ByteRot :: Macintosh Classic II Logic Board Removal

BYTEROT - retro PCs, consoles and lost software

Get an account

Accounts are free. Join #retro on irc.fxnet.org, identify with NickServ and type !req.

[ how ]

IRC

#retro on irc.fxnet.org
6697 ssl · 6667 plain
modern + vintage clients welcome

[ vintage how-to ]

Sections

OS 1,075

DRIVERS 61

SOFTWARE 22

GAMES 10

UTILS 37

DOCS 561

INCOMING 0

REQUESTS 0

LIBRARY 25,406 files

Some stats

releases	1,766
last 24h	+750
online	404.1 GB
library	1.2 TB
members	0
updated	2026-10-04 23:40

Macintosh Classic II Logic Board Removal

Device	Macintosh Classic II
Difficulty	Moderate
Time	15 - 20 minutes
Steps	8

This guide is by oldturkey03 on iFixit and is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 3.0. ByteRot mirrors it for non-commercial preservation: formatting changed and photos resized for old browsers; full-size photos and the text are on the FTP in /DOCS/REPAIR. Original guide >>

This guide shows the removal of the Logic board. Straightforward with no hidden or proprietary screws.

Tools: T15 Torx Screwdriver

Step 1

• Here is one of the vintage computers in my possession. It is a Macintosh Classic II M4150. Apple considers this obsolete and " information about these products is no longer updated as of 9/1/98 "
• On powering it up, It originally greeted me with a checkerboard pattern that quickly converted into this pattern. The checkerboard pattern is/was commonly caused by bad Ram memory. Considering the age of this computer, leaking capacitors are a strong possibility. Time to check.
• CAUTION: This computer contains a CRT. That means there are some high voltages involved when working on this. Use proper CRT safety while working on it.
• The cover is held in place by four (4) T-15 screws. Two (2) on the bottom

Step 2

• and two (2) under the top (handle)
• The bottom ones are easy to remove
• The top ones are a bit of a challenge due to the depth of the holes.

Step 3

• There was just not enough room to get a good grip on the driver.
• Luckily this iFixit driver has a hole on the top part. I used a tool to gain some mechanical advantage. While applying downward pressure on the driver, turn the tool to the left to loosen the screw
• Once loosened, the iFixit extension that came with my set, works perfectly to remove the screw,

Step 4

• Here are the four (4) screws. The two bottom screws are M4X15mm The top screws are those typical found in plastic to sheet metal joints.
• With the screws removed the cover will slide off.
• BEst practice is to lay it down and pull the case straight up. It may take some force due to the tight fit and years of storage etc.

Step 5

• Here is what the inside looks like.
• CAUTION: Remember the High Voltage. Do not touch anything with bare hands etc. Right now it's look but don't touch
    • Power supply (Sweep Board)
    • Flyback Transformer
    • Video card
    • CRT
    • SCSI Hard drive
• Hard drive on top with the Floppy drive on the bottom

Step 6

• If your Classic II has the memory expansion board installed, it will be in this slot. It will need to be removed.
• Next is the 50 pin SCSI HDD cable. These cables feel heavier and are more rigid than the IDE cables used in 90's
• Pull the cable straight up. It may require some force, but there are no locks etc. to be removed. Just pull.

Step 7

• Next is the logic board power cable.
• Pressing on the plastic tab will release the lock. Pull the cable up to remove it
• Here is the Floppy drive cable. Red stripe always connects to pin one (1) on the connector

Step 8

• Just pull the cable out of its connector. No locks on this one either.
• Next grasp the logic board by its edge and pull it out of the chassis
• Here is the complete logic board. Battery and RAM modules clearly visible. Luckily no leaky battery. The board has some dust and shows some contamination. Overall it is in good condition for an almost 30 year old piece of electronics.

Conclusion

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

Credit