Macintosh IIsi Teardown



Teardowns provide a look inside a device and should not be used as disassembly instructions.

Member-Contributed Guide

Member-Contributed Guide

An awesome member of our community made this guide. It is not managed by iFixit staff.

This Macintosh IIsi was made in 1990. It was a part of Apples Three Tier strategy of low end macs in 1990. This included the Classic, LC, and the IIsi.

The IIsi is a cut down IIci with a slightly slower processor and a newer motherboard design with built in cache. It has a 250mb hard disk and 8mb of RAM, running System 7.1

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Edit Step 1 Macintosh IIsi Teardown  ¶ 

  • Yes, it only has a floppy drive. Its also 20 years old!

  • Lets begin the repair guide!

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Edit Step 2  ¶ 

  • Pull on the 2 tabs and rotate the top cover towards the front. Remember to remove the one screw.

  • Ports from left to right: Audio in and out, Serial Ports, SCSI, Video, External Floppy, and ADB.

  • I have a nubus Ethernet card installed. Some may have had an expansion card added.

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Edit Step 3  ¶ 

  • It is now open! This Macintosh was designed for manufacturing, which meant it had few or no screws involved with building it. It is all held together by clips and latches. It is extremely easy to work in.

  • There is a 240mb Maxtor Hard Disk and the PDS-Nubus adapter installed. In order to work on the mac, we must remove these first. The Hard disk is an Apple ROM'ed SCSI drive.

  • The top right metal box is the power supply, rated at 100 watts and made by Sony. The bottom box is the Sony Superdrive floppy.

  • Notice the clean, easy to access design. You will never see this again from apple!

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Edit Step 4  ¶ 

  • Remove these two thumbscrews if you have them. Then remove the PDS bracket by pulling straight up.

  • You should now have access to the RAM and PRAM battery.

  • To remove the hard disk, remove the SCSI cable, Power Cable, and pull on the outermost tab on the drive bracket. Lift the drive beyond this tab. Then do the other tab and the drive should come out.

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Edit Step 5  ¶ 

  • To remove the floppy, pull on one clip, and lift the drive. Then release the other and the drive should come free. Remember to disconnect the data cable.

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Edit Step 6  ¶ 

  • To remove the PSU, pull out this clip and pull out on the power supply.

  • Finally, all the components have been removed! This gives you access to clean the motherboard, add RAM or replace the 1/2 Lithium AA PRAM Battery.

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Edit Step 7  ¶ 

  • The motherboard of the IIsi.

  • CPU is a Motorola 68030 at 20mhz. The CPU can easily be clocked at 25 or 30 by replacing the tin clock controllers to the right of the CPU with ones of a higher value. The system can have a FPU via the PDS to Nubus Adapter.

  • System Chipset, designed by apple and made by VLSI. Condensed version of the IIci system logic.

  • Serial Controllers for the LocalTalk ports.

  • Apple Sound Chip (ASC), custom design by apple. It uses the same sound controller as the LC and Classic. These are the first computers with built in sound input!

  • AMD 53C80 SCSI Controller

  • SIWM (Super Integrated Wozniak Machine) controls floppy and power functions.

  • Level 2 Cache. About 4k of it! You have now reached the end. Now please, reassemble your mac and enjoy it!

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Comments Comments are onturn off


Nick, · Reply

Quote from nicksmacandpchelp:


SCSI. It is stated in my analisys of the motherboard. I will add it to step 3 however.

Dr Robotnik, · Reply

How would you swap the drives out keeping the apple ROM

Nick, · Reply

I don't think that is level 2 cache. I think it's the 1mb of on board ram. The only way you could have level 2 cache was on a pds card on the IIsi.

Jonathan Pettibone, · Reply

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