Help with Sun video

Tony Duell ard at p850ug1.demon.co.uk
Wed Oct 29 11:28:55 CDT 2008


> >> - Connect monitor directly to workstation with a 13W3 Sync-On-Green
> >> adapter (no passthrough of sync signals):  Works fine.
> >>
> >> - Connect monitor directly to workstation with a 13W3 adapter that brings
> >> out H+V sync:  Works fine.
> >
> > Does this adapater do anything to the green signal? Is it possile that
> > the monitor is still using sync-on-green and ignroing the H and V Syncs
> > from the adapter (if, indeed, they're even active)?
> 
> Not sure what you mean.  If there's sync-on-green, it will be there.  The 

Exactly. I was asking if the adapter somehow separated the sync from the 
'green' and passed on only the 'green' to the monitor (this is 
technically possible, of course).

> second adapter just happens to pass through H&V sync also.  Both work when 
> the monitor is connected to the workstation through them.  These are 

My point is that in both cases the monitor could be using the sync in the 
sync-on-green signal and not using the seaprate H and V sync signals 
provided by the second adapter. In other words whether the adapter 
provides the sync signals might be irrelevant to the monitor, but might, 
somehow, affect the swtich.
> > Does this just connect ot the video port on the switch, or to the
> > keyboard and/or mouse ports as well? It wouldn't suprise me if checking
> > for +5V on, say, the keyboard port was part of the 'I have a computer
> > connected' detection.
> 
> It connects to all of the above. I've already heard from just about 
> everyone (thanks!) that the +5V keyboard power is what it's looking for to 

Right.

> activate the port in the first place.  One of the things I want to run 
> through it is video from one of my Amigas, so it appears I'll need to 
> build up a little 5V supply with a keyboard connector that I can use to 
> fool that port (since the Amiga 1200 has its own keyboard and mouse).

I thought there was a +5V output on at least one of the Amiga connectors. 
But maybe only on some models.

> Sorry.  In all cases I'm using a PC-standard VGA-VGA (HD15M-HD15M) cable.
> 
> I'm starting to suspect that the Belkin converter box may be defective, in 
> that it appears sync _is_ getting through while video is not.  I can't 
> think of any other reason why the monitor comes out of standby and yet 
> displays a black screen.  Will get a scope on it soonish and see what's 
> coming out.

This is an LCD monitor, isn't it? I have little experience of those, but 
I have seen a video projector that would detect a signal will incorrect 
scan rates, but not attempt to display it. Maybe your monitor is similar. 
I would try to measure the H and V sync frequencies. It may be (as your 
other message implied) that the adapter somehow gets the workstation to 
output some scan rate that uour monitor can't handle.

-tony



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