Manual / Guide · 1950
Describes AE-supplied SxS test equipment: current-flow test set, stepping-switch test set (varying machine), test handset with switch test plug, test stand with 24-terminal jack, and the routine test procedures.
D E P A R T M E N T OF THE ARMY TECHNICAL MANUAL TOOLS TESTING EQUIPMENT AND COMMON SUPPLIES STEP- BY- STEP DIAL CENTRAL OFFICE EQUIPMENT IT- DEPARTMENT OF THE ARMY - MAY 1950 D E P A R T M E N T O F T H E ARLWY T E C H N I C A L M A N U A L TOOLS TESTING EQUIPMENT AND COMMON SUPPLIES STEP - BY- STEP DIAL CENTRAL OFFICE EQUIPMENT DEPARTMENT OF THE ARMY Uliited States Gowernrnent Printing Ofice Washington: 1950 DEPARTMENT OF T H E ARMY WASHINGTON 25, D. C., 10 M a y 1950 TM 11-2111 is published for the information and guidance of all concerned. [AG 300.7 (29 Nov 49)] BY ORDER OF THE SECRETARY O F THE ARMY: J. LAWTON COLLINS Clzief of Staff, United S t a t e s A r h y EDWARD F. WITSEIJL Major General, U S A The A d j u t a f z t General DISTRIBUTION : Tech sv (2) except 11 (50) ; Arm & Sv Bd (1) ; A F F Bd (ea Sv Test Scc) (1); A F F (5) ; OS Maj Comd (5) ; Base Comd (3) ; MDW (5) ; A (5) ; CHQ (2) ; F C ( 2 ) ; Sch (2) except 11 (10) ; Gen Dep (2) ; Dep 11 (5) ; Tng Ctr (2) ; P E ( l o ) , OSD (2) ; Lab 11 (2) ; 4th & 5th Ech Maint Shops 11 (2) ; Two ( 2 ) copies to each of the following T/O&E7s: 11-47 ; 11-107 ; 11-127 ; 11-500 GA,GB,GC, GD,GE,GH ; 11-587 ; 11-592 ; 11-597 ; SPECIAL DISTRIBUTION. For explanation of distribution formula, see SR 310-90-1. CONTENTS Paragraph . Page . Section I General Scope ...................................................................................................................................................... Forms and records ....................................................................................................... ...................... References ............................................................................................................................................ . . I 1 Description and Data of Test Equipment General .................................................................................................................................................. Type 1 test desk .................................................................................................................................. Test sets supplied by the manufacturer ......................................................................................... Other test equipment supplied by the manufacturer .................................................................... Signal Corps standard test equipment ....................................... ; ..................................................... Dial speed and pulse ratio test set .................................................................................................... Type 31 portable dial speed test set .................................................................................................. Buzzer test set ...................................................................................................................................... Test stand .............................................................................................................................................. . . CHAPTER 2 OPERATING INSTRUCTIONS AND THEORY OF OPERATION FOR TEST EQUIPMENT Test handset ........................................................................................................................................ 13 Testlamp .............................................................................................................................................. 14 Dial speed and pulse ratio test set .................................................................................................... 15 Type 31 portbble dial speed test set ................................................................................................ 16 Buzzer test set ...................................................................................................................................... 17 Teststand ............................................................................................................................................ 18 . . CHAPTER 3 MAINTENANCE TOOLS AND MATERIALS Maintenance tools. materials. and supplies ..................................................................................... 19 Maintenance spare parts .................................................................................................................... 20 General ................................................................................................................................................. 21 Methods of destruction ...................................................................................................................... 22 Destruction of components ................................................................................................................ 23 . .... APPENDIX REFERENCES ............................................................................................................................................................... e iii CHAPTER 1 INTRODUCTION Section I. GENERAL 1. Scope These instructions are published for the informa. tion and guidance of personnel to whom this equip, ment is issued. They contain basic information on the special tools, test equipment, and common supplies required by operating and maintenance personnel in a typical step-by-step dial central office. They list and describe briefly the special tools, test sets, installation materials, and maintenance spare parts supplied initially by the manufacturer, as well as the common tools, standard test sets, and general maintenance materials obtained through regular supply channels. by the Army will be filled out and forwarded through channels to the Office of the Chief Signal Officer, Washington 25, D. C., when trouble occurs more often than is normal, as determined by qualified repair personnel. (3) A F Form 54 (Unsatisfactory Report) for equipment used by the Air Force will be filled out and forwarded to Commanding General, Air Materiel Command, WrightPatterson Air Force Base, Dayton, Ohio, in accordance with A F Regulation 15-54. b. Use other forms and records as authorized. 