[Coco] CoCo 3 to RBG...

[Steve Batson]

I haven't yet tried moving the wire, haven't had the time. I'm also not 
super happy with my current cable, but I do want to at least verify 
connections and try the gray wire move suggestion. Once I do that, and if 
it doesn't work, I will be waiting to see what Gene and others find. I will 
certainly be willing to build your circuit if all else fails, and hey, I 
may have my new soldering iron by then! ;)

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

From: "Steven Hirsch" <snhirsch at gmail.com>
Sent: Thursday, July 21, 2011 8:23 AM
To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
Subject: Re: [Coco] CoCo 3 to RBG... 

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

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