[Coco] Generic VGA adapter

[Glen Hewlett]

On Jan 24, 2017, at 12:46 AM, Barry Nelson <barry.nelson at amobiledevice.com> wrote:
> 
>>>> Steve C. towmater at gmail.com  <mailto: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?
>>> On Jan 23, 2017, at 1:56 AM, Barry Nelson <barry.nelson at amobiledevice.com> wrote:
>>> 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.
>> Steve C. towmater at gmail.com  <mailto:coco%40maltedmedia.com?Subject=Re%3A%20%5BCoco%5D%20Generic%20VGA%20adapter&In-Reply-To=%3CCACAVgyGdLho06%3DfhF1NMm8XAWVoUzP2YOk7h50Ksr36paZhpGw%40mail.gmail.com%3E>
>> Mon Jan 23 23:26:32 EST 2017
>> 
>> 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.
> Sorry to hear that. This is a picture of the one I used: https://hackaday.io/project/7366/gallery#2245eff5259883e5811b6937ed1ff55a <https://hackaday.io/project/7366/gallery#2245eff5259883e5811b6937ed1ff55a>
> All grounds are common. Perhaps that test point does not supply enough current. At pin 16 you should show 1 to 3 volts to ground. Pin 16 is RGB mode select To set RGB input mode, put 1 to 3 volts on this pin. (5 volts via a 100 Ohm resistor will set it at 2.1v due to the 75 Ohm load inside the SCART input device).
> http://martin.hinner.info/vga/scart.html <http://martin.hinner.info/vga/scart.html>
> 
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Hi Steve,

For what it’s worth I to bought the same one pictured in Barry’s link above and it’s working for me.

Cheers,
Glen