[Coco] Generic VGA adapter

[Barry Nelson]

> Steve C. towmater at gmail.com  <mailto:coco%40maltedmedia.com?Subject=Re%3A%20%5BCoco%5D%20Generic%20VGA%20adapter&In-Reply-To=%3CCACAVgyGM899pPQ7RA_99autvnQN8SpJ45y7RKvK9oSGi3a2MZQ%40mail.gmail.com%3E>
> Tue Jan 24 22:47:59 EST 2017
> 
> It is showing +5v after the resistor with no load (unconnected) and close
> to 0v when connected to pin 16. This was the cheapest convertor on Amazon,
> and now that I look at it there are a serious number of "missing" - empty
> SMD pads for diodes, or resistors (I'm not sure what would have been on the
> empty pads) near the SCART connector.
I bet if you measure even before the 100 ohm resistor with it connected you will still get a very low voltage. The normal input impedance of the SCART on pin 16 is only 75 ohm. Many of the 5V test point sources inside the CoCo will NOT provide enough current to drive 1-3 volts on that pin. I strongly suggest you try an alternative 5V source with more current driving capacity before giving up. Keep the 100 ohm resistor inline though. You should measure 1-3 volts. Mine was also one of the cheapest converters I could find on eBay at the time. I use an old phone charger which works well, but any 5V source that will provide at least 250 ma (milli-amps) or .25 amps or 1/4 amp should work. I do not suggest continuing to attempt to draw 5V from your precious CoCo 3 as you could damage the CoCo by doing so from the wrong point. Test points are made to test with a meter, not to supply power to external devices. While is probably is more than possible to draw 5V from inside the CoCo, I do not recommend this path unless you are an experienced electronics engineer and you are SURE of what you are doing.