                          Installation Instruction
                          [For C-128 Video Upgrade]
 
    [1]  Allow ample work area.  Spread out a towel or two to avoid
    scratching C-128 case, and help catch loose screws.
 
    [2] You will be dealing with extremely sensitive IC's.  Please follow
    usual precautions to avoid static charges.
 
    [3]  Turn over computer (with front facing you), Remove six (6) screws,
    1 at each back corner, 1 in the center, and 3 across front. (Older
    models have phillips-head machine screws, here use medium size phillips
    screw driver #1.) Newer models will have hex-shaped insert screws.
    Here use a 5/64 hex key (alan wrench).  Now turn computer right side
    up.
 
    [4] The top and bottom halves of the computer are now held together by
    two interlocking plastic tabs.  The two tabs protruding down from the
    top have "teeth" pointing outward, that interlock with the bottom.
    These tabs are located at a point between the top row of number keys
    and the single row of function keys at both sides of the keyboard.
    Press the top IN at this spot, (away from the base and towards center),
    as you lift the top up. You may also try to pull the base OUT at the
    same point. Once one side is free, the other will follow easily.
 
    [5]  (a) Note orientation of LIP part of pilot light LED plug, attached
    to left side of circuit board, (It points out.)  Pull apart mini plug.
 
         (b)  The keyboard is attached to the circuit board with a
    multi-wire mini plug.  Here too, pull apart plug, and NOTE orientation.
    (There is a brown wire closer to power switch....but check out unit
    being worked on for variation.)  When seperating this plug, note that
    the two plastic parts merge completely together.  The "stilts" coming
    out of the circuit board are NOT what it is pluged into.  They are part
    of the bottom half of the plug.
 
         (c) Remove the heavy braid ground wire which also attaches the
    keyboard to the circuit board with a hex key or phillips head.
 
    [6]  Free the RF shield from the board.  At left rear-center is a large
    phillips head screw.  Remove it.  Counting this screw, the shield is
    attached to the board by 7 hex screws.  Remove all 7.  Holding the
    shield to the base are also twisted tabs, at 4 places along the front,
    and left edge.  GENTLY turn tabs straight with needle-nose pliers.
    WATCH direction tabs are twisted, some go one way, others the other.
    Finally, just above the keyboard mini-plug on the right side by a tab,
    the RF shield is soldered to the board. Unsolder at this point, and
    then RF shield can be removed.
 
    [7] On the main board is a small metal box, at left-center, actually
    the only one there.  The two chips to be replaced are located inside.
    Gently pull up and remove the lid.  The chip locations are marked on
    the circuit board as U23 and U25.
 
    [8]  Seperate the circuit board from the bottom RF shield, by carefully
    twisting the tabs holding it to the board.  Leave the bottom RF shield
    in the bottom plastic case, and lift out the circuit board, with a
    "left pull and up" angle, so that plugs inside plastic base slip out
    before lifting up.
 
    [9]  Remove chips U23 and U25, by either a clip and unsolder or simple
    unsolder method.  The old chip pins may be bent on the bottom, if so
    straighten before pulling out. EXAMINE carefully for damage!!  If any
    see below before proceeding!! Insert IC sockets, bending bottom pins
    for a tight fit, and solder in place.  Plug in the two #4464's noting
    that the "dimple" on the #4464's line up with the "dimple" outline on
    the circuit board.
 
    [10]  Reassemble casing, carefully reversing each step.
 
    Ooooops!!
    There are three common goofs, which should be avoided, but if they
    occur, here are the patches:
 
    [1]  Solder "ran" and now two pin connections are crossed. Okey, this
    is easy, just unsolder the connection, carefully seeing that no other
    pin connections are crossed.
 
    [2]  In unsoldering the old chip, the pin connection got burned out.
    Okey, this is a bit more tricky.  You have to examine the circuit board
    both the top and bottom sides, and trace the connection from the burned
    out pin hole to where it goes.  [If you have a schematic, by all means
    use this.] Then, after inserting the IC socket, use a "magic marker" on
    the bottom of the board to mark the burned out pin, and its connecting
    point. Remember when working on the board bottom, its locations are
    reversed, so double check that you are tracing connections correctly!!
    Take a loop of light weight wire, allow for a loop longer than the
    distance to be connected, and solder the wire to the two points.  Use
    electric tape to isolate the two solder connections from any near by
    pins, at both ends of the wire. Then flatten this wire to the bottom of
    the board, going around the "pin hills". And finally take several long
    pieces of electrical tape, maybe 4 or 5 inches long, and secure the
    wire to the bottom, so that it is flat against the board.
 
    [3] In removing the old chip, part of the circuit board tracing tore.
    Well, this is pretty much like goof #2 above.  Make sure that there is
    no loose tracings to cause a short.  Trace out the connection, go to
    the bottom of the board, and solder in a wire splice connection as
    described in #2.