2. Forms and Records 3. References a. The following forms are used in reporting receipt, operation, and maintenance of the equipment : (1) NME Form 6 (Report of Damaged or Improper Shipment) for equipment used by Army Field Forces and technical services will be filled out and forwarded in accordance with SR 745--45-5 or AFR 71-4, when equipment is received in a damaged condition or when it is necessary to report unsatisfactory preservation, packaging, packing, marking, loading, unloading, and handling of supplies. (2) DA AGO Form 468 (Unsatisfactory Equipment Report) for equipment used This manual is one of a series of 15 technical manuals dealing with the equipment which comprises a typical step-by-step dial central office. Detailed information on the operation, maintenance, and installation of this cent~aloffice equipment is given in the other manuals of the series, listed in the appendix. The appendix also contains a list of current references, including supply catalogs, technical manuals, packaging specifications, and other available publications. I n addition, it lists the forms required for use by using personnel in the performance of prescribed operations. General maintenance procedures and routines involving the use of tools, test sets, and supplies described in this manual are covered in TM 11-2103. Section II. DESCRIPTION AND DATA OF TEST EQUIPMENT 4. General M o d step-by-step dial central offices are equipped with a type 1 wire chief's test desk, which provides centralized testing facilities for the maintenance of both the central office and outside plant equipment, and with several portable test sets for routine testing of the central office switching equipmelit. These test sets include a connector routine test set, a currentflow test set, and a test handset. Other test equip- ment, sometimes required by dial central office maintenance men or by outside plant repairmen, can be'obtained through regular supply channels. 5. Type 1 Test Desk The wire chief's test desk is the major center for fault location and equipment tests in a typical stepby-step dial central office. Although additional test sets. are used in the central office, most basic tests 1 can be performed from the test desk. Detailed information and operating instructions on the type 1 test desk are given in TM 11-2110. Other tools and test equipment used in dial central office maintenance are described in TR!I 11-372 and TIT 11-487. The following test equipment components and circuits comprise the type 1test desk: a. VOLT-OHM-MILLIAMMETER. This multirange meter has ranges of 0-15, 0-150, and 0-600 volts, 0-150 and 0-600 milliamperes, and 0-5,000, 0-50,000 and 0-500,000 ohms. I t is used primarily as a continuity tester in determining the nature and extent of electrical faults within the central office. b. WHEATSTONE BRIDGE.The Wheatstone bridge is a precision resistance bridge which has a range of 1ohm to 10 megohms. I t is used to make generalpurpose resistance measurements and to detect cable faults in the outside plant equipment. c. DIALSPEED AND PULSE RATIOTESTSET. This test set measures dial speeds in pulses per second and the percent make (pulse ratio) of dial pulse spring contacts.. d. HOWLERAND INSULATION BREAK-DOWN TEST CIRCUIT.The howler circuit provides a loud tone to signal a telephone user when a handset is left off the cradle and no call is in progress. The insulation break-down test circuit is used to test telephone lines for break-down of insulation upon the application of a high potential. e. TEST CORDAND TEST TRUNKCIRCUITS.The test cord cir&its connect the test desk to the desired test trunks. The test trunks circuits permit direct connection for test purposes from the test desk to any telephone line of the central office. f. NIGHTALARMCIRCUIT.The night alarm circuit provides an audible alarm, or buzzer sound, on incoming calls during night service or periods when the test desk is unattended. y. IN-CALLAND OUT-CALL WIRE CIRCUITS.These call-wire circuits permit intereommuizication between two or more test desks or between a test desk and an illformation center, repair center, or switchboard. theory of operation and operating instructions for the connector routine test set are covered in TM 11-2113. This test set checks the following functions of connectors and reverting-call switches : (1) Connector f u n c t i o n s tested. The connector routine test set tests the following functions of connectors : (a) Vertical and rotary stepping from pulses over a high-resistance loop. ( b ) Vertical and rotary stepping from pulses over a loop having low leakage resistance. (c) Returning busy tone when stepped to a busy line. ( d ) Extension of ringing current to the called line and ring-back tone to the calling line when the wipers are stepped to an idle line or trunk. (e) Completion of the talking circuit over an idle line or trunk. 6. Test Sets Supplied by the ~anufclcturer a. CONNECTOR ROUTINETESTSET. The connector routine test set (fig. 1) is used for the routine testing of the regular conneetors, PBX (Private Branch Exchange) