Jamaica 12 ch12 Electronics

               electronics
              -------------
            written by iopop


  last time i promissed to explain how
to make a device switch for the c128d
and how to make a pause switch. as i am
running out of time, the latter will
have to be postponed.

                WARNING!
               ----------

  if you have never done any soldering,
i recommend that you get reliable help
to do the job or to learn to solder.
remember that we are NOT responsible if
anything goes wrong!



         DEVICE SWITCH FOR C128D
        -------------------------

  not beeing able to change the device-
number of the internal drive of the 128d
is a constant source for irritation. if
you wanted to use your 1541 or 1581 as
#8, you couldn't do it. now is the time
for an operation to change this.


  what you have to do is basically the
same even if you have the 128d with the
fan and the plastic casing or if you
have the later model in the metal case.
you have to find the address jumpers
J1 and J2 and connect them to a switch.

  in the older 128d with the plastic
case, the drive is a true 1571 and the
circuit board is separate. it is located
in a metal shield-box behind the drive-
mechanism. you will find J1 and J2 just
besides the U9 chip. there is even the
text DEV NO. the jumpers are two pairs
of squares.

  the 128d in a metal case has all the
electronics on the one single circuit
board and the part beneath the drive-
mechanics, carries the circuits for the
drive. right below the left edge of the
drive and between the U112 and U114
chips, you can find the J1 and J2
jumpers. they are not marked, at least
not on all boards of this model. those
jumpers are shaped like two pairs of
half moons connected to a triangle in
the copper pattern.

  both types of jumpers have a thin lead
connecting each pair. cut this thin lead
and solder a pair of wires to each pair
of jumper halves and connect them to a
switch. if you cut only J1, you can
settle for only one switch, but then you
can select only #8 or #9. cut both and
you can choose between # 8,9,10 and 11.

   the jumpers should look something
like below.


                J1 or J2

     plastic case       metal case

     *****  *****          *  *
     *****  *****        ***  ***
     *****  *****       ****  ****
     ************       **********
     *****  *****       ****  ****
     *****  *****        ***  ***
     *****  *****          *  *

          ^^                ^^


           cut this conection!
       solder a cable on each side
        and connect to a switch.


  if you want to show off or be smart,
you can use a rotating hex-switch. for
swedes, use ELFA 35-364-63. i also
suggest that you add a separate reset-
button for the drive to the front. at
least if you expect to change the device
number while you work. when you flip the
switch for a new device number, you must
also reset the drive.


  hope you understand everything. if you
have any reactions to these small
articles or want to share experiences,
then you are welcome to contact me.

  also if you own a blueprint of a
circuit board to either c64 or c128 then
i'm very interested to buy it or have a
copy of it!

        thanx for your attention!