[ Some version of all this should be edited together and placed on
Ralph's Mac2400 site I reckon. If there aren't already good
explanations out there for all this, please forward your
corrections/suggestions/editings to this rambling piece, and I'll
pass it on to Ralph. Photos anyone? Ralph, would you have any use for
a piece on the repair? ]
--------------
Gregory,
Regarding the power supply repair, I have done two of these.
There was a rather good description just a few weeks ago, that I am
sure someone will post again.
In case no one does, here's a once over. (Ending up being quite long, sorry)
Depending on how close the frayed part of the wire is to the box and
reinforced part of the wire, there are two ways to go about a repair.
Repair the frayed part of the wire, or cut off the frayed bit and
resolder. (The most common cable failure occurs right next to the
conical rubber reinforcement. This description assumes that is your
case.)
The second method is more involved (cracking open box, tinkering with
the wire, and soldering) but makes for a better and tidier fix. The
first avoids both breaking open the box and the soldering. Both still
working for me.
Assuming you go for 'cut and solder', I'd say that the two hardest
elements of the repair, are in fact the cracking open of the box
itself, and elegantly extracting the inner core of the wire from
within the weave surrounding it.
Tools? At a minimum, you'll need a knife, a THIN tipped soldering
iron, some solder, and electrical tape.
THE CONSTRUCTION:
The cable itself consists of (from out to in) the black insulation,
then a woven 'tube' that surrounds a similarly protected (white)
inner wire. (It is in fact the fraying of this woven part that has
the whole thing failing, with flikering screen etc etc.)
===============
xxxxxxxxxxxxxxx
===============
--------------- central conductor
=============== white insulation
xxxxxxxxxxxxxxx silvery weave
=============== black insulation
The wire (both outer weave and inner wire) then seperate within the
case and are soldered to two holes on the board.
The black reinforcement of the wire at the case is moulded as part of
the wire itself, but simply sits in an internal groove of the casing,
from which it seperates easily. On the other hand, to reuse the
rubber reinforcement, you will need to cut/split it either completely
in two (LENGTH WAYS) or, a better solution, merely cut half way
through to be able to remove the present wire it contains and replace
it with the good part.
As far as the two halves of the case are concerned, they seem factory
sealed. I gently ran a blade round and round the groove between the
two halves until it began to seperate and then carefully cut away at
the rest. Long and slow, but causes the least damage to the casing.
Up to now I have resealed the case by merely wrapping it in
electrical tape until I'm sure my repair has held. Later I'll
probably glue it closed.
Inside the case is a block of electronics that pretty much fills the
interior with what I remember to be a metallic shield (heat
dispersion?) surrounding most sides. This just pops out of the
plastic covers.
THE REPAIR:
(Again assuming the 'cut and solder' option.)
** Please wait to read other postings first. I'm sure someone will
offer photos and a better description. **
** You have an hour ahead of you right? **
** Usual thing, I take no responsability for anything that goes
wrong. But it worked for me. **
Snip the wire close to the feeble-feeling (broken) bit, preserving as
much of the length as possible. Cut on the side away from the case,
leaving the damaged part attached to the case.
Split/cut open the case. Take your time, as the guts are packed in
tightly and sit very close to the casing.
Warm up your soldering iron.
Pop out the innards with cable and conical rubber reinforcement still attached.
NOTE VERY CAREFULLY WHICH PART OF THE CABLE IS CONNECTED TO WHICH
HOLE IN THE CIRCUIT BOARD! Write it down or take a picture.
Using the soldering iron, disconnect both parts of the cable from the
board. The less time this takes the better. Heat is not appreciated
by the electronics.
Switch off the soldering iron for a while.
Now split the conical reinforcement on the cable (see above) and
remove the bits of wire from inside. Trim off the remains of the
cable from either end of it, too. This is also a good time to
understand how the cable is constructed before you attack the healthy
length.
Prepare the cable (this is just one of several probable ways of doing
this). Carefully split/cut open a little over an inch of the black
insulation of the wire. Seperate it from the core and cut it off (the
insulation part). Where you cut off the insulation, gently ease the
internal white wire through and out of the side of the weave. (Like
pushing you arm through the hole in the elbow of your sweater -
sleeve to one side, arm to the other) If I've explained myself
correctly, you should now have a "Y" shape - a black cable ending
with to one side the naked silvery weave and to the other the central
white coated wire. Finally strip a quarter inch of insulation off the
end of the white wire.
xxxxxxx
x xxxxxxx silvery weave
============== x x
xxxxxxxxxxxxxxxxx x
========================= white insulation
--------------------------- central conductor
=========================
xxxxxxxxxxxxxx silvery weave
============== black insulation
<- 1 inch ->
You should now have two halves of the case, the electronic block from
inside, the split reinforcement, and the good length of wire with the
two connectors within seperated in a "Y" ready to resolder.
Time to put it all back together again. Heat up the iron again.
While it's getting warm check your notes as to which connector goes
into which of the two holes.
My own advice here is attempt to soften any remaining solder and
shove the weave part as far as possible into its hole. This way you
dont need any insulation on protuding parts - there won't be any. And
it takes up less room, it gets pretty tight in this space when you
close everything up again.
Simply solder in the other wire into the other hole.
Closing everything up I will leave to personal prefference. What you
need to do is obvious, but how prettily you go about it is up to you.
Myself, I just have held everything shut using black electricians
tape. At least so long as it all tests out OK over a few weeks.
The conical reinforcement I held closed with three turns of wire
round it (fits well into the grooves).
One thing I would advise is using either tape or heat shrink tubing
to further reinforce the cable above the conical reinforcement. A few
turns of electrical tape on past the end of the cone. Continuing the
wire wrap off the cone would be another idea, covering it all in
tape. Had I thought of it at the time I would have purchased some
shrink wrap tubing and used that.
I hope this helps.
Marc
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