advice needed for my 575 (Mystic) upgrade

2 replies [Last post]
Joined: May 9 2015
Posts: 62

Hi folks....

After my CC logic card became ruined with a broken battery and battery goo ran all over about 1/4 of my logic board, I have decided to do the Mystic upgrade. I have bought a 575 logic board and it is suppose to arrive soon.

I have read this FAQ here:

Before I break anything, I want to make sure I understand something....

Do I understand it correctly in believing that I need to convert my CC to 640 X 480 before I can slide the 575 logic board in?

And if so, once the CC has been converted to 640 X 480 is that all I need to do before I slide the 575 logic board in and boot my CC?

Is this the proper hardware mod to convert the CC to 640 X 480?

"Remove R116 (zero ohms, located on the bottom of the 575 logic board to the left of RP9) and solder a 4.7K ohm resistor at R109 (near R116). If you don't have the proper resistor, you can get away with using the zero-ohm resistor you just removed. Make sure nothing is installed across R110 (remove anything you find there) and you should be ready to go."

If so, how many volts should the 4.7 ohm resistor be rated for?

What are the advantages and dis advantages of doing the hardware 640 X 480 mod vs the ResEdit hack? Do I place a lot of stress on my hardware if I do the hardware 640 X 480 mod over the ResEdit hack? I can solder with the best of them, so I can do the hardware or ResEdit hack. I am just not sure which to choose.

Thanks everyone for the many tips.

jack the new kid

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.
Dr. Webster's picture
Joined: Dec 19 2003
Posts: 1688
Re: advice needed for my 575 (Mystic) upgrade

This page explains the options for screen resolution vs. OS version vs. mod method pretty well:

As for resistor voltage rating, I can't imagine that it needs to be rated for much...maybe 12V at the most. It's all low-voltage DC on the logic board (unlike the analog board).


Applefritter Admin

Joined: May 9 2015
Posts: 62
Re: advice needed for my 575 (Mystic) upgrade

Thank you Dr. Webster. Great link. I will head to it now.

It seems at first blush that an even better 640 X 480 hardware mod is available that will put less stress on the hardware. I will read up on that one and see how it works.

Thanks again.

Jack the new kid