[Coco] Generic VGA adapter

[Glen Hewlett]

Hi Steve,

Are you sure you have the RGB leads to the correct pins on the CoCo 3?  I had them completely backwards at first.  At first I used the info from this picture:
http://www.oocities.org/theother_bob/cocofaq/cocorgb.gif <http://www.oocities.org/theother_bob/cocofaq/cocorgb.gif>

I thought it was a diagram of the bottom of the CoCo3 but it’s the connector’s pins so I had the pins completely wrong.  I found this out by having everything hooked up except the RGB wires to the SCART connector.  Then I tried plugging my SCARt red lead to different pins on the CoCo (I first thought my CoCO 3 was defective) then I found out I was getting my signals from pins 5,7 & 8 from the picture I linked above.  That when I realized I had it all backwards.  You might be using a better picture or know the correct pins, I just thought I’d let you know what I did and maybe you were seeing the same thing.

Cheers,
Glen

Ps	
Just so you know this is a picture of the motherboard and you can see the actual PIN numbers from the top of the board.  Use this info to connect to the proper pins on the bottom of the board/computer and you should be good to go.  http://www.tehkella.net/retro/wp-content/uploads/2015/01/PB230053.jpg <http://www.tehkella.net/retro/wp-content/uploads/2015/01/PB230053.jpg>

> On Jan 23, 2017, at 11:26 PM, Steve C. <towmater at gmail.com> wrote:
> 
> I fear it may be the cheap SCART converter. I have the 100 ohm connected,
> and the grounds are all tied to the coco GND, (unless it is supposed to
> have a totally isolated 5V + ground? I used a pad conveniently marked 5V TP
> on the MB for power) I even went the extra length of using shielded coax
> for the RG and B lines with the shields tied to ground on the SCART
> connector and motherboard.
> 
> On Sun, Jan 22, 2017 at 10:56 PM, Barry Nelson <
> barry.nelson at amobiledevice.com> wrote:
> 
>> *Steve C.* towmater at gmail.com
>> <coco%40maltedmedia.com?Subject=Re%3A%20%5BCoco%5D%20Generic%20VGA%20adapter&In-Reply-To=%3CCACAVgyHesogaf3AYKzUcZYg-4M-p9q%2BAN-TKbenNVJFRrN9WdQ%40mail.gmail.com%3E>
>> *Mon Jan 23 01:03:29 EST 2017*
>> 
>> I built this RGB-SCART-HDMI adapter, but it is seemingly just taking the
>> composite video on pin 20 to HDMI and ignoring the RGB. Any ideas where
>> this went wrong?
>> 
>> One of 3 things is probably wrong.
>> 
>> 1) You did not connect a +5V supply to a 100 ohm resistor to pin 16 as shown in the diagram.
>> 
>> 2) You did not connect the ground of the 5V supply to ground on pins 4,5,9,13,17, and 18.
>> 
>> 3) you got unlucky and got a SCART to HDMI converter that does not support RGB video. Send it back and get a different one. If this is it, let me know as it will be the first time this has happened.
>> 
>> 
> 
> -- 
> Coco mailing list
> Coco at maltedmedia.com
> https://pairlist5.pair.net/mailman/listinfo/coco