AUTOMATIC TESTING IN TELEPHONE MANUFACTURE 1141 



No. 1 operates. The three capacitors are tested simultaneously by con- 

 necting each of them in series with an 8,000 c.p.s. source and detectors. 

 The detectors consist of bridge type rectifiers and relays. If all of these 

 three relays operate, a series connection through their closed contacts 

 causes another relay to operate and lock up. Finallj^ this relay when 

 operated has open contacts in parallel with open contacts on relaj^ No. 1, 

 so that when the reject cam closes it finds an open circuit and rejection 

 does not occvu*. 



The reader may question the necessity for continuity tests on capaci- 

 tors that have already been tested for capacitance. Perhaps the most 

 convincing answer is that there is an occasional failure on the continuity 

 test. Telephone apparatus is always exposed to more severe conditions 

 in test than it will encounter in ordinary use. The leakage resistance 

 charge and test operations and the transmission tests can on rare oc- 

 casions cause the metallized connections at the ends of the capacitors to 

 open. As the cost of making the final continuity test is vanishingly small, 

 the additional insurance is economical. 



The detail list of checking standards for this machine contains some 

 twenty items. Most of them are modified 425B networks, specially ar- 

 ranged in one way or another to check certain functions of the machine. 

 These are used right in the individual fixtures. 



It is interesting to reflect on the labor saving virtues of this machine. 

 The operator in one eight hour shift handles over five tons of networks. 

 She does it easily and without fatigue. The testing would not be even 

 attempted on a manual basis, because over and above multiple handlings, 

 the added human effort of closing fixtures, operating switches and the 

 like could not be tolerated. 



In contrast to the multiposition set described above, it is instructive 

 to consider two single position sets of diverse character. They are a relay 

 coil test set and a film scale calibrating set. 



THE RELAY COIL TEST SET AT KEARNY^ 



Coil assemblies for the U, Y and UA types of relays^^ are tested for dc 

 resistance, direction of winding and breakdown before assembly into 

 complete relays. INIany thousands of the relays are used in any crossbar 

 office. Minimum and maximum tolerance limits arc placed on their wind- 

 ing resistances, to control cinnulative current requirements and to insure 

 a proper margin of relay operation. Each coil assembly, as presented to 

 the test position, consists of a magnetic core, a solenoidal winding assem- 

 bly and a terminal assembly. A winding assembly may have one, two or 



