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macintosh classic works but not everything

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I'm just going to list what I have done and symptoms.


Checkerboard screen

Replaced caps on logic board

cleaned logic board- as best i could

Reflow some joints

Verify 5 and 12 volts  within range


At this point I got rid of the checkerboard screen,


Will not boot from hard drive

Will not boot from floppy

Will boot from on board rom by pressing the 4 keys

Never hear any audio, at any point through any process

When booted from rom it will not see either drive

HD Spins up and sounds normal

Floppy spin a disk for 1 second then nothing.

Will periodically reboot while it's booted into the rom

Remove 1 or both drives from logic board has no effect still will not see either drive.


At a loss where to go from here, I'm leaning toward the power supply.




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  • 68kMLA Supporter
Posted (edited)

Welcome to the forum.


Post good quality photos of your logic board please, we might be able to spot something causing some issues. If it's not squeaky clean, I would retry cleaning the board to get it that way.


Do you know that the hard drive and floppy drive are good? Have you got spares to test with? The hard drives in these are usually dead at this point (spinning up doesn't mean it will work).


Have you recapped the analog board yet? I've never seen a Classic without capacitor leakage on its analog board yet. The cluster of caps next to the speaker tend to be the worst.

Edited by joshc
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So I have recapped the analog board, This fixed the random reboot problem. Seems to function better over all.

Still no HDD or Floppy drive show up on the desktop. Boots fine every time now, but only from the ROM boot.

I'm thinking this is a controller problem on the logic board. What chip is the disk controller?


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  • 68kMLA Supporter

Your logic board doesn't look very clean. Scrub it with Isopropyl Alcohol and a toothbrush. Sometimes I even scrub them with dish soap and water. Either way, I take it straight out to the garage, and blast the board with the air compressor to get every drop of moisture off of it, and then I let it dry for 24 hours.

I have a guide/build log here that might help.

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