The main terminations are Jacks on the rear of the machine and groups of 26 single pins that individually plug into 52-way binder posts or plugboards from the Punch Card range of machines.

Above is the type of 26 way Jack which is soldered to the ends of the Letchworth Enigma, Diagonal Board and ‘Commoning’ Jacks. In total 228 Jacks are fitted to the rear of the machine.

More details of jacks

Before the jacks were mounted in the Jack Frame ‘Columns’ it is necessary to fit insulation strips as above. The drilling jig is also shown.

To the other end were soldered individual pins. We have had made on modern CNC equipment something of the order of 6000 in total. Above are examples of these pins together with a test jig designed to ensure that the very slight taper is kept within specification. These were all soldered to cableforms or linking wires.

Cableform production

These pins plug into plugboards or binder post boards. Below are the binder post bases.

At the top and bottom of each Letchworth Enigma is a 52-way connector panel or termination binder post as BTM called it. Above is an image of some of these together with the drilling jig which has been specially produced. Special screws with flats cut in their heads are inserted from the slot end. Special round nuts are screwed on the other side under which are terminated the tags attached to the wires going to the back of the commutators. These special nuts have a taper on the inside into which the brass tapered pins shown above are inserted.

Letchworth Enigma – Electrical

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