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DISASSEMBLY / ASSEMBLY
2.1 Disassembly
2.1.1 Case
1. Remove all cables from the bottom and rear of
the Computer. Position the Computer on its rear
panel to provide easy access to the case bottom.
Remove the ten screws from the case bottom.
Notice the different types and lengths of screws
and note their positions. Set them aside in
groups.
2. Position the Computer upright and remove the #6
screw and washer from the top of the back panel
of the case.
3. Very carefully remove case top, lifting straight up
and setting it aside to the left (if facing video
screen). Be careful not to exceed the length of
the video cable.
4. Remove screws from the chassis shield and the
ground connectors and remove the shield.
2.1.2 CPU Board
1. Remove the six screws which attach the RFI
Rear Shield to the metal CPU mounting bracket.
This bracket is also held in place with tape at the
lower part of the bracket. Carefully peel the tape
away from the shield so that it may be reused.
2. Remove all cables connecting the CPU Board
(power supply cable, video, keyboard, and
cassette cables, and if applicable, the RS-232,
sound board, and FDC interconnect cables).
3. Remove the eight screws fastening the CPU PCB
(three at the top and bottom and one on either
side of the board in the middle.
4. Make sure all cables to the CPU Board have
been disconnected then remove the Board. (If
your unit uses plastic spacer mounts to hold the
Board, press the small tabs on the mounts
through the mounting holes in the PCB and
gently pull the CPU Board off.)
2.1.3 FDC Board (optional)
NOTE: The CPU Board must be removed before
removing the FDC Board.
1. Be sure to disconnect all cables to the FDC
Board.
2. Remove the screws holding the FDC Board to
the metal chassis and remove the Board.
**Not applicable to all units.
2.1.4 RS-232 Board (optional)
NOTE: The CPU Board must be removed before
removing the RS-232 Board.
1. Be sure to remove all cables connecting the RS-
232 Board.
2. Remove the screws connecting the PC Board to
the chassis and remove the Board.
2.1.5 Main Power Supplies
Three different power supplies are used on the Model
4 Computer, depending on the initial configuration of
the unit. If the unit is supplied with 16K RAM and
cassette input, Power Supply Assembly #879002 1 is
supplied to provide DC voltages required to power
the computer. It is mounted on the front side of the
main CPU mounting bracket at the rear of the unit. If
disk drive(s) are added to this computer, a second
power supply is mounted to the LH disk drive
mounting bracket.
If the computer is supplied with 64K RAM and a
single or dual disk drive, then power supply
#8790043 or #8790049 is supplied to power the unit.
This power supply is mounted at the left side of the
LH disk drive mounting bracket. It is attached to the
CPU mounting bracket by screws through the heat
sink bracket of the power supply.
1. Remove all interconnecting cables to the
board(s). These include the power supply cable,
video, keyboard, and cassette cable. If
applicable, also remove the RS-232 and FDC
power connectors and the disk ribbon cable.
2. Note the position of the ground tab and remove it.
3. Remove the screws which attach the power
supply to its mounting support (four for the 38W
power supply and two for the 65W power
supplies). Spacers separate the 38W power
supply from its mounting bracket. The 65W
power supply is provided with insulated standoffs
to prevent shorting the power supply against the
metal disk drive shield bracket.
4. Carefully lift the power supply out of the
computer. If the unit is one which has been
upgraded to include a disk drive and is equipped
with two power supplies, it may be necessary to
remove the Main CPU mounting bracket to
provide access to the mounting screws of one of
the power supplies.
2.1.6 Disk Drives (optional)
1. To remove the Disk Drive in the top position,
carefully remove the FDC inter-connect cable
connected to the rear of the Drive. 2.
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