Lay the computer on it's side. Press the two latches on the back and lift the cover up and off. Next you need to remove the carrier that holds the hard drive, floppy drive and optional tape drive. Disconnect the floppy cable and SCSI cable from the logic board. Disconnect the power cable from the power supply. Remove the two screws that hold the drive carrier in place. Slide the carrier toward the back of the computer and lift it out. Next, you need to remove the speaker. Disconnect the cable that goes from the speaker to the logic board. Release the latches on the inside of the front bezel where the speaker is and remove the speaker and the panel in front of it. Now you have to remove the power supply. Disconnect the power supply cable from the logic board and remove the screws that hold it in. Remove the blank bezel by releasing the latches. Lift the power supply out. Remove the expansion cords. Now the logic board is ready for removal. Remove the reset and interrupt buttons. Disconnect the key cable from the logic board. Press the latch near the RAM slots and slide the motherboard toward the front. Lift the logic board out of the computer front first.
First you need to remove the floppy drive. Disconnect the SCSI and power cables from the hard drive. Remove the screw that mounts it to the drive bracket and lift it out.
Remove the floppy drive. Next, remove the screw that holds the CD-ROM to the drive carrier and remove it and it's bracket.
Remove the drive carrier as described in the logic board section. Disconnect the floppy cable from the floppy drive and remove the screw that holds it onto the drive carrier. Lift the floppy drive off of the carrier.
Information provided by Doug Brown.