Re: Help w/ NEC Multisync 3d and TTL

["Michael J. Mahon" <mjmahon@aol.com>]

Steven Hirsch wrote:
> I'm not sure where else to turn for help with this.  I'm trying to use 
> my NEC Multisync 3d with a variety of older computers that operate at 
> 15.7khz Horz scan frequency - Apple IIgs, Atari ST, Commodore C128, etc.
>
> Unfortunately, I do not have the adapter that NEC offered to convert the 
> captive HD15M on the monitor to 9-pin connectors.  I've scratched my 
> head over the user manual and a fuzzy copy of the service information 
> and still can't make heads or tails out of it.
>
> The service manual lists the following signals as being valid when in 
> TTL (EGA/CGA) mode:
>
> RA GND
> r
> R
> g
> V.D
> H.D
> G
> B
> b
>
> So, what is that trying to convey?  The V and H sync are somewhat 
> obvious, as are R,G,B.  So, what are the lowercase r,g,b? Inverted 
> polarity?  Different levels?

I'd guess shield ground for the R, G, and B coax cables.

You'll also need to know if providing composite sync to one or both
of the sync inputs will work, since Apples only provide composite sync.

> Is "RA GND" just simply ground or is it something else?

I think for your purposes, just considering it a ground is fine.

> Does anyone reading this group have the original adapter?  Are you 
> willing to ring out the connections?
>
> If it will help, I can forward PDFs of the pertinent portions of the 
> schematic on request.

That would remove any ambiguity.  My email address is un-munged.

-michael

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