[rescue] Re: Video Switch?

[Gregory Leblanc]

> From: "Loomis, Rip" <GILBERT.R.LOOMIS at saic.com>
> Date: Thu, 10 Oct 2002 16:14:19 -0400
> To: "'rescue at sunhelp.org'" <rescue at sunhelp.org>
> Subject: RE: [rescue] Video Switch?
> Message: 8
> Reply-To: rescue at sunhelp.org
> 
> > > I'm probably simply looking in the wrong places, but does 
> > > anyone know
> > > where I  can get a video switch box? I have one SVGA 
> > > monitor that I'd
> > > like to share between a pc and the SunPCI in my SunBlade 
> > > 100. I don't need a full blown KVM.
> > 
> > I've had really poor luck with the cheap video switchboxes.  
> > Maybe you'll
> > have better luck.  If you'd like to try one, e-mail me your 
> > address and I'll
> > send you one.
> 
> I'd agree with statements about having really poor luck.  The
> 2-position "turn a switch" A/B video switchboxes show up on
> eBay for ~$10.00 sometimes, or less at the ComputerPro shows
> around here.  They're okay for text-mode stuff but crap for
> higher-bandwidth video.

Unfortunately, these switch boxes can't possible work well, at least
if you're trying to switch (insert name of stupid PC designed video
connector here [is it HD15?]).  Clean video signal requires
predictable impedance levels (hum, I hope I'm using that terminology
right).  The cables used can do this just fine, assuming they have
some shielding and ferrite blocks on them, but everything goes to hell
in the connectors.  Going through one of those manual switchboxes,
you've got at least three cable terminators (both ends between
computer and switch box, and the end of the "embeded" monitor cable).
Add this to the very cheaply made switching mechanism inside, and fact
that there's no shielding on the connector, and the box itself doesn't
provide any, and you've got a pretty sure recipie for disaster.  If
you really want to switch a monitor between two video cards, or a
video card between two monitors, you're really best of getting a
decent "digital" PC KVM, and just using that.  Or, get one of the nice
monitors with multiple inputs.  CTX used to have one with the mac, PC,
and 5-bnc connectors on it.  Too bad the tube sucked.
    Greg