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Re: Noise from monitor...



* Donald R. Spoon (dspoon@astcomm.net) [020816 20:06]:
> Hall Stevenson wrote:
> >* Ron Johnson (ron.l.johnson@cox.net) [020816 16:56]:
> >
> >>On Fri, 2002-08-16 at 15:00, Hall Stevenson wrote:
> >>
> >>>After one of my XFree86 4.x upgrades, my HP Ergo 1280 (17", model
> >>>D2840A) monitor started making a "noise". Sometimes it's a continual
> >>>sound, other times it's occassional. Whenever it occurs, it's _VERY_
> >>>annoying. I'm at a loss as to how to describe the sound... I guess it's
> >>>just a medium to high-pitched tone, sorta the "white noise" kind. Anyone
> >>>know what I mean ??
> >>>
> >>>This does not occur with MS Windows, so it probably an XFree86-related
> >>>problem. My XFConfig-4 file has no modeline info as I think this was
> >>>removed starting with X 4.x. After sending this message, I'll restart X
> >>>and log the messages and look for anything interesting...
> >>>
> >>>Has anyone ran into anything similar ?? If so, how did you solve it ??
> >>
> >>X isn't configured correctly, and I think this is damaging your
> >>monitor.  Do you have any backup copies of XFConfig-4?
> >
> >
> >Go figure... Since posting my message, the monitor hasn't made that
> >"noise" yet !!
> >
> >I still think I'll reconfigure X and use the "simple" option when it
> >asks about my monitor. I trust it will use very safe HorizSync and
> >VertRefresh numbers.
> >
> 
> This is probably too late if you re-configured, but chances are you are 
> inducing an eddy-current in a metalic object from the magnetic fields 
> around the deflection coils AND the frequency just happens to be at the 
> object's natural resonance.  Simply put, you have a very expensive, 
> single frequency loud speaker <grin>.  This can be a "bad" thing if the 
> resonant object happens to be inside the CRT, but normally it is just a 
> nuisance.  Finding what is vibrating can be a PITA...  If it is still 
> under warranty, it might be worth while checking with the MFGR to rule 
> out a loose element in the CRT, especially if you are operating it 
> within the published limits.

Huh ?? :-)

It's not under warranty anymore so I'll have to find some sort of
"workaround". 

Speaking of specs, the HP manual says this:

Horizontal Sync:    31-92
Vertical Refresh:   50-150

Using 'dpkg-reconfigure xserver-xfree86' and choosing the "simple"
monitor selection, I pick the 17" monitor option. It uses a value of
30-70 and 50-160, HS and VR. Using the "medium" selection and choosing
1280x960@85hz, it uses value of 30-92 and 50-85.

When I hand-entered the spec values, I get the noise. When I use the
"medium" values, I get the noise. When I use "simple", so far, no noise.
Problem solved ?? Maybe...


Hall



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