Computer Mac Classic 1990 (Macintosh)

Computer Macintosh Classic (Mac)

Back in the old days, we had one of these Macintosh Computers in class room. I have one. But it failed to boot showing a broken Mac icon after booting after a few minutes of usage. So I though to give it a try repairing it! And it worked. See me playing some games like TETRIS at the end.

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The back case reads:

Macintosh Classic
Apple Computer, Inc.
Cupertino, California
Assembled in Ireland
Model Number: M0420


Interfaces / Ports

Keyboard / Mouse (5 Pin)
External Floppydisk
External Harddrive
Printer (8 Pin)
Modem (8 Pin)
Loudspeaker (3,5 mm Klinke)

  • Reset Button
  • Reload Button (re - login, soft reset or something, who knows...)

The main board

The main board PCB reads:

APPLE COMPUTER INC. 820-0390-A (C) 1990
.RU T-M 15-V-0  11 N



RAM Connection Pin Re-soldering

Yes, I'm wearing the ESD Wrist Strap connected to main-earth. I also used kapton tape to protect other parts.

After repaired the RAM memory (reflow), it seems to work fine.


Photo Impressions

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This is it, the RAM with extension.

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It reads, APPLE COMPUTER INC. (C) 1990.

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Memory RAM extension slot showing on the right side.

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This is where the RAM memory plugs in.

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Contact pins on the RAM - some are bad, oxidized or even "eaten" away, blank cooper showing below.

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This should made good contact again.

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SIMM installed or not? You have to setup it manually with a jumper switch:

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It was easier to open the screws hidden in the top handle just with a simple small flat head screw-driver.

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