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Hi everyone,
I have a working Color Classic, have installed an LC575 motherboard, and ResEdited the system file so the Color Classic boots ok. Everything works great. 
However, I want to modify the hardware so that I don't have to edit the system file in the future (it's nothing to ResEdit the system, I just like being able to do install the OS with no software mods). I also want 640x480 at the higher refresh rate.
Question 1 re: High res VGA
To do the 640x480 upgrade, I plan to use this http://colourclassicfaq.com/highres/. However, it does not appear to address the higher load on the capacitors, so I plan to do what this page suggests as well: https://68kmla.org/forums/index.php?%2Ftopic%2F24911-color-classic-vga-mod-questions%2F. Does anyone else have any other suggestions or pitfalls to avoid before I dive in?
Question 2 re: system board mod
If I understand correctly, removing R116 and replacing R109 with a 4.7K ohm resistor as per http://colourclassicfaq.com/mobo/mystic.shtmlmeans I won't have to resedit the system file anymore. Do I even need to do this mod if I do the High res VGA mod?


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  • 4 weeks later...



I am about to do the 575 logic board swap in my Color Classic.  I have a question about doing the ResEdited mod.


So I take it that you slide out the old Color Classic logic board and slide in the 5754 logic board and then boot to your hard drive?  After the system is up and and running you then do the ResEdited mod on the system file?  Is this correct?


Which OS are you running?  I am running 7.6.1





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Hey Jack,

I am running 7.6.1 but I believe you can go to 8 (and maybe 8.1?- wil have to check).


You need to do the ResEdit mod before you boot up using the lc575 board, as otherwise it gives you a bus error. I had a patched system on my external drive and regular system on my internal drive, in case I messed up the patching. Set the Mac to boot off the external drive with the resedited system, power down, slide out the regular system board and put in the lc575 board, and then power back on. The ResEdit steps are pretty easy, so it should then boot off of the external drive. Once you're happy it all works, you can always copy the system folders from the external drive to the internal drive.

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Thanks for the tips. 
I have a external CD SCSI drive.  I have a extra SCSI hard drive.  I can hook up the SCSI hard drive to the where my CD drive is now.  I have a external 12V power supply that I can plug into the the SCSI hard drive to power it up....
I need to load the regedit tool onto the external scsi drive?  I am not sure what a "patched system" is... I guess I load a OS onto my external hard drive. All I am using the external hard drive for is to run regedit and edit the file on the hard drive in my color classic, right?
I think I understand what you have done.  But I am not sure about the patched OS on the external hard drive.....


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Hi Jack,
Here are some notes that may help...
On a working Color Classic with its original motherboard installed, download and unstuff the following file: http://colourclassicfaq.com/files/gusdtmpl.sit
Ensure you have a copy of ResEdit available, along with the gusdtmpl file you downloaded the in the previous step. Put them on your external drive.
Copy your system folder to your external hard drive.  Boot from it. 
Open ResEdit, and open the gusdtmpl (you don’t need to do anything with it, just open it. This adds its resources to ResEdit.)
In ResEdit, open the "System" file in the System Folder on your internal hard drive. 
Open the 'gusd' resources item, and open resource ID 1. Find & open gestalt ID number 99.
Change the boot process from 21 to 10, and save your changes.
Shut down the Color Classic. Power off the external drive. Remove the old system board, insert the new one, and power on the machine. It should boot from the internal drive. Set the internal drive as your start volume.
Taken from


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Have you thought about cutting down a 575 analog board and installing it in your Color Classic?


I have not been able to bring my self to cut up the plastic inside my color classic to do this mod.  But I did pick up a 575 analog board and had it cleaned and re caped just in case. My buddy has a wood working shop.  He has large floor standing band saw.  We installed a metal blade in it.  The 575 board cut like hot butter.  It turned out great.  A clean cut and the board fits.   I am looking at a "parts" Color Classic at the moment.  I thought about buying it and installing the 575 analog board in it.....
How is your project coming along?
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I don't mind cutting up the inside of the machine, but it's unlikely I will find a 575 analog board, and I'm not really looking for one at this point.


Glad your cut came out ok! I'll probably be starting my project in a month or so. A friend of mine is doing the same mod at the same time, so we'll have each others machines for testing if needed.

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