Date: Thu, 26 Dec 1996 04:05:31 +0100 (MET) From: grog@lemis.de To: abbailey@netcom.ca (ANDRE BERNARD BAILEY) Cc: questions@FreeBSD.org (FreeBSD Questions) Subject: Re: Frying your monitor Message-ID: <199612260305.EAA26699@freebie.lemis.de> In-Reply-To: <199612160608.BAA27712@tor-srs1.netcom.ca> from ANDRE BERNARD BAILEY at "Dec 16, 96 01:08:29 am"
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ANDRE BERNARD BAILEY writes:
> Hi,
>
> I bought a FreeBSD from a book shop and while reading I found out that
> I can fry my monitor. I am new to unix os and would like to know what
> should I do not to fry my VGA monitor as I am at the stage where I am
> ready to install.
Well, why don't you read what the book says? Here it is (page 116):
How to fry your monitor
Remember that a monitor is just a glorified TV? Well, one of the
design constraints of real TVs is that they have only a single
horizontal frequency and only a single vertical frequency. This
simplifies the hardware design considerably: the horizontal
deflection uses a tuned circuit to create both the deflection
frequency and the high voltage required to run the tube. This
circuit is comprised of a transformer (the line transformer) and a
condenser. Run a line transformer even fractionally off its
intended frequency and it will run much less efficiently and use
more current, which gets converted to heat. If you run a
conventional monitor off spec for any length of time, it will burn
out the line transformer.
You don't have to roll your own X configuration to burn out the
monitor: ten years ago, the standard display boards were CGAs and
HDAs, and they had different line frequencies and thus required
different monitors. Unfortunately, they both used the same data
connector. If you connected an HDA (18.43 kHz line frequency) to a
CGA monitor (15.75 kHz, the NTSC line frequency), you could expect
smoke signals within a few minutes.
Modern PC monitors no longer use line transformers, and there are
few of them which can't handle at least a range of line frequencies,
but this doesn't mean you can't damage them--you'll just burn out
something else, frequently the power supply. In addition, just
because the monitor displays correctly doesn't mean that it is
running in spec. I have a rather elderly Eizo 9500 (called Nanao in
the US) which has three frequency ranges: (exactly) 31.5 kHz, 48 to
50 kHz, or 64 to 78 kHz. In fact, it will display at any frequency
between 48 and 78 kHz, but if it were run at 57 kHz for any length
of time, I would be in for a hefty repair bill. The moral of the
story:
Never run your monitor out of spec. If your display is screwed
up, there's a good chance that the frequencies are out, so turn
off the monitor.
Monitors aren't the only thing that you can burn out, of course. If
you try hard, you can also burn out chips on some display boards by
running them at frequencies which are out of spec. In practice,
though, this doesn't happen nearly as often.
> The # on the cdrom is ISBN 1-57176-079-2
Really? Unfortunately, that doesn't identify the book uniquely, but I
haven't seen one with this ISBN. I'm assuming that you have "The
Complete FreeBSD", but my copy has the ISBN 1-57176-159-4.
Greg
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