On 2010-10-21, Karl Townsend wrote:
I need to make up cables with 50 pin ends, two rows of 25 on .1
spacing. I've never done this. Are the parts below all I need? Any
instruction on putting the IDC end on?
50 conductor cable
http://www.alliedelec.com/search/sea...y&Ntt=608-2905
Interesting -- flat cable bundled up into a round jacket. That
is convenient.
But you may (or may not) want/need to terminate the shield shown
in the details of the cable. It will not normally connect to any pins
in the connector.
IDC socket
http://www.alliedelec.com/search/pro...px?SKU=5182308
O.K. That one has a single bar on the back to force the wires
over the pins, which are typically a two-petaled tulip which penetrates
the insulation on either side of the pin, and then cuts in to make
contact with the wires.
There are usually optional secondary bars to handle the stress
if you unplug and re-plug frequently.
Anyway:
1) Get a few spare connectors.
2) Be careful that the connector is truly at right angles to the
cable. If at an angle, the spacing of the pins won't match the
spacing of the wires, and you will wind up with adjacent wires
shorted by the pins where they punch through.
3) You can squeeze the connector onto the cable using a good vise
with parallel jaws. Some styles need notches in the pusher bar
to clear pins which guide and lock the strain relief (e.g. T&B
Ansley blue-ribbon style (commonly mis-called Centronics style)
connectors.
And ideally, you have a lever which moves the pusher bar down to
a specific height, and the connector body in a guide holding it
at the right height for the pusher bar.
4) Be sure to get the same edge of the cable (either a different
color stripe, or a brown wire (for multiples of ten wires, start
on brown, end on black) lined up with the marked pin-1 end of
the connector (usually a triangle on one side) so the same wire
becomes pin 1 on each side. If that happens, the rest are all
correct.
If you have a lot of these to do -- mill a slot in a block of
aluminum just the right width to hold the connector upright -- and with
a second milled slot just wide enough to accept the keying bump in the
center of the connector. Make the depth of the slot just right (and the
thickness of the aluminum block too) so the dimension from the bottom of
the block to the top of a fully crimped connector is 1.000", and set up
something like a small arbor press with a cross bar to close down to
1.000" height. (Perhaps have the bar longer than the connector-support
block, with 1.000" high blocks on either side to stop the stroke of the
pusher bar.
If you are making it only for a single width of connector (e.g.
your 50 pin ones), mill an extra thickness to at least one side of the
ribbon to hold it lined up while you crimp. Otherwise, make and
adjustable bar for the guide function.
And -- it would be helpful to have another bar for the press,
which carries a steel blade to cut across the full width of the ribbon
cable in one cut. This makes it easier to get things started into the
connector and lined up square. I've actually got two presses from
hamfests. One (the cheaper one) I keep set up with the blade only. The
other (a T&B Ansley press) I have a full set of pusher bars (notched and
not as needed) and a full set of blocks to support the connectors at the
right height. The Blue-ribbon style, and the DB-25, DD-50, DE-9 DA-15,
require the notched pusher bar. And -- the connector goes fully through
the support (which is a U-shaped slot milled in it) and rests on the
bottom, so it uses the full 1" height -- plus the clearance in the
notched pusher bar.
The pusher has an adjustment stop, which when set at '0', closes
to 1.000" precisely. At other settings it is a bit higher, corresponding
to the needs of the connector in question.
The reason for the height and support is so the connector is
not crushed by the press. If using a vise -- be very careful to not
over-do it.
Good Luck,
DoN.
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