Help with Sun video

Pete Turnbull pete at
Wed Oct 29 18:46:09 CDT 2008

On 29/10/2008 16:28, Tony Duell wrote:

>> 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.

A lot of LCD monitors do that -- including the two in front of me now.

> 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.

Sun (and SGI) 13W3 connector use some of the pins not otherwise reserved 
for sync as monitor sense pins -- and the permutation of which are tied 
high or low tells some video adapters what resolutions (and hence scan 
rates, sometimes) to use.  So it's possible.  I think it's unlikely, 
though, because most adapters I've seen don't connect those pins in any 
exciting way, and anyway, Suns don't usually change resolution except 
during the boot process.

All I can say is that I've never had much luck with Belkin KVMs on Suns 
and SGIs, or even PCs in some cases, and tend to stick to others that I 
know are less picky.  The best ones I found are cheap Newlink ones.  I 
have one here working happily with a Sun, an SGI, a PC, an Apple Mac, an 
Acorn Archimedes, and a BBC micro (actually it's a 4-way KVM and the SGI 
and Mac are not usually connected to it), without a PS/2 keyboard in 
sight.  Sadly they don't make that model any more :-(

Pete						Peter Turnbull
						Network Manager
						University of York

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