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BELL SYSTEM TECHNICAL JOURNAL 



Fig. 13 illustrates both the open-wire and the proposed cable 

 methods of grouping the jacks. In the arrangement for open-wire 

 circuits the jacks associated with both the lines and equipment are 

 located adjacent to each other in the same test board panel. In 

 cable installations the jacks having similar functions are to be grouped 



Fig. 13 — Typical Jack Assembly Arrangements at Test Board 



together, the groups having different functions being mounted in 

 different panels which may be located in different test board posi- 

 tions. These various groups, in the latter case, are planned as follows: 



1. Primary line testing position for testing and "patching" toll 

 lines only. This position to be used for locating faults in the 

 cable circuits and equipped with a Wheatstone bridge and volt- 

 meter, to permit the necessary electrical measurements for this 

 purpose. This position is also to be used for making temporary 

 changes in the assignments between the lines, and the equipment 

 as a whole, but is not to be arranged to permit changes in in- 

 dividual equipment units, such as composite sets, phantom 

 sets, etc. The jacks to be located at this board are to include 

 those designated as "line jacks" and "equipment jacks," in 

 Fig. 12. 



2. Secondary terminating line positions for testing and "patching" 

 the lines between the "drop" side of the equipment and the toll 

 switchboard circuit. This position is to be used for determining 

 the general nature of a trouble and its general location, i.e., 

 whether it is in the direction of the line or in the direction of the 

 "drop," and for clearing troubles not requiring line tests. This 

 position is not to be equipped with Wheatstone bridge testing 



