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← Telex Tools Repair kit 1 →
Paper-tape puncture 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.
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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.
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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.
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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.
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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).
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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
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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.
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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.
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English: punched paper tape key.
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© Crypto Museum. Created: Monday 12 February 2018. Last changed: Thursday, 03 January 2019 - 08:30 CET.
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