A while back I answered a ‘free old computers to good home’ ad on CL and ended up with a Macintosh Color Classic that needed recapped. (http://www.retroadventures.net/recapping-a-color-classic/) I recapped the board and his machine was very stable but all too slow to really use for much.
I started looking into the best way to max out the Color Classic and what I found out was there were all sorts of hacks that you could do to this computer to replace the logic board with a newer, faster, more-capable board. CCII, Mystic, Takky, etc. Some of these are just as simple as swapping the board (CCII) and others required some pretty major surgery. Or at least, surgery that may be hard to undo if you changed your mind. After using the CC in it’s stock configuration for a few months, I decided to go for the Mystic upgrade hack.
To do this, I needed to source a logic board from an LC (or Performa) 575 computer. After having a wanted ad up online for a few weeks, I was able to buy one from a user in Singapore. This board came to me in great shape with 36mb RAM and some VRAM as well. I cleaned the board up a bit, did some basic testing and decided that I would put off recapping it long enough to perform the mod and make sure everything was going to work.
I did some research and found an excellent site that details how to do these modifications at powercc.org. This site shows you complete walk-throughs on each of these upgrades and takes all of the guess work out of performing the modifications. The modification that I needed to do was to remove the power supply board, sometimes called the analog board, cut some traces on the bottom side of this board, and solder some jumpers in. All of this will change the voltage going to the video portion of the board, in order to support the VGA resolution of 640×480. By default, the Color Classic board is setup for 512×384, which the LC575 board does not support. You can modify the LC575 logic board to support the lower resolution, but that seems a bit backwards, doesn’t it?
The guide on powercc.org suggested using a Dremel or a small file to cut away the traces on the analog board. My cousin Shane came up with a better, safer idea – a small craft knife. Using the sharp edge, I scored the traces and then turned the knife over and used the back, dull side to scrape the copper trace away at the score mark. Here are some pics of the mods that I performed:
As you can see, first I used a Sharpie to mark the traces that I needed to cut. I used a standard multimeter to check continuity along each step of the way, making sure that the continuity was broken where I cut the traces and then making sure that it was present where I soldered the jumper wires.
Once everything was verified, I reassembled the computer and fired it up.
As you can see, I now had 640×480 VGA graphics on my Color Classic and the LC575 was now stable! Success! I ran a few things to verify stability and then it was time to upgrade the computer to Mac OS 8.1. I wanted to clean install 8.1 and I wanted to install my 4.3GB SCSI hard drive that I previously could only use as an external drive, as Mac OS 7.5 will not boot from such a large volume.
All of this proved to be quite a chore. I installed the 4.3GB drive into the internal drive location in the machine – easy enough. Now to boot up and install 8.1… I have a SCSI CDROM drive, but it is an NEC model not an Apple branded one and the computer refused to boot from it.
I installed the old 1.2GB drive with 7.5.5 into the external HD enclosure and booted from it. It could see the 4.3GB drive and the CDROM drive. It could not however, read the CD of Mac OS 8.1 because it is an HFS+ formatted volume and HFS+ support is not present in 7.5.5… Damn!
I found a download link for the floppy disk version of 8.0 (all 29 disks of it!) and the ISO image for the 8.1 update. I copied them using AFP to my RPi which runs netatalk and then used AppleTalk serial to copy all of this to the 4.3GB drive in Mystic CC. I then mounted every 8.0 disk image at the same time and ran setup. It was slowed down a bit with all of those images mounted together, but it was still usable. Once setup was complete, I rebooted, then mounted and ran the 8.1 update. Whew! That took a bit of time! But it is now complete. And the results are really great.
This is a really fun hack that is well worth it if you can come up with the LC575 logic board. I’d say that the risk is fairly minimal if you have some basic soldering skills and if you are capable of doing some basic continuity testing. Be patient and take your time and you should be able to perform the 640×480 VGA mod on your CC analog board.
So far, my best test of this upgrade is running Ultimate Doom. I played the game in full screen mode for over an hour and the computer was rock solid and very reliable.
In the future (this weekend) I plan to use my new 3d Printer to print out a backplate for the Mystic modded Color Classic. I found the STL file on 68kmla.org via this thread. I’ll update this post after the part is printed and installed.
That’s all for now. On to the next project!