[Coco] CoCo 3 to RBG...

Steve Batson steve at batsonphotography.com
Thu Jul 21 13:54:54 EDT 2011


Gene, All,

This may help somewhat, the PDF is certainly eaier to read then their 
printed manual that came with the board. They have certainly kept info in 
all of this to a bare minimum. Hopefully this helps.

Here's the link to the main info page on that board:
http://www.jammaboards.com/store/cga-ega-yuv-to-vga-converter-pcb-gbs-8220/p
rod_291.html?ccSID285e73f64c04744fc5f33ff68f529742=f7368a10fdefe104fcf2ee966
41c50c9

Here's a link to the basic on-line setup guide:
http://www.jammaboards.com/faq/article/cga-to-vga-video-converter-gbs-8220-p
cb-basic-setup-13.html

Here's the direct link to the PDF of the manual:
http://www.jammaboards.com/arcade_manuals/GBS-8220_CGA_to_VGA_HD-Converter.p
df

----------------------------------------

From: "gene heskett" <gheskett at wdtv.com>
Sent: Thursday, July 21, 2011 10:40 AM
To: coco at maltedmedia.com
Subject: Re: [Coco] CoCo 3 to RBG... 

On Thursday, July 21, 2011 01:35:09 PM Steven Hirsch did opine:

> On Thu, 21 Jul 2011, Steve Batson wrote:
> > No kidding about this getting more confusing as we go. At first, when
> > I didn't get mine working after the first pass, I figured I probably
> > have a bad connection or didn't wire it right. And I haven't had a
> > chance to get back and double check my connections to make sure
> > everything is correct. With the other people here having issues, I
> > know it's not just me ;)
> > 
> > Seems pretty straight forward when you look at the connectors on this
> > board and the CoCo. If the CoCo is not putting out the proper
> > signals/levels for this board, then it's not standard RGB I would
> > think...but it works with the CM8 as well as a Magnavox RGB monitor,
> > so I'm suspecting it is a Standard RGB output requiring just the
> > proper cable to go to the monitor.
> 
> Did you try their alternate connection scheme? If I interpret it
> correctly, moving the gray wire acts to place HSync on the composite
> sync input (while keeping VSync on the VSync in). There must be some
> rationale for them suggesting that and it's worth a try.
> 
> > That said, I'm more inclined to think that the board is the issue and
> > meeting it's requirments is not as obvious as it should be...and the
> > skimpy manual doesn't help matters. My electronics background doesn't
> > include much video, so while I can follow much of what's been said in
> > this thread, I'm not in a position confirm or deny anything that's
> > been said. I am going to keep toying with my setup to see if I can
> > get it working, but I'm also anxious to see what others here find
> > out.
> 
> Well, if the alternate HSync connection does not get you going then it's
> a perhaps an indication that the board doesn't support H+V sync for
> 15.75 Khz. video. To reiterate my experience: I bought my board on
> eBay about a year ago and was never able to get it working with H+V
> sync. I built the little adapter using a quad 2-input XOR chip and it
> provided a great picture. After that was done, I asked the seller to
> contact the factory for clarification. His response was to the effect
> that H+V sync was NOT supported on 15.75Khz. RGB video.
> 
> Let's see what Gene comes up with in his experiements before rushing to
> judgement. I am very far from an expert on video while Gene are one.
> 
> Steve

Nicely putting me on end of the plank, thanks guys. I sent them a msg 
asking for a link to the booklets pdf, and asking what signal polarity it 
expected on the 8 pin connectors sync inputs. I have the 8220 version of 
this board, and it has zero mention of moving the grey wire. Can someone 
elaborate on that while I am looking for a working 48 tpi floppy drive?

Cheers, gene
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