[comp.sys.ibm.pc] monitor problem

stone@cunixb.cc.columbia.edu (Glenn Stone) (10/12/89)

Advice on this monitor problem would be appreciated.  The text undulates
back & forth.  It only sways a few mm, but it's visually disturbing.  I
tried swapping the monitor (IBM enhanced color display) and also 
swapping the EGA card; it still does it.  It's actually quite nauseating
to watch.  Excuse me, I think I'm going to be sick.

GD Stone
Columbia Univ.

cpcahil@virtech.UUCP (Conor P. Cahill) (10/12/89)

In article <1954@cunixc.cc.columbia.edu>, stone@cunixb.cc.columbia.edu (Glenn Stone) writes:
> Advice on this monitor problem would be appreciated.  The text undulates
> back & forth.  It only sways a few mm, but it's visually disturbing.  I
> tried swapping the monitor (IBM enhanced color display) and also 
> swapping the EGA card; it still does it.  It's actually quite nauseating
> to watch.  Excuse me, I think I'm going to be sick.

Have you tried to move the pc to another part of the room?  Since you changed
monitors and cards, I would guess that the problem is caused by some outside
interference (or possibly the power supply, but since the rest of the
machine is working ok, I would *think* it is not the ps).

Maybe there is a 1.2 Gigawatt generator in the next room (bldg). :-)



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fredex@cg-atla.UUCP (Fred Smith) (10/12/89)

In article <1954@cunixc.cc.columbia.edu> stone@cunixb.cc.columbia.edu (Glenn Stone) writes:
>Advice on this monitor problem would be appreciated.  The text undulates
>back & forth.  It only sways a few mm, but it's visually disturbing.  I
>tried swapping the monitor (IBM enhanced color display) and also 
>swapping the EGA card; it still does it.  It's actually quite nauseating
>to watch.  Excuse me, I think I'm going to be sick.
>
>GD Stone
>Columbia Univ.





Since TWO monitors and video cards exhibit the same symptoms, I would say that 
it sounds as if the monitor is suffering from some kind of magnetic
interference--try moving it to a different position several feet from where
it is now located and see if the symptoms change. If so, then you gotta
figure out what is generating the magnetic fields that are upsetting it.
One thing to try is moving it as far as possible away from the PC box itself.

Another possibility (although I think a rather remote one) is that the line
voltage which is powering the tube is unstable.

good luck!


Fred

press@venice.SEDD.TRW.COM (Barry Press) (10/12/89)

Re your problem of images doing the hula --- you should check two other
possibilities.  One is magnetic interference from some other device -- move
the monitor away from everything you can, and see what happens.  Also, check 
what else is on the AC circuit...

gould@physics.usc.edu (Christopher Gould) (10/12/89)

In article <1954@cunixc.cc.columbia.edu>
stone@cunixb.cc.columbia.edu (Glenn Stone) writes:
	>Advice on this monitor problem would be appreciated.  The text
	>undulates back & forth.  It only sways a few mm, but it's
	>visually disturbing.  I tried swapping the monitor (IBM
	>enhanced color display) and also swapping the EGA card; it
	>still does it.  It's actually quite nauseating to watch.

Your problem is that the power lines carrying 60 Hz 120 V which run
inside of your walls, generate magnetic fields which are not negligible
when current is carried.  It's a sad fact of life these days that most
(dare I say all?) monitors are _not_ magnetically shielded.

The oscillation you are seeing is at the beat frequency between the 60 Hz
wall power and the vertical sweep frequency (which is nominally 60 Hz).
If you look carefully for awhile you should be able to see this beat
frequency change (and perhaps even reverse) since the lines are only
guaranteed to be 60 Hz _on_average_, and not instantaneously.

The solution is to simply move your machine to a different location so
that it is not so near to these current carrying wires in your wall.

Either that or rip up your walls and move the wires.
_________________

Christopher M. Gould - Univ of Southern Calif - Dept of Physics   (213)743-8521
Internet: gould@usc.edu    Bitnet: gould@uscvm    UUCP: uunet!usc!physics!gould

lisbon@vpnet.UUCP (Gerry Swetsky) (10/13/89)

Monitor "wiggle" is generally caused by power supply ripple or
fluctuations.  Why is it happening with TWO monitors?  Look at pins 7,
8 and 9 of your nine pin display connector with a scope and see if
there is fluctuation there.

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karl@ddsw1.MCS.COM (Karl Denninger) (10/13/89)

>Item 6087 (1 resps) by stone at cunixb.cc.columbia.edu on Thu 12 Oct 89 16:26
>[Glenn Stone]    Subject: Monitor problem
>(8 lines)
>
>Advice on this monitor problem would be appreciated.  The text undulates
>back & forth.  It only sways a few mm, but it's visually disturbing.  I
>tried swapping the monitor (IBM enhanced color display) and also 
>swapping the EGA card; it still does it.  It's actually quite nauseating
>to watch.  Excuse me, I think I'm going to be sick.

Is there another monitor in the immediate vicinity?

If so, move it.  I've seen this occur when two systems and monitors are
placed "too close" together.  It's a problem with EMI interferance between
the two systems.

Check the power supply as well for ripple, and in addition check the WALL
for 120V power.  Low voltage will sometimes cause this.

--
Karl Denninger (karl@ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
Public Access Data Line: [+1 312 566-8911], Voice: [+1 312 566-8910]
Macro Computer Solutions, Inc.  "Quality Solutions at a Fair Price"

wek@point.UUCP (Bill Kuykendall) (10/15/89)

>Advice on this monitor problem would be appreciated.  The text undulates
>back & forth.  It only sways a few mm, but it's visually disturbing.  I

My little desk fan will do that to a monitor if it gets within a couple of
feet of it.  Flourescent lights are notorious for magnetic interference, too.

joec@Morgan.COM (Joe Collins) (10/27/89)

I have an OLD Princeton HX-12 Color Monitor. Its CGA
compatible and I bought it before IBM announced their
first color monitor for their original IBM PC.

Its been 'old faithful' all these years but I still wish
to eke out a few more months out of it.

The problem is the BLUE color, it occasionally goes out.
A smack of the hand on the side of the monitor always 
fixes it but thats crude.

Think its as simple as a loose wire? Those I can fix.
If its more complex, then I'm out of luck.

BTW, I don't hear high voltage hissing or smell ozone
that would come with a high voltage leak.

Please email me direct if you have thoughts....

Thanks,
joec@morgan.com