Macintosh LC 575 “Mystic” logic board recap, install into Color Classic II chassis

[Mr. Fahrenheit]

I purchased a Macintosh Color Classic II earlier this year and thought the 68030 33mhz would be enough for me. While it was great, I really wanted to try a 575 board in it (to make it a “Mystic”).

The board I bought looked clean and was promised to be working yet when I received it, I would get system bombs on boot. So I set it aside until today, when I was looking for something to do.

I recapped it. Letting it dry now. We’ll see if it works after.

I don’t plan to do the 640x480 alteration to the Color Classic chassis/analog board. I am first trying out the enabler hack to see if it works. If that doesn’t make it work I will be doing the resistor swap on the board to change the resolution.

Any input welcome as I’m new to the Mystic side of tinkering.

 

[KnobsNSwitches]

I run my mystic CC at the original resolution. The ResEdit mod is easy enough to do and it just seems 'right' for the screen to me.
IIRC the instructions are fairly straightforward, but I know I have the gusd file and instructions squirreled away somewhere.

 

[Mr. Fahrenheit]

I run my mystic CC at the original resolution. The ResEdit mod is easy enough to do and it just seems 'right' for the screen to me.
IIRC the instructions are fairly straightforward, but I know I have the gusd file and instructions squirreled away somewhere.

I thought I had a hacked system folder for this but I’m getting a bomb on boot.

Could the hack not have applied or do you think this is a hardware problem?

 

[Drake]

Since my LC575 board is a spare I purchased just for my CC to swap in I did the resistor mod to lock in the resolution for that board. I can still swap in my CCII board if needed and it keeps the chassis ready for testing customer boards as well.
One of my last profile posts is the 575 board with added heatsink, custom vram and one of my battery mods wired up and affixed with velcro

https://tinkerdifferent.com/attachments/20211023_101856-jpg.233/

 

[Drake]

I thought I had a hacked system folder for this but I’m getting a bomb on boot.

Could the hack not have applied or do you think this is a hardware problem?
View attachment 942

that's a software issue right there!

 

[Mr. Fahrenheit]

SUCCESS!!!

 

[Mr. Fahrenheit]

The solution is to remove the 000 resistor at r116. I managed to also remove the pad by accident. Oops.

Then install a 4.7k ohm resistor at r109. I stole a “472” resistor from a dead LC475 board. Apparently you can also use a 000 resistor here but I chose to go with the desired method.

First boot it worked without any ResEdit hacking. Just how I want it.

The Color Classic II Mystic upgrade is complete and a success. I can now boot into any standard OS install without hacking the system file first. Bliss !!

 

[This Does Not Compute]

Does that modification to the board affect its ability to work in a 575 chassis?

(A CC II is on my list of machines to get. Someday!)

 

[JDW]

My video on this LC575 MB swap process will be out within a few days.

The 065 v1.1 enabler is only required for System 7.1. The fiddly ResEdit hack is for System 7.5.5 (no enabler required), but I did not do that because I have other things I need to do in this CC video series.

My CC will be upgraded to 640x480 because it makes zero sense in my mind to have a color Mac at your disposal and deliberately ban yourself from the numerous apps which sadly demand a 640x480 resolution. The Analog Board hardware hack is easy enough to do, so it's really a non-issue for most people have a high resolution and detailed video guide to help. As to keeping the stock screen resolution for sentimental reasons, well, I'm not so strict. I've always put my old Macs to more practical uses; and let's face it, Apple machines in their stock condition aren't always practical. My first Mac was the 128K in 1984 and I didn't have the external 400K drive or a hard disk, so I lived through disk swapping hell. PTSD trigger!

I do have limits regarding vintage Mac upgrades though. I will not, for example, turn this precious CC of mine into a monster PPC machine. I'm a die hard 68k fan. And speaking of "fans," yes, I'll put out a video on that too.

 

[JDW]

Does that modification to the board affect its ability to work in a 575 chassis?

I believe that modding the LC575's MB in that way would indeed cause issues when placed back in the LC575 chassis, but I have not actually done that to verify my assumption.

