Disassembling Macintosh IIsi Power Supply

Written By: Chris Green

Comments: 6

Disassembling Macintosh IIsi Power Supply

Difficulty

Moderate

Steps

Time Required

15 - 30 minutes

Introduction

The Macintosh IIsi Uses a 120/240V AC Power Supply. It provides power directly to the logic board. From there, it is distributed to the rest of the computer.

Tools

Phillips #0 Screwdriver

Step 1

Start by turning the computer around, and remove this #0 Phillips Screw.
There may or may not be a Phillips #0 screw here, depending on whether or not the computer has ever been serviced.

Step 2

Now lift these two clips, and slowly pivot the case up.
You can now seperate the top of the computer from the rest of the machine.

Step 3

The "SuperDrive" is mounted similarly to the hard drive, and positioned right next to it.
Push these two tabs out, and lift the drive up.

Step 4

Flip the drive so it is on top of the power supply, and remove the "Red-Ribbon" cable.
1.44MB floppy drives need a ribbon cable with a red stripe on one side. 400KB floppy drives use a ribbon cable with a yellow stripe on one side. 800KB floppy drives can use a red, or yellow striped cable.
This drive was manufactured by Sony in 1990.

Excellent pictures and easy guide! Thank you very much. My IISI floppy drive started flawlessly after 25y and the disk could be read. however it did it just once. Then I could not eject it any more. It did not work anymore. Can I replace it with a Sony MPF 920E? What type of cableadapter do I need

Georgu Jörg -

Generally these old Macs only work with Apple style floppy drives, they use both a different cable and signaling standard than PC drives. If your drive isn't ejecting your best bet is to either replace it with a similar 1.44MB "SuperDrive", or service the drive. There are some good videos floating around the web about how to repair and maintain these old drives, and it isn't actually too hard to disassemble and clean them.

Chris Green -

Step 5

The fan recieves power from two contacts on the logic board and has no connector.

Step 6

In all of the years that I have worked on this machine, I have found no good way to remove the fan.
The best way to start, is to push in here on the side of the fan.
Being careful not to exert too much force, try to push in, and wiggle the fan outward as such. (2nd Photo)
You can now lift the fan all the way out, and remove it.
The Fan Power Contacts on the Logic Board:

There is no need to pull out the fan. Just take a knife and you can squeeze the tab in step 7

Willy Kaiser - 21/10/16

I wanted to second what Willy said; as far as I can tell one is intended to remove the PSU before the fan. You just jam something the right width in between so the PSU tab is depressed, pull it out, and after the PSU is out removing the fan is easy.

Caleb Hansberry - 24/11/18

Step 7

To remove the power supply, squeeze these two tabs and lift the front up.
On the back of the power supply, there is a tab that also must be pressed to remove the power supply fully. You can then lift it out all the way. A firm tug may be necessary to seperate the power connector.

Step 8

Information on the power supply:
It was made by Sony in 1990, and uses a 10-Pin power connector.

The power supply on mine is corroded. Cannot even do a re-cap. Any suggestions for an alternate power supply or where to buy a reasonably cost-effective replacement?

Charles -

Conclusion

To reassemble your device, follow these instructions in reverse order.

Author

Chris Green

Member since: 11/10/09

36876 Reputation

One comment

I was looking for the schematic for the power supply APS-06 pictured here. The information above would be a little helpful if one was really unaware of anything electromechanical,… otherwise, it’s all pretty obvious I think.

nikitesla - 05/09/18