acl wrote:It looks like many of the pins on the VGA socket are linked and four wires(thin green)go to the driver board. The outputs seem to be driven by discreet transistors and resistors. Knowing Grahams excellent experience in design there must be a very good reason for this.
Well, you'll note that the output circuit in my previous posting is the same idea, there's only one channel, not three as this is monochrome with the RGB monitor inputs simply fed with the same signal. That portion is of no issue, it's basically done. There's quite a few ground pins too, so they all need linking together.
Thanks for the photos Chris, you'll note there's quite a few 150R resistors in parallel to create the 75R
video output impedance, again, well documented on the 'net. Nice to see those old metal-can transistors again, haven't used any in many, many years. I think I have a few kicking around...somewhere...
Where information is vague/conflicting is regarding the two separate H and V sync signals, the whole lot sometimes called RGBHV, five signals in total.
Also thanks for the two links, but as expected they focus on the RGB portion, and the syncs are an afterthought, if mentioned at all.
acl wrote:Every time I build something I always plan to keep a folder with all documentation in it. Unfortunately I never do. Anyway I can't find any of Grahams circuits but I photographed the VGA output area.
I learnt my lesson many years ago, I keep and archive everything and the NAS backs it all up in a RAID array. I'm still hesitant to use cloud storage...plus you need Internet access and that's not always possible.
Steve A.