[Coco] CoCo 3 to RBG...

[Steven Hirsch]

On Wed, 20 Jul 2011, gene heskett wrote:

> On Wednesday, July 20, 2011 01:00:14 PM Steve Batson did opine:
>
>> Steve,
>>
>> Can you provide details on building your 2 chip circuit to get it
>> working?
>>
>> I received mine this week, built cables to Map Coco 3 RGB signals to the
>> on board 8 pin connector as they describe. The board powered fine, I
>> can access it's menu and functions, but no Coco output. Just a green
>> screen, but I don't think it's Coco output though. Coco works fine with
>> composite  out to TV.
>>
>> Any help will be appreciated!  :)
>
> This is going to be best troubleshot with a decent scope, only that can
> give you a definitive answer.
>
> Oh Wait, you said the 8 pin connector?  Humm, I may be half a bubble off
> here, but ISTR reading in the excruciatingly fine print (I had to drag out
> an old projector lens & use it for a magnifying glass to read that teeny
> little booklet) that the 8 pin connector only handles 31khz & up sources,
> so I had not considered doing anything but stuffing the coco's signals into
> the adjacent DB15, which claims to work down to 15 khz, and which means one
> must pay attention to the pinout of the 10 conductor cable from the coco as
> to where it goes in the DB15.

Where in the manual does it say that?  The one I'm looking at claims that 
15Khz. video can be applied to P3 (The large pins on the left), P11 (8-pin 
SIL) or P12 (HD15).  Since P3 appears to bring out only the composite sync 
input I never tried it.  I can tell you that H+V on P11 never worked for 
me.  I made the (perhaps erroneous) assumption that the H and V pins on 
the HD15 were connected to the same circuit nodes as H+V on P11.  But you 
know what they say about "assume" :-).

I've never been able to get mine to work with H+V sync on a 15Khz. signal. 
I wrote to their tech support and recall being told that it wasn't 
intended to work with H+V at that horz. freq - only composite sync.

Steve


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