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Main => Monitor/Video Forum => Topic started by: gonzojoey on April 29, 2008, 05:46:46 pm

Title: Question about CGA to VGA using a Dreamcast converter
Post by: gonzojoey on April 29, 2008, 05:46:46 pm

Is it possible??  :dunno
I'm referring to this post about hacking a Dreamcast to VGA cable to be used on a standard arcade CGA monitor.
http://forum.arcadecontrols.com/index.php?topic=37411.0

What I'm wondering is can I basically do this hack in reverse and hack the DC side of the cable? I'd like to be able to use a VGA monitor w/ my Jamma boards (due to cost and availability of VGA monitors) and this would be a much cheaper solution than buying a CGA to VGA converter for $80 - $120.
I don't have one of these converter cables available to me right now, but I'll be buying one in the next few weeks to play around and see what (if anything) can be done.

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: grantspain on April 29, 2008, 05:59:36 pm

your jamma board output a cga 15khz signal,your vga monitor will be expecting a 31khz signal-without any kind of decoder it will not work

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: gonzojoey on April 29, 2008, 09:37:01 pm

Well, the reason I asked was because some people were able to hack the cable to make the Dreamcast output to a cga arcade monitor instead of a vga monitor. So I guess the conversion process wouldn't work in reverse? Or is this device not really a "signal decoder"?

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: MonMotha on April 29, 2008, 10:06:27 pm

The reason this can be done with Dreamcast VGA boxes when used with a Dreamcast is that the box doesn't actually do any conversion itself.  The "hack" involves telling the Dreamcast to generate signals at either CGA or VGA timings.  It's apparently pin 6 on the connector (according to the docs I have).

Also, just because a device can downconvert, doesn't mean a device works the other way, though with a simple deinterlace (line doubler)/interlacer, the hardware is similar.

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: gonzojoey on April 30, 2008, 08:04:27 am

Thanks guys. I'll keep searching for another way...although it would probably just be easier for me to bite the bullet and pay for a converter. I'll check around through my piles of old PC stuff to see if I might have a CGA monitor hiding somewhere  :P

Thanks again!!

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: StephenH on May 03, 2008, 02:21:48 am

This should do the trick:

http://www.converters.tv/products/cga_to_vga/77.html

Title: Re: Question about CGA to VGA using a Dreamcast converter
Post by: gonzojoey on May 03, 2008, 01:49:48 pm

Thats a little to rich for my blood. For that price, I'll just pick up a refurb arcade monitor from my local guy. I was just looking for a cheap and easy solution since I have so many PC monitors at my disposal.  But Thanks anyways :)!