Lesson 2/Learning Event 6
(1) Jumper wire is usually of black and white pairs. The wire is tinned
soft copper, solid conductor, designed to wrap and solder easily.
(2) Jumpers are always fed through frame rings with 2 to 3 inches of
slack to avoid breakage caused by personnel moving pairs during work
procedures.
(3) Notice that no jumpers stretch vertically between blocks; they
stretch vertically only through the rings.
This is done to provide space
for the hands of technicians working behind the blocks.
(4) The procedure for wrapping and soldering jumper wire to terminals is
the same for cable, except that jumper wires are never pulled taut.
b. Identification.
An orderly system of numbering blocks and their
terminals on a distributing frame is a necessity. Each technical controller
must be acquainted with the numbering system used, and must know how to
trace circuits by that numbering system.
Further, he must know how to
locate circuits through cross-references in the records. Each station keeps
a local ledger in which each circuit is given a number and informally
described.
In addition, DCA forms are completed for each circuit,
constituting a formal record. Most of these documents cross-reference jack
identification, equipment type and location, circuit number, and wiring.
The ledger must also contain an explanation of each abbreviation used.
There are few items more disconcerting to a controller than unknown and
unexplained abbreviations.
Under conditions of stress they present
insurmountable psychological hazards.
Avoid them in every way possible.
Moreover, the records must reflect accurately each change to a circuit,
regardless of how minor. A technical controller does not have the time to
fathom the mysteries of unrecorded and modified circuits.
c. Cross-Connect Records.
The need for records of cross-connects by
jumpers at the distributing frame is well illustrated by the rear view of
patching bays shown in figure 2-13.
All of these many cable pairs are
interconnected by jumpers at the terminal blocks on a distributing frame out
of view to the right. A sample blank form that may be used for recording
jumper interconnections is shown in figure 2-14.
(1) A space is left at the top of the card for notes.
(2) LOC indicates location of equipment.
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