Re: Noise from monitor...
----- Original Message -----
From: Hall Stevenson <hallstevenson@mindspring.com>
To: Debian-User <debian-user@lists.debian.org>
Sent: Friday, August 16, 2002 9:00 PM
Subject: Noise from monitor...
> 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 ??
>
> Thanks in advance
> Hall
>
Check that your upgrade has not altered the refresh rate. Try setting
slower refresh rates and see if it stops - because the longer it carries
on the faster it's destroying something.
The sound may indicate that your line output transformer is breaking
down; is it an old (ish) monitor? It shouldn't happen if the monitor is
being operated within its refresh rate specs, but when things start to
break down the higher refresh rates tend to show problems first as the
components are more stressed.
Reading other people's replies and your replies to their replies
reinforces this conclusion. I think the critical parameter is the
reduction of your max horizontal refresh rate from 92 to 70.
Other less terminal causes: could be nothing more than an accumulation
of dust - take the back off and clean it (don't zap yourself). While
doing this peer closely at the PCB for signs of solder joints breaking
down - a circular crack tends to form separating the lead from the pad
especially around heavy or hot-running components. A bright light and a
magnifier are useful. This is caused by manufacturers deliberately not
putting very much solder on so it breaks down after a few years and
ignorant people buy a new one.
I worked for a few months repairing warranty-returned Samsung monitors.
Apparently they accept a 1% warranty return rate! The joke in the
workshop was that "Samsung" is Korean for "disposable". The Samsung
CQA4147 monitor is a fire hazard. Fortunately most of them have blown up
by now.
Donald R. Spoon <dspoon@astcomm.net> wrote:
>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.
Fraid this isn't very likely. Works for low-frequency (vertical scan)
signals, but I know the noise in question and it's coming from the line
output department: corona discharge or some related phenomemon.
Pigeon
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