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The slow starting LC575 mystery

djorud

Active member
Recently, a fellow vintage Mac fan was kind enough to recap the logic board in my LC575 along with a couple of Color Classics. One thing he observed was the prolonged time for the display to turn on and boot up. It eventually turned on, but only after a long wait. After its return home, I observed the same thing, the period of time being 55 seconds from the time the “on” button on the keyboard was depressed until the display came to life with a Mac face appearing. From there, another minute before the desktop was fully booted and in place. Why was this taking so long? The solution came a couple of days later when I discovered another LC575 logic board stashed away when sorting through some old software. Recognizing what it was, I pulled the newly recapped logic board out of the LC575, put it’s battery on the newly discovered logic board from storage and put it into the computer. Depress the startup button on the keyboard and the startup chime bonged just fine.…but the display remained black. Fifteen seconds later, I hear the ascending/descending loud chimes signaling a problem. So, pull out the board to see if there is loose RAM. RAM wasn’t loose, but I decided to remove the 72 pin module and plug the board back into the computer. This time, startup was within a few seconds. No black screen and no chimes. Okay, pull the board back out and put the 128k simm back in. Once again, 15 seconds of nothing before the chimes sounded off. Pull the board, remove the simm module, replace the board and it starts up right away, booting within 15 seconds. Hmmmm. Now I’m thinking maybe the newly recapped board with 128K of RAM has a similar issue. To check that possibility, I pull the 128K off the board and put the board back into the LC575 just relying on the basic 4K RAM in place. Bingo! Startup bong immediately, 5 seconds later I see the smiling Mac, and a few seconds after that, the desktop is fully booted and ready to go. Lesson learned: When the simm slot has a huge RAM simm in it, the boot time is slowed to a crawl, up to a couple of minutes before it is fully booted and ready to go. I’ve backed down to a 32k simm, and now we’re doing just fine again.

Oh, may as well mention the Color Classics too. They were also recapped when the LC575 was getting the same treatment. I have had the CCs since the mid 90s, but had switched the logic boards to LC550 versions, then added Sonnet Presto 040 accelerators, allowing the RAM to expand up to 36K. I had forgotten how snappy those little guys were! Both are running OS 7.5.5, but are capable of running OS 8.1. Since that’s available only on CD, will have to rummage around here awhile longer until I can unearth an external CD-ROM drive and install 8.1. Never upgraded it years back, but maybe now is the time!
 

Byrd

Well-known member
Yes, the extended boot delay from cold is due to the MacOS built-in memory test. On later (PPC) Macs, this test can be disabled (holding down option + command then double click the Memory control panel); on warm reboots it does not go through with the best.

Glad your LC575 is up and running again, that Trinitron, that sound ... it's a really classy Mac IMO.
 
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