390 THE BELL SYSTEM TECHNICAL JOURNAL, MARCH 1957 



The carrier channel installation and lineup procedure is set up on the 

 basis of using the test set and a generally available \'olt-ohmmeter to 

 make a series of measurements in a specified order. This will permit 

 potentiometers to be adjusted as necessary until the specified meter 

 readings are obtained at built-in test points. Lineup of the terminals and 

 repeaters done first in the central office to insure proper operation and 

 then at the in-plant locations to check system performance. 



Maintenance will be handled on a complete terminal replacement 

 basis and will consist of making a series of checks with the test set to 

 determine whether the terminal is functioning satisfactorily. If it is not 

 and it cannot be adjusted to restore satisfactory operation, a replace- 

 ment terminal will be used to restore service. All repairs and isolation of 

 trouble within the terminal unit or on the individual boards will be han- 

 dled at a centralized testing or repair point so as to require a minimum 

 of personnel with electronic experience. The test set has been designed 

 to handle all tests for a PI carrier system, when used with the volt-ohm- 

 meter, and when used bj^ trained personnel will permit trouble to be 

 isolated to a given printed wiring board in the Pi carrier equipment. 



9. ACKNOWLEDGMENTS 



The authors wish to thank all their colleagues for their important and 

 necessary contributions to this paper. Particular appreciation should be 

 expressed to E. H. Perkins for his contribution to the first half of the 

 paper and to D. H. Smith for Section 6 on power supplies. 



Fig. 31 — PI carrier 7F test set. 



