Color Classic II Mystic Upgrade with Rev D analog board issues

[Sailcat]

Hello everyone! I haven't found very much documentation or discussion for that matter on how to perform the Mystic upgrade with Rev. D analog board other than this thread discussing the 640x480 VGA mod. The issue being that there's no diode at J78 and J79 which I can isolate pin 20. instead I've dremeled pin 20 from ground and its currently jumpered to pin 24 but I'm getting a rolling image.


I'm pretty new at this so I've been searching google for a vertical hold adjustment but obviously its more complicated than that! My next guess would be to jumper pin 20 to pin 3 since that seemed to work for @dkjones96 to get his sense line to work but I wanted to reach out to you all before I make that step.

I'm open to ideas!

Thank you

 

[Sailcat]

Ah, alright I found this page and I'm on the right track in jumping between 20 and 3 but I need a 4.7 K½ resistor. So parts are ordered and I'll report if it works.

 

[chrisrueckert]

The link above seems to be broken.

 

[Sailcat]

Here's the link:

Illustrated Tour: Upgrade Color Classic Resolution

 

[alexGS]

Here's the link:

Illustrated Tour: Upgrade Color Classic Resolution

Amazing - thanks for providing the link. Hard to believe the monitor/analog board was capable of handling an increased resolution/increased frequency all along! Back at that time, it would really have helped, as some newer software assumed a 640x480 display. I guess that Apple had strict rules about the WYSIWYG displayed size of pixels, and therefore no displays at that time allowed multiple resolutions to be selected for the same display size (that didn’t come until the multisync displays as I recall). The PowerBook 500-series that allowed 640x400 as an alternative to 640x480 simply left unused areas, so the pixel size remained the same (of course).

Except - the Colour Classic did have a different mode for displaying Apple II Card output (280x192) at a pixel-doubled resolution of 560x384 - slightly wider than the 512x384.