Honestly, I'd rather not mod my 575 motherboard. I prefer to do the Analog Board mod instead to get 640x480.

 

[Mr. Fahrenheit]

My video on this LC575 MB swap process will be out within a few days.

The 065 v1.1 enabler is only required for System 7.1. The fiddly ResEdit hack is for System 7.5.5 (no enabler required), but I did not do that because I have other things I need to do in this CC video series.

My CC will be upgraded to 640x480 because it makes zero sense in my mind to have a color Mac at your disposal and deliberately ban yourself from the numerous apps which sadly demand a 640x480 resolution. The Analog Board hardware hack is easy enough to do, so it's really a non-issue for most people have a high resolution and detailed video guide to help. As to keeping the stock screen resolution for sentimental reasons, well, I'm not so strict. I've always put my old Macs to more practical uses; and let's face it, Apple machines in their stock condition aren't always practical. My first Mac was the 128K in 1984 and I didn't have the external 400K drive or a hard disk, so I lived through disk swapping hell. PTSD trigger!

I do have limits regarding vintage Mac upgrades though. I will not, for example, turn this precious CC of mine into a monster PPC machine. I'm a die hard 68k fan. And speaking of "fans," yes, I'll put out a video on that too.

Yet, to me, I mostly enjoy experiencing things most as they were. Things don’t like to run on 512x384 in color. That’s fine. I just pull out an overclocked 475, or a Quadra 800 for that. In this box I can put my IIe card and enjoy Apple IIe software at the native resolution.

Yet it’s now fast enough to boot up Mac OS without having to wait forever. I’ll purposely handicap it with 36MB of ram so it doesn’t take 2 minutes to boot.

For me, for the same reason, I don’t go after accelerator cards. If I want a faster Mac I just pull out a faster Mac. When I boot up a IIsi, it’s to relive those horrible days in 1994 that caused me to run it on 16 shades of gray for speed.

As for overclocking, I do it sparingly. I have duplicates so some run overclocked and some don’t.

I can’t wait for your new 575 upgrade video.

Also, JDW, can you please run a Norton Utilities 3.1 “System Info” benchmark on the video speed of your 575 in 256 and thousands of colors and let me know the video bench numbers? I’m trying to compare with my numbers here.

 

[JDW]

The reason I don't whip out an alternative Mac from my closet is I live in Japan and lack the space for the expansive vintage Mac collections of my peers. (Yes, I do get rather envious of you folks at times.) When one has few options for vintage Mac color, one tries to maximize the option he has.

As to RAM on the Mystic, I still have mine at 36MB. That was the RAM limit back in the day, and since I won't be doing Photoshop work on this Mac, there is really no meaning to have more than 36MB on it. And while a video about a 128MB RAM upgrade would be fun, you are correct about the crazy long boot process with too much RAM. I also don't want to pay the crazy prices for larger RAM sticks that I've seen online either (especially with international shipping to me in Japan).

My video includes not only the Norton 3.5.3 System Info benchmark but also MacBench 3.0 and Speedometer 4.0.1 too. I wanted to be thorough. And although there are other benchmarks out there, I have more CC videos planned, at which time they can be introduced too.

I'd like to humbly thank @Kay K.M.Mods for all his amazing Color Classic guidance. He is my CC 先輩 (Senpai)!
本当に有り難うね、Kay!
Kayさんが居ないと困る！

 

[JDW]

...one of my battery mods wired up and affixed with velcro

https://tinkerdifferent.com/attachments/20211023_101856-jpg.233/

@Drake , where are those battery mods sold? And if not sold, do you have a photo of the battery side? I'm curious as to what battery you are using.

You see, the stock battery is 800mAh. I measured current consumption on the LC575 MB (disconnected) with a 4.5V power supply attached and found it to require about 63µA continuously. That's actually a rather large power draw, which explains the 800mAh battery. Kay Koba has used 3 LR44 batteries in his mods, but they are only 120mAh. I myself was thinking about SR44's which are 140mAh, but the price is rather outrageous considering you really do need something closer to the original 800mAh battery.

I have found drop-in replacements for the stock battery sold in the US, but sadly, the price for shipping to Japan exceeds the price of the battery itself, and no one here in Japan sells a 4.5V 800mAh equivalent that I have found.

All said, a triple LR44 replacement battery would last a mere 79 days when disconnected from a wall socket.

• LR44: ( 120E-3 / 63E-6 ) / 24 hours = 79 days
• An SR44 would last 93 days.
• The stock battery would last 529 days

 

[JDW]

I had pondered a AA or AAA solution, but in my experience, those batteries leak worse than an old SMD cap from the 80's! You really need to keep an eye on those. The stock "cube" batteries don't have a leaking issue. A trio of LR44's are much safer, especially the Anti-leak variants (maybe only sold here in Japan?).

The thing the AAA battery solution has going for it is capacity. 1000mAh on an LC575 will give you 661 days of unplugged battery life. That's simply outstanding! But at what point it will leak is anyone's guess.

All said, whatever gives me the longest battery life, that is compact enough to fit inside a CC, that won't leak and harm the MB, and which can be had for a reasonable price (including shipping to Japan), is the solution I am pondering for a video.

 

[Drake]

@Drake , where are those battery mods sold? And if not sold, do you have a photo of the battery side? I'm curious as to what battery you are using.

You see, the stock battery is 800mAh. I measured current consumption on the LC575 MB (disconnected) with a 4.5V power supply attached and found it to require about 63µA continuously. That's actually a rather large power draw, which explains the 800mAh battery. Kay Koba has used 3 LR44 batteries in his mods, but they are only 120mAh. I myself was thinking about SR44's which are 140mAh, but the price is rather outrageous considering you really do need something closer to the original 800mAh battery.

I have found drop-in replacements for the stock battery sold in the US, but sadly, the price for shipping to Japan exceeds the price of the battery itself, and no one here in Japan sells a 4.5V 800mAh equivalent that I have found.

All said, a triple LR44 replacement battery would last a mere 79 days when disconnected from a wall socket.

• LR44: ( 120E-3 / 63E-6 ) / 24 hours = 79 days
• An SR44 would last 93 days.
• The stock battery would last 529 days

I have them listed in the trading section for $1, albeit they are just cr2032 holders meant to slot between 1/2AA holders in compacts, LCs etc.
And from your detailed explainations I can easily see how my efforts to add one to a 575 board may be silly

 

[JDW]

...they are just cr2032 holders meant to slot between 1/2AA holders in compacts, LCs etc.

CR2032's are 225mAh, and therefore would yield 149 days of life on an unplugged LC575 motherboard. Better than LR44 or SR44 batteries, to be sure, but much less life than the stock 800mAh battery.

 

[Drake]

CR2032's are 225mAh, and therefore would yield 149 days of life on an unplugged LC575 motherboard. Better than LR44 or SR44 batteries, to be sure, but much less life than the stock 800mAh battery.

@Stephen also has a design which houses 2xCR2032 and diodes appropriate for such. I can mail you one if you like?

 

[JDW]

@Stephen also has a design which houses 2xCR2032 and diodes appropriate for such. I can mail you one if you like?

When I spoke to him about that PRAM battery in late October, I had the understanding it was a replacement PRAM battery for the 128K~Plus. We spoke about the diodes used in the early design too, and I had mentioned that because there is already a reverse polarity protection diode on the motherboard, so diodes on the replacement PRAM battery solution are not needed. I was not aware he has made other models suitable for newer vintage Macs.

 

[Kay K.M.Mods]

I did some work for @JDW today. You can see it in his video:

 

[Stephen]

I was not aware he has made other models suitable for newer vintage Macs.

Khajiit has wares... or more specifically, I work on many projects! You can find the meowTOAST on github, which also lists the meowTWOast (meowTOAST v2). The board we discussed ended up being a bit too short in the first revision — I'm not really satisfied with the idea until JLC can provide an appropriate battery holder for the PCB.