Re: AppleColor RGB lines

[KP <kjpmail@gmail.com>]

On Apr 22, 9:25 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> KP wrote:
> > On Apr 22, 3:09 am, Michael J. Mahon <mjma...@aol.com> wrote:
>
> >>KP <kjpm...@gmail.com> wrote:
>
> >>>Help!  I noticed that there seem to be two tiny bands running up the
> >>>screen of my AppleColor RGB.  They are very, very tiny, but they are
> >>>consistently present.  Seem to be much more obvious when the
> >>>brightness is turned way up.
>
> >>>Is that normal?  Is my RGB hitting its final days?
>
> >>Could you be more specific?
>
> >>What is the orientation of the bands?  Their size and location?  Fixed or
> >>moving, and if moving at what speed?  What color?
>
> >>This could be something easy...or not.
>
> >>-michael  -  NadaNet 3.1:  http://home.comcast.net/~mjmahon
>
> > They are 2 horizonal lines.  They slide up the screen until they hit
> > the top of the screen and then they go back to the bottom of the
> > screen.  The lines are probably spaced about equidistant apart.
>
> > If the background color is dark blue, then the lines probably appear
> > what you might call light blue.  Sort of as though they are moving
> > over each band of the display.
>
> > Thoughts?
>
> The lines you see are noise at a 60Hz repetition rate (AC line
> frequency) getting into the video.  The lack of phase lock between
> the computer's video refresh rate (60Hz) and the AC mains causes
> the lines to drift at constant speed relative to the computer-
> synchronized raster.
>
> You mentioned that you just noticed them.  Have they recently
> appeared, or is it possible they've been there for some time?
>
> I ask, because if you have recently changed the position of the
> monitor or some electrical device around it, that change may
> be responsible for the problem.  If so, try changing things back
> to see if you can isolate the problem.
>
> If that doesn't do it, check the connectors on both ends of the
> video cable.  A poor ground or shield connection could cause
> interference from, say, a light dimmer, to get into the video causing
> the lines.
>
> Let us know if any of this resolves the problem or *changes* it.
>
> -michael
>
> NadaNet 3.1 for Apple II parallel computing!
> Home page:  http://home.comcast.net/~mjmahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."

That must have been it!  I've moved a few things a bit and the lines
appear to either not be there or to be so diminished that I can't see
them...

Thank you all for your help!  Now I'll get back to wondering how in
the world I can figure out a substitute long-term solution for when
the AppleColor RGB finally does die!