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Ribbon Cable Connections
The main board and socket board are connected together with three identical 16-way ribbon cables.
These cables are terminated in sockets that are called insulation displacement connectors (IDC).
They are called this because they make connection with the cable by piercing the plastic insulation
that surrounds the wire inside the cable. The piercing action is created by pushing the connector's
top section down onto the cable and forcing the spikes in the lower section through the cable. There
is no soldering involved in making the cable assembly and the connection made is both reliable and
strong.
Special tools are available for neatly squeezing the two sections of the connector together.
However, for a 16-way cable it can easily be done in a bench vice. Some connectors have additional
strain relief bars that clamp the cable onto the top of the connector, however, these are not needed
for such a short length of cable and can actually make construction of the assembly more difficult.
If your connectors have come with such a clamp you can simply not fit it.
The red line on the cable lines up with pin 1 on the connector. Pin 1 is usually depicted by a little
triangle shape on the connector near where the cable will be eventually seated. Note that both
connectors are mounted onto the cable so that they face the same way. That is, pin 1 of each
connector is on the same side.
Each connector has two rows of eight contacts. The gap between each individual contact is 0.1” or
2.54mm. This means that the ribbon cable's conductors are spaced apart by 0.05” or 1.27mm.
All three cable assemblies are to be made the same total length of 48mm.
If you haven't made such cables before I strongly advise you to buy some extra sockets and cable so
you can practice first. Once the cable is squashed onto the connector it is not easy to get them apart
again without damaging the connector. Also, the part of the cable that has been pierced cannot be
used again.
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