🚀 go-pugleaf

From article <890626-180453-1234@Xerox>, by "chaz_heritage.WGC1RX"@XEROX.COM:
> Has anyone succeeded in deriving from the ST's RGB output an RGB drive
> suitable for a SCART-input Trinitron? I'm told that the digital RGB from
> the ST has to be attenuated - presumably from 5V to 1V - to match the
> Trinitron's analogue RGB input. However, before getting the soldering iron
> and resistors out I'd be interested to know if anyone else has done this,
> and preferably what values of resistors they used. 
> 
> The ST-SCART cables sold by many computer stores work fine on other
> monitors - the more honest stores say 'Not for Sony'; Computer Express say
> that it'll work, and then refuse to have anything to do with you when it
> doesn't...
> 

What specific Sony monitor are you trying to use?

I've had a Sony CPD-1302 multisync connected to my ST system for more than
two years.  It works fine in both monochrome and color modes.

In general the video characteristics of the ST are:

    color mode

        analog RGB; signal range is 1V
        timing is NTSC compatible

    monochrome mode

        the monochrome video line is an "analog" looking signal with
            the same signal range as the color video lines
        timing is 70hz vertical, 35hz horizontal (???)

    both modes provide negative-going sync (???)

So my switchbox just routes the video lines through voltage dropping resistors
(the 1302 wants 0.6v), and handles video mode switching.  In color mode, the
ST monochrome detect line is left floating, and the RBG video lines are connected
to the monitor.  In monochrome mode, the monochrome detect line is grounded,
and the monochrome video line is connected in parallel to the three monitor
input video lines.

Some other notes on attaching "foreign" monitors to the ST:

    make sure that the provided and expected sync directions match; if they
    don't you will need an inverter.

    unless you have a multi-sync monitor, don't try to do anything with monochrome mode

    don't expect all monitors from the same manufacturer to behave the same.  Around the
    time I first built my switchbox, Computer Shopper had an article on attaching
    a Sony XBR series monitor to the ST.  That circuit was different.

dgc