Seeking an ECL monitor (preferably for a dimple-top Sun base) and Sun 3 Keyboard and Mouse

Michael Engel engel at
Tue Jan 27 14:38:43 CST 2015

On 27 Jan 2015, at 20:15, Ian Finder <ian.finder at> wrote:

> Someone has helpfully offered up a Sun-branded monochrome monitor with two
> BNC inputs- video & sync- on the back.
> I fear, however, that this is a greyscale monitor designed to work with one
> channel on a *color* Sun 3 framebuffer, and not necessarily a monochrome
> ECL output.

The Sun mono monitor has a DB9 input, so this is probably a monitor for a CG3/
CG6 SPARC SBus card (there was also a bwtwo SBus card which provided ECL
output IIRC). It's hard to find a picture of this monitor, I think this one from Wikipedia 
is the BNC type greyscale monitor:

However, it's strange that the monitor has two BNC inputs - the grayscale monitor
was usually driven by the Sync-on-Green signal, so it should require only one BNC
connector. However, I haven't seen a Sun grayscale monitor in almost two decades.

> Can anyone confirm, or is it simply a matter of building a cable?
> If this can be adapted using some similar circuitry to the ECL -> TTL
> adapter mentioned, I might still go for it.

The hardware FAQ doesn't mention the frequencies accepted by the grayscale
monitor. But I think it supports the same as the color monitor, since the 
grayscale simply uses the green (+sync-on-green) signal instead of RGB.

The standard 1152x900 resolution ECL monitor's frequencies are 61.8 kHz 
horizontal and 66 Hz vertical. The color screen also supports a 61.8 kHz/
66 Hz mode, so the frequencies seem to be compatible.

Assuming the ECL-to-TTL converter solution works (will try in two weeks when
I'm back in Germany), generating the analog grayscale signal should be a 
matter of reducing the signal voltage (1 Vpp instead of 5 V) and mixing in 
the H/V sync signals. This circuit by Tomi Engdahl might be a starting point
(the first one it mixes the sync signals):
Mixing this to a sync-on-green signal is described here: (if sync-on-green works with
the monitor).

Beware - I have tried none of these circuits, so checking the voltages and frequencies
at the output before connecting a monitor is highly recommended...

Hope that helps...

-- Michael

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