Macintosh LC 575 “Mystic” logic board recap, install into Color Classic II chassis

JDW

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Folks, I intend to show @Kay K.M.Mods' amazing craftsmanship on YouTube in less than 1 week. The video he made is pretty amazing. Stay tuned!

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Drake

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I'm excited, I hope there's a Kay cameo — at this point he's like a mysterious shadowy figure!
Those who bare witness to his face are frozen as if struck by lightning, impossibly handsome and rugged doesn't begin to describe a man whose features are envy of the gods!
 
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DeChief

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Oct 17, 2021
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Honestly, I'd rather not mod my 575 motherboard. I prefer to do the Analog Board mod instead to get 640x480.

I did the resistor mod just to see what it was like before modding the analog board for 640*480, and it was definitely too limiting in my opinion. With a 33MHz 68040, you're opened up to a much wider range of games and software that will run smoothly, many of which won't display correctly or in some cases boot at all at 512*384. And it's reversible anyway of course.

I'm assuming you're doing the one that doesn't put as much extra stress on the flyback, is that correct? The one reffered to here as the 68.4V "VGA" mod.

 
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Kay K.M.Mods

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I did the resistor mod just to see what it was like before modding the analog board for 640*480, and it was definitely too limiting in my opinion. With a 33MHz 68040, you're opened up to a much wider range of games and software that will run smoothly, many of which won't display correctly or in some cases boot at all at 512*384. And it's reversible anyway of course.

I'm assuming you're doing the one that doesn't put as much extra stress on the flyback, is that correct? The one reffered to here as the 68.4V "VGA" mod.

There are Hi-res Mod (13 inch) and VGA Mod to display on 640X480, but I'm trying both. Of course, in the case of Mystic, you only need to raise the horizontal sync signal a little, so VGA Mods is OK. The purpose is to increase the horizontal deflection voltage from 60V to 68.5V. Therefore, connect 60V out and 8.5V out in series to obtain the voltage.
You can think of it as the burden on each part of the analog board rather than the burden on the FBT that you are pointing to, but in the case of VGA Mods, it can be used with almost no problem. Of course, recapping is necessary anyway.
 
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