Path: utzoo!attcan!uunet!comp.vuw.ac.nz!actrix!Roger.Sheppard
From: Roger.Sheppard@bbs.actrix.gen.nz
Newsgroups: comp.sys.atari.st.tech
Subject: Re: NEC 3D and IB Multisync switchbox
Message-ID: <1991Jan23.130832.9011@actrix.gen.nz>
Date: 23 Jan 91 13:08:32 GMT
References: <1991Jan18.220827.4568@ecst.csuchico.edu> <1798@mwca.UUCP>
Sender: Roger.Sheppard@actrix.gen.nz (Roger Sheppard)
Organization: Actrix Networks
Lines: 42

<1991Jan22.195929.23721@ecst.csuchico.edu>
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Organization: Actrix Information Exchange, Wellington, New Zealand
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Comment-To: ekrimen@ecst.csuchico.edu
 
In article <1991Jan22.195929.23721@ecst.csuchico.edu>
ekrimen@ecst.csuchico.edu (Ed Krimen) writes:
> bill@mwca.UUCP (Bill Sheppard) writes:
> 
> - I'm surprised a power supply is needed.
> 
> I am too, but just as long as the damn thing works. :^)  Actually a 
> friend of mine who has a 3D connected to his Amiga mentioned that a 
> power source may be needed because of something funky (<-- good term, 
> huh? :^) with the 3D's output.  I got the box used and I thought the 
> port where the power supply goes in was a headphone jack.  I opened 
> up the box and it didn't look like it was going to any audio source. 
> 
> A friend of mine also has the 1302 and he doesn't need a power supply 
> for his switch.
> 
> -- 
>          Ed Krimen  ...............................................
>    |||   Video Production Major, California State University, Chico
>    |||   INTERNET: ekrimen@ecst.csuchico.edu  FREENET: al661 
>   / | \  SysOp, Fuji BBS: 916-894-1261        FIDONET: 1:119/4.0
 
I have read somewhere that the ST puts out a short Frame sync pulse
that does not lock some monitors in the Mono Mode, so they put in a 555
timer IC, this could be what the P.S.U. is for, also I have read that
the later versions of the NEC 2A do work on a Atari, Note the Atari only
has 2 scan modes, similar to CGA/VGA but with Analog inputs, anothere
thing that is often forgoten is that the RGB voltages are 1 volt pk-pk
and some monitors can only take 0.75 volts pk-pk, so to get this voltage
down, just fit 22 ohm resitors in the RGB lines at the monitor end of
the cable...
 
-- 
Roger W. Sheppard   85 Donovan Rd, Kapiti New Zealand...