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Socketbox (generic)



  You might have thought that there isn't actually an awful lot to say about a socket box. Well...



  It contains two DIN sockets, and two sets of three IDC sockets similar to those found inside telephone extension sockets.

How to wire an Acorn socket box (correctly):

  1. Carefully strip about 60mm (approx. two and a half inches) of the insulator and shielding from the cable. Do not cut the cable.
    Do not strip off any insulation from the individual wires.
  2. Remove the lid from the socket box and identify the positions marked "D+", "D-", "C+", "C-", and "E" (or Ground or Earth).
  3. Fasten the cable to the board using the cable grips at each side of the circuit.
  4. Lay the colour coded wires loosly over the correct places in the IDC blocks:
      Earth     copper or bare metal
      Data +    White with orange trace
      Data -    Orange
      Clock -   Blue
      Clock +   White with blue trace
    If your cable does not comply with this coding, you must make sure you use one twisted pair for clock, and one twisted pair for data.
  5. Put a kink in each wire to prevent it breaking when you insert it into the IDCs.
  6. Ensure the earth wire cannot short against anything in the socket box. A short circuit could damage Econet interfaces or the clock.
  7. Push each wire into place using the cable insertion tool. The tool only fits one way around so don't try to force it.
    If you don't have a tool, you can make do with a large straight-head screwdriver as long as it is about 1mm fat at the end. Anything less might cut the wire, anything more might damage the IDC. Be very careful not to break the wire...
    (this stage is sometimes called "tonking")
  8. Reassemble the socket box.
Wiring SJ socket boxes is pretty much the same procedure...

You may have gathered by the subtle hints that you are not supposed to cut the cable when wiring socket boxes.
This is because you may suffer reflections from each cut end along the cable. It probably won't be noticable on a two or three station network in an exclosed area, but things are rather different on large networks with many machines. Even though the cut-cable socket boxes may be electrically sound, the reflections will impose a severe hit on the network performance.

If anybody suggests you go ahead and cut the cables willy-nilly, they are speaking out of a part of their body that shalln't be mentioned here and obviously have no concern for the operation of the network once it is installed.

Just remember these benefits if you are trying to pull a hundred metres of cable through a wall.

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Copyright © 1999 Richard Murray