monitors automatically degauss each time you turn them on.
> It allows them to "reset" their internal magnetic field so that the
> electron guns aim correctly (the guns are aimed using magnetic fields).
>> Arcade monitors come to mind - they are mounted every which way in
>> cabinets. It would be an interesting experiment. Anyone done it?

I recently put a 21" PC monitor (mounted vertically) in my cabinet and
noticed that there are some impurities that do not disappear even with the
built in degauss. The blue is perfect, but the red had a faded spot in the
lower left corner and the green has a couple of spots off to the right edge.
Do you think *really* degaussing using a degaussing tool will help? I've
tried to power the monitor on/off every 15-20 minutes to activated the
degauss, and this helps, but hasn't eliminated it so far...

Thanks,

SA Dev
 
Archived from groups: alt.games.mame (More info?)

SA Development thought about it a bit, then said...
> Hi Kevin,
>
> > Once you move a monitor, you're always supposed to degauss it. In fact,
> > that's why PC monitors automatically degauss each time you turn them on.
> > It allows them to "reset" their internal magnetic field so that the
> > electron guns aim correctly (the guns are aimed using magnetic fields).
> >> Arcade monitors come to mind - they are mounted every which way in
> >> cabinets. It would be an interesting experiment. Anyone done it?
>
> I recently put a 21" PC monitor (mounted vertically) in my cabinet and
> noticed that there are some impurities that do not disappear even with the
> built in degauss. The blue is perfect, but the red had a faded spot in the
> lower left corner and the green has a couple of spots off to the right edge.
> Do you think *really* degaussing using a degaussing tool will help? I've
> tried to power the monitor on/off every 15-20 minutes to activated the
> degauss, and this helps, but hasn't eliminated it so far...
>
> Thanks,
>
> SA Dev

Actually, yes, I think a manual degaussing tool will help - I've had to
use my manual degausser on both of my arcade monitors after I've moved
them to remove color impurities. The built-in degausser will probably
work, but it may take time (read: weeks) for the new orientation to set.

Degaussing may not eliminate all the color impurities, though - I've
found that if I put my arcade cab in certain spots in the room I get a
faded red area, no matter how much degaussing I do. Move the cab 3
inches to the left or rotate the cab about an inch, however, and all is
well.

Things that can also affect the screen also include power cables in the
walls or light fixtures. It's a bit of "voodoo electronics" to get it
all worked out.

--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

Hi Kevin,

> Actually, yes, I think a manual degaussing tool will help - I've had to
> use my manual degausser on both of my arcade monitors after I've moved
> them to remove color impurities. The built-in degausser will probably
> work, but it may take time (read: weeks) for the new orientation to set.

I got you. How do you degauss manually? I don't have an official
degaussing tool., but I do have one of those bulk erasers I read could also
be used. Do you have any links to a degaussing page?

> Degaussing may not eliminate all the color impurities, though - I've
> found that if I put my arcade cab in certain spots in the room I get a
> faded red area, no matter how much degaussing I do. Move the cab 3
> inches to the left or rotate the cab about an inch, however, and all is
> well.
> Things that can also affect the screen also include power cables in the
> walls or light fixtures. It's a bit of "voodoo electronics" to get it
> all worked out.

I have power cables running in my cabinet of course, do they cause issues
too? I will say that the impurities are about the same when the monitor was
in the cab vs out of the cab (I had the monitor positioned in the same
position verical at an angle even when out of the cab).

Thanks,

SA Dev
 
Archived from groups: alt.games.mame (More info?)

SA Dev thought about it a bit, then said...
> Hi Kevin,
>
> > Actually, yes, I think a manual degaussing tool will help - I've had to
> > use my manual degausser on both of my arcade monitors after I've moved
> > them to remove color impurities. The built-in degausser will probably
> > work, but it may take time (read: weeks) for the new orientation to set.
>
> I got you. How do you degauss manually? I don't have an official
> degaussing tool., but I do have one of those bulk erasers I read could also
> be used. Do you have any links to a degaussing page?
>
> > Degaussing may not eliminate all the color impurities, though - I've
> > found that if I put my arcade cab in certain spots in the room I get a
> > faded red area, no matter how much degaussing I do. Move the cab 3
> > inches to the left or rotate the cab about an inch, however, and all is
> > well.
> > Things that can also affect the screen also include power cables in the
> > walls or light fixtures. It's a bit of "voodoo electronics" to get it
> > all worked out.
>
> I have power cables running in my cabinet of course, do they cause issues
> too? I will say that the impurities are about the same when the monitor was
> in the cab vs out of the cab (I had the monitor positioned in the same
> position verical at an angle even when out of the cab).
>
> Thanks,
>
> SA Dev

Here's where I got my degausser:

http://mcm.newark.com/NewarkWebCommerce/mcm/en_US/endecaSearch/partDetai
l.jsp?SKU=72-790&N=4

or http://tinyurl.com/4m74u

They've got two:

http://www.newark.com/product-details/text/mcm/html/72-785.html

Hope this helps! (Oh, and I don't think the power cords inside the cab
will be a problem, but your speakers might, depending on how close they
are to the tube.)
--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

SA Dev thought about it a bit, then said...
> Hi Kevin,
>
> > Here's where I got my degausser:
> > http://mcm.newark.com/NewarkWebCommerce/mcm/en_US/endecaSearch/partDetai
> > l.jsp?SKU=72-790&N=4
> > or http://tinyurl.com/4m74u
>
> That looks nice, what is your technique on degaussing? I've read you can as
> easily mess it up more than fix it if you don't know what you are doing...
>
> Thanks,
>
> SA Dev

I'll have to videotape my "degausser dance" sometime, perhaps when I'm
not quite sober.

Basically, you start about 6-8 feet back from the tube and hold the
degaussing ring out in front of you. Turn it on, start slowly waving it
in large circles, and walk slowly towards the tube.

Once you're about 18 inches away, start backing up, all the time slowly
waving the coil in a large circle. Once you're back to about 6-8 feet
away, turn off the degaussing coil.

Like I said, "voodoo electronics" ;-)

--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

Dead_Dad,

> The key word here is *slow*. Go too fast and you will 'freeze the
> instantaneous intensity of the 50/60 Hz AC magnetic field variation
> into the ferrous components of the CRT'. (i.e. You may make the problem
> worse.)

How slow is slow enough? 6 inches per second?

Thanks,

SA Dev
 
Archived from groups: alt.games.mame (More info?)

Dead_Dad,

Also, can I use a bulk eraser to do this? It is a radio shack high power
bulk eraser 120v 8.5A.

Thanks,

SA Dev
 
Archived from groups: alt.games.mame (More info?)

SA Development wrote:
> Dead_Dad,
>
>
>>The key word here is *slow*. Go too fast and you will 'freeze the
>>instantaneous intensity of the 50/60 Hz AC magnetic field variation
>>into the ferrous components of the CRT'. (i.e. You may make the problem
>>worse.)
>
>
> How slow is slow enough? 6 inches per second?
>
> Thanks,
>
> SA Dev
>
>

2ips is good, though there isn't any hard-and-fast rule that *I* know about.

--
Thnik about it!
Dead_Dad
 
Archived from groups: alt.games.mame (More info?)

Dead_Dad thought about it a bit, then said...
> SA Development wrote:
> > Dead_Dad,
> >
> >
> >>The key word here is *slow*. Go too fast and you will 'freeze the
> >>instantaneous intensity of the 50/60 Hz AC magnetic field variation
> >>into the ferrous components of the CRT'. (i.e. You may make the problem
> >>worse.)
> >
> >
> > How slow is slow enough? 6 inches per second?
> >
> > Thanks,
> >
> > SA Dev
>
> 2ips is good, though there isn't any hard-and-fast rule that *I* know about.

Best thing I can suggest is to do the "degaussing dance" with the
monitor on, and watch the colors on the screen. With a bit of practice,
you can see if what you are doing is removing the color impurities, but
it's a bit like trying to read tea leaves while on LSD.

In other words, use the force, Luke...(it's as much gut feeling as
anything else ;-)

--
Kevin Steele
RetroBlast! Retrogaming News and Reviews
www.retroblast.com
 
Archived from groups: alt.games.mame (More info?)

SA Development wrote:
> Dead_Dad,
>
> Also, can I use a bulk eraser to do this? It is a radio shack high power
> bulk eraser 120v 8.5A.
>
> Thanks,
>
> SA Dev

You can try, but I can't guarantee that it will do a good job. Talk to
a local TV repair shop about borrowing their degausser for an hour or so.

--
Thnik about it!
Dead_Dad
 
Archived from groups: alt.games.mame (More info?)

John Leveille wrote:
> I tried running with a rotated computer monitor last night and to my suprise
> the red color disappeared. At first I thought it was a software problem,
> but then I picked up the monitor and rocked it side to side. When it was in
> normal landscape mode the colors were fine. When it was on its side the
> color mix was decidedly purple and green.
>
> Is this expected? If so, are there certain monitors that do not behave this
> way?
>
> Thanks,
> John
> --
> "Nature and nature's laws lay hid by night
> God said, "Let Newton be," and all was light. -- Alexander Pope
>

So a couple days later I tried running the emulator again then the image
would not display properly (the monitor is back in the normal
orientation now). Instead of seeing the discolored, but otherwise
normal image I saw something that looked scrambled -- almost like the
monitor was being driven at the wrong refresh rate. It reminded me of
an oscilloscope display where the image is frantically vibrating around
the screen in a zig-zag fashion. Now, a couple days after that, I can't
get the emulator to show any image. It runs, but I get a blank screen.
When I hit the escape button the vantage emulator exits and returns to
the dos prompt with the standard 60 FPS message. So it appears that
vantage is running normally, but my display has degraded to the point of
blackness.

I have swapped the video card for a different one and I still get the
same behavior. I have not flashed the BIOS, but I am thinking about it.
My question at this point is: Did I break the monitor by rotating it?
That seems far-fetched that simply rotating it could break it. Also,
I am not even sure that something is wrong with the monitor, especially
because it works just fine in VGA mode. I can run character-cell based
DOS programs like norton commander just fine.

Is there any chance that vantage could mess up a monitor with some
unkind refresh rate? I never ran anything, but default options.

I also tried running DOS mame and that just hangs.

Thanks,
John
 
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