[ale] OT: Question regarding whining monitors (for you EEs out there)

[zeb]

On Monday 21 March 2005 02:57 pm, James P. Kinney III wrote:

My two cents:  There are loose laminations in the flyback transformer.

Forty years ago I could tell if a television was turned on without seeing the 
picture tube.  The horizontal flyback in TV sets operates at 15,750 cps (this 
was in the days before Hertz),  The induced currents cause the laminations to 
vibrate, producing a whistle at 15,750.  I tested my hearing with an audio 
oscillator and my "hi-fi" system (I told you it was a while ago).  I could 
hear at least to 17,000 cps.  Whether my speaker cut out or my hearing cut 
out was not determined.  I remember hearing Galton whistles at 23,000 cps in 
Psychology class in college.

Sometimes the laminations can be tightened by tightening the mounting screws.  
Perhaps it could be replaced.  A flyback transformer from a similar set with 
a defective CRT?  Perhaps some sort of "damper" (epoxy?) might stop the 
vibrations.

I don't think capacitors or solid state devices are to blame.

Please, let us know the problem and the fix.

Zeb


> On Sun, 2005-03-20 at 23:47 -0500, Jeff Hubbs wrote:
> > Bad flyback transformer?
>
> Nah. Transformers don't run at high frequecies. It is likely a bad
> capacitor about to blow.
>
> > On Sun, 2005-03-20 at 23:16 -0500, John Wells wrote:
> > > Guys,
> > >
> > > I have an Apple eMac that has monitor issues (see older threads in
> > > which I've mentioned it).  Most of the the time everything works fine,
> > > but if I leave it on for 15+ minutes or so on average, the monitor
> > > begins to emit a high-pitched whine that seems to grow in intensity
> > > over time...to the point that I'd rather jab an ice pick into my temple
> > > than to sit at it for very long.
> > >
> > > I'm preparing to take it to the only authorized support center here in
> > > Greensboro...CompUSA, but want to be fully wearing my BS armor before
> > > going in.  In my experience, these guys will throw out any random
> > > explanation, assuming you're a DAU who doesn't know better.
> > >
> > > Can someone explain what might be the likely cause of this?  I've seen
> > > older monitors do this in the past, but don't really have a handle on
> > > what causes it.
> > >
> > > Thanks for any information you can provide.
> > >
> > > John
> > > _______________________________________________
> > > Ale mailing list
> > > Ale at ale.org
> > > http://www.ale.org/mailman/listinfo/ale
> >
> > _______________________________________________
> > Ale mailing list
> > Ale at ale.org
> > http://www.ale.org/mailman/listinfo/ale