NTSC Snes RGB to Commodore 1084 6 pin analog RGB (sync issue!)

[dsimpson410]

I just picked up a Commodore 1084 from Craigslist with the intention of modding my consoles and using the monitor as my RGB display. I got home and noticed that my new-to-me monitor doesn't have the 9-pin D-Sub connector that would have made my modding experience a lot more headache free. Instead it only has the 6-pin DIN connector. I looked up the pinouts for the 1084 6-pin and noticed that it only accepts separate horizontal and vertical sync signals, not one composite sync signal. It does have the space on the main board for the SCART connector, and as I understand it SCART does accept one single composite sync signal.

So my questions are these:

Can I still wire my NTSC Snes up to the 1084?
If so, where would the composite sync line go?
To the horizontal sync? the vertical sync? Or elsewhere on the board where the composite sync would have gone for the SCART connector?
Or do I need an LM1881 chip?

Any help with this would be GREATLY appreciated.

[Midori]

You can try to connect composite sync to the horisontal sync input. No harm done if it doesn't work.

If that doesn't work then you will have to use a LM1881, that should  definitely do the trick. There are consoles that doesn't output composite sync aswell and just composite video. The LM1881 would be useful for these machines aswell(Playstation for example).

[dsimpson410]

Thanks! I'll definitely try it.

I did come across something weird while trying to figure this out. On the pinout for the Amiga to 1084 cable, I noticed that the Amiga outputs composite sync  ALONG WITH horizontal and vertical sync, yet at the RGB analog port on the monitor it connects the composite sync to the horizontal sync line ONLY. This makes me think that your suggestion will work.

Off topic: Do you have any idea why Amiga did this?

[Midori]

Not really :-) Probably just to make it as compatible as possible with different RGB monitors. The Amiga can aslo output digital RGB, and that almost always require separate H and V sync so it could be made for that aswell...

But most analog RGB monitors can accept composite sync on the H input.

[dsimpson410]

Thanks for your help! Next stop, Radioshack 

[dsimpson410]

Just finished my mod and wanted to post my confirmation that the 1084 will accept composite sync on the horizontal sync line. Thanks again for your help!

Next mod: Sega Saturn.