Technology and retro computer blog

Macintosh Mystic Colour Classic

A few weeks back I saw a Macintosh Classic advertised for sale on a local site, it wasn't really a model that I wanted but it had a nice M0487 ADB keyboard and mouse which I did want and the price was good so I decided to go an have a look.  While I was speaking to the seller I asked him if he had any other Mac stuff that he want to sell and he brought out a Macintosh Colour Classic with keyboard.  The Colour Classic didn't work but it was in great condition so I made an offer on both machines and got them for a very good price.


On getting the machines home I tried to power up the Colour Classic but there was no activity, I tried all the recommended easy fixes like replacing the clock battery and ensuring the keyboard was properly plugged in.  This model won't boot unless a keyboard is attached because the start button is on the keyboard.  But nothing worked.  On pulling out the logic board it struck me that it was very similar to an LC575 board that I'd picked up the week before.  I got a non-functional LC575 the previous week for $20, I needed a SCSI hard drive and floppy drive for my SE/30 restoration (see posts in archive regarding the SE/30 and LC575 dis-assembly).  So I put the LC575 board into the Colour Classic and it powered up!  It wouldn't load the OS but it went to the start up screen and was clearly functioning.  Quite a lucky coincidence that this board fit this machine and also considering both the Colour Classic and LC575 were non-functional but for different reasons.  The LC575 most likely had a bad power board and the Color Classic had a bad logic board.


On doing some research on the Colour Classic I discovered that upgrading a Colour Classic with an LC575 board is called the "Colour Classic Mystic upgrade".  You've got to like that.  Thanks to some detailed information on the web about the Mystic upgrade, I was able to patch a version of system 7.5 to install on the upgraded machine.  The issue with the OS is related to the screen resolution, the LC575 has a 640x480 resolution whereas the Colour Classic has 512x384.  So you need to patch a version of Mac OS so it thinks it's installing the system on an LC575 with 512x384 resolution.  There is a great website which goes into detail about the Mystic Colour Classic upgrade and they have a guide on how to patch the system for use on the Mystic upgraded machine:

The zip file below contains System 7.5 patched for the Mystic Colour Classic:

Mac Mystic Colour Classic System 7.5

System 7.5 for Mystic Colour Classic


ZIP: (9.56 mb)

Before doing the install I needed to fix the floppy drive. The floppy was in a similar state to the one I extracted from my Macintosh SE/30, see my post about the Sony SuperDrive head spring fix.

The logic board from the LC575 is a drop in replacement for the Colour Classic but the rear connectors don't line up with the back plate from the Colour Classic.  So I adapted the back plate from the LC575 to fit the Colour Classic.  It fits well but I had to drill new holes to hold it on.  I also bleached it with 40vol cream peroxide to get a better colour match.  I was really pleased with the result.  The left picture below shows the original Colour Classic back plate at the top and the LC575 back plate underneath (cut into two pieces).  The second picture shows the LC575 back plate cut down to fit the Colour Classic.  The third and fourth pictures show the finished back plate.


The 4.5v clock battery on the LC575 motherboard was long dead as you'd expect so I replaced it with an "AA" battery holder which takes three batteries.  Each "AA" battery is 1.5v so this makes up the 4.5v required.  It also allows for easy replacement of the batteries unlike the original unit. To finish off this machine I added a PDS ethernet card to allow for easy transfer of software via FTP.  The image below shows the LC575 logic board with "AA" battery holder and PDS ethernet card.

Comments (6) -

  • James (Jack) Honeycutt

    29/04/2016 12:57:56 AM |

    Great photos and text on your Mystic upgrade.  Thank you.

    Two questions....

    1) I have read that one can take a full 68040 CPU and it is a drop in replacement for the CPU on the 575 board.  Do you know if this is true or not?  If so, have you tried it?  Any real world speed improvements?

    2) I have read that one can buy a 128MB memory stick for the 575 board.  I just did so my self.  It cost $19.95 plus $1.00 postage.  I can not tell you if it works or not.  I need to patch a OS and install my 575 card.  The down side is that it takes the CC a *long* time to boot with a 128MB memory stick inside.  But with some OS's, it is possible to turn memory check at boot off.  I do not have the details on this.

    A lot of games and software are available that work just fine with 512 × 384.  Have you ever thought about moving up to 640 X 480?  I am on the fence about it.  Nice job on your CC.

    • Theo

      29/04/2016 9:58:01 AM |

      Hi Jack

      Regarding your first question, I've heard the same thing about upgrading the CPU but I haven't tried it.  Can't see why it wouldn't work.

      Good timing with your second question, I just upgraded my Mystic CC with 64mb of ram.  It previously had 32.  I've heard you can go up to 128mb.  My 64mb upgrade worked fine.  I bought two 64mb 72 pin simms from here:

      I upgraded both my Mystic CC and my LC475.  Both worked fine.  Only problem with the LC475 was that the simm doesn't clip down fully because it's double sided and because of the low angle of the simm slot on the LC475 board.  I was able to get it down far enough so it works ok.  This is not a problem on the Mystic CC board (LC575) board as the simm slot is upright.

      If you can create disks from images, I can supply you with a copy of the Mystic CC patched OS.  I have patched a copy of System 7.5 for use on my Mystic CC.  I'll post the download link on this page later

      • Jack Honeycutt

        30/04/2016 10:42:46 PM |

        I posted to 68MLA a week or two ago asking about the 128 MB SIMM for the 575 logic board.  I was directed to two SIMMs.  They are:

        (if the above link is broken, it is item # 161432070081)


        (and if that link is broken, it is item number 171473465069).

        I ended up buying one stick here:

        I paid about the same - $19.95 plus $1.00 shipping

        You may not want to rush out and buy one just yet.  Maybe I should test mine and see if it works first.... ?

        Thanks for all your help.


    • Theo

      29/04/2016 7:18:00 PM |

      Added download for Mystic Colour Classic patched System 7.5.

      • Jack Honeycutt

        30/04/2016 10:11:23 PM |

        Thanks so much!  I saw your post last night. I will be using my G4 laptop to down load this patch today.  Then I can move it over to the Color Classic.

        • Theo

          1/05/2016 7:43:12 AM |

          I found most of those items on ebay when I was looking for my ram.  Unfortunately because I'm in Australia they charge $19 for postage.  Too much.  So I found some 64mb chips for a reasonable amount including postage.  I'm happy with 64mb.

          To answer your previous question about the 640x480 mod, at this stage I don't plan on doing it.  I don't really like the idea of modifying the power board.  I've found plenty of games that with run with the native resolution.  I've been meaning to add links to those to this page.

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