Re: Goodbye AppleDesktopBus

[bpvh@primenet.com (Bradley P. Von Haden)]

dalloff@freenet.columbus.oh.us (Dave Althoff) wrote:

>While there may ultimately be difficulty in obtaining ADB devices
>(not for a while, but we Apple ][ people have to take a decidely
>long-term view of this sort of thing...) if you are looking for
>cables and connectors, that should not be a problem as the
>connectors are the same as those used for S-VHS video.  *THAT*
>will be around at least until 2006.

While the connectors on ADB cables and S-video cables (no such thing
as S-VHS cable) are the same, the wiring inside is not.  Here is an
old post from Derek Taubert from my archives:

    From: derek@slab.isdn.uiuc.edu (Derek Taubert)
    Newsgroups: comp.sys.apple2
    Subject: Re: Desktop case: phase 1
    Date: 28 Jun 1996 00:12:15 GMT
    
    S-Video has two signals which both need individual 75 ohm
    transmission lines.  The other 2 pins are ground, and connected to
    the shielding around the two signals.  So in an S-Video cable you
    have two coax cables, while an ADB cable has 4 individual wires. 
    The shielding of the 75 ohm lines will most likely be isolated
    from each other, so you do actually have 4 separate current paths
    (so it MIGHT work), but the crosstalk and impedance is likely to
    mess up the ADB digital signal.
    
    Just buy the right cable for the job.  I'm sure you can find a mac
    place that sells exactly what you're looking for.
    
    --
    Derek Taubert - http://slab.isdn.uiuc.edu/~derek
    taubert@uiuc.edu - NeXTMail welcome
    * Check out TCP/IP for the Apple IIgs!
    * http://www.winternet.com/~taubert/gstcp.html


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