68kMLA Classic Interface

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Color Classic and LC575
Posted by: westcoastech on 2018-10-30 07:45:20
Hi guys

I have a good working Color Classic, recapped board etc. I recently inherited an LC575 but it does not turn on, chimes but no image on screen. The caps on the board have corrosion etc. I know the LC575 can be installed into a CC for an upgrade. Does anyone know if a CC board can be installed safely without any mods into an LC575 machine to test all other components work besides the logic board?

Thanks!

Posted by: rsolberg on 2018-10-30 21:06:32
It sure can.  That's essentially the "Mystic" Colour Classic upgrade/mod.  Before swapping the 575 board in, you can make a small modification to your System file with ResEdit so that it starts up in the right video mode for the CC's analog board/monitor.  This won't affect booting with the stock CC board; it just changes the boot procedure when the 575 board is identified.  See item 2.1.3 on this page for steps: http://www.colourclassicfaq.com/mobo/mystic.shtml

When I did this, I remember booting from a floppy to replace the System file with the modified version, but I can't remember if that's strictly necessary.  If you have a working 575 board and don't do the edit, I think you'll get a chime but no video.

Posted by: Franklinstein on 2018-10-30 21:44:32
Yes it'll work the other way too (CC board into a 575). Unless you have a VRAM upgrade, though, you'll be stuck at 256 or fewer colors.

Basically, logic boards that are physically interchangeable (except for the rear I/O plate):

Color Classic

Color Classic II/Performa 275

LC/Performa 520

LC 550/Performa 550/560

LC 575/Performa 575/7/8

The Mac TV is slightly different, primarily because of the remote receiver that none of the other models had, so I wouldn't try that one.

As noted, while they may physically swap without issue, there may be a software hack required to get the machine to run properly; it seems to apply primarily when moving the 575 board down to a stock CC chassis.

Posted by: westcoastech on 2018-10-30 22:31:59
Great thanks a lot guys. I mostly just wanted to see if the LC575 was in fully working condition besides the logic board, want to see if I have to fix anything else besides the board. Once I fix the LC575 board I am unsure weather I will just use it to get the LC575 up and running as it was originally or use the board as the mystic upgrade in the Color Classic

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