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Repair kit
Paper-tape repair kit

Although punched paper tape was once a popular and reliable data storage medium, it was also vulnerable, as the paper could easily get damaged. It could be torn accidentally, or it could be worn out, especially if it was played back several times. In such cases the tape had to be repaired.

The image on the right shows a popular desktop repair kit, that was commonly used for repairing broken paper tapes. It has a metal base and is covered by blue plastic. At the centre is a hinged lever with a spring-loaded knife, and two hinged arms that are used to keep the tape in place.

At the right is a separate arm that can be locked into 8 active positions, or in a neutral position. It is used to punch new holes in a repaired tape, or to delete a character by punching all holes in a row. At the rear left is a recessed area with a cubical box with pre-perforated self-adhesives.
  
Paper tape repair kit - open

For repair, the large hinged arm at the centre is raised, along with the two smaller support arms. The tape is the placed on the base plate – running from left to right – just behind the narrow rig, about 1/3rd from the front edge. It is held in place by small alignment pins that fit the sproket holes in the tape. The short arms are pushed down to keep the tape down when working on it.

If a part is missing, a new piece is now placed in parallel with the old one, and the large hinged arm is lowered. Next, the square knife button at the centre of the large arm is pressed, resulting in a straight clean cut between the two pieces.

The large arm is now raised and a piece of pre-perforated self-adhesive repair tape is placed over the two pieces. Next, the large arm is firmly pressed down (without activating the knife) to ensure that the self-adhesive is properly affixed. It might be a good idea to reinforce the repaired tape by placing an extra patch at the back side.
  
Paper tape repair kit - closed

If a new piece of tape is inserted into a damaged one, it may be necessary to restore any missing characters by re-punching the missing holes into the tape. This can be done accurately with the punch arm at the far right. It is usually placed out of the way, in the rearmost storage position (S).

The punch arm can be brought forward when required. The index to its right shows that it can be locked into any of 8 active positions (1-8): three above the sprocket hole and five below it.

The eight positions are sometimes referred to as channels, levels or bits. Whilst made for 8-level paper tape, the tool is suitable for any format down to the well-known 5-level teleprinter tape. Note that the position for the sprocket hole, or feed (F), is missing. Although it can be punched, it is not recommended as it requires a smaller hole. It is preferred to use pre-perforated tape. 1
  
Operating the puncher

In the image above, the arm is placed in position 7. Place the tape with the selected character position under the arm and push the arm down to punch the hole. Repeat this for any further holes until the character is complete. Several tools were available for finding the required pattern for a given character, like the Baudot definition card, or the Siemens Lochstreifenschlüssel. 2

If none of these tools is available, you may also use our standard definitions. For 5-level tape, use our ITA-2 (CCITT-2) or Baudot or Murray table. For 8-level tape, check out our ASCII table.

  1. A piece of pre-perforated paper tape, with just the feed hole, can easily be made with a teleprinter, by generating NULL characters on a blank tape.
  2. English: punched paper tape key.

Paper tape repair kit - closed Half-way open Paper tape repair kit - open Plastic box with perforated self-adhesive tapes Knife Operating the knife Puncher Operating the puncher
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Paper tape repair kit - closed
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Paper tape repair kit - open
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Plastic box with perforated self-adhesive tapes
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Knife
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Operating the knife
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Puncher
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Operating the puncher

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Crypto Museum. Created: Monday 12 February 2018. Last changed: Wednesday, 14 February 2018 - 11:18 CET.
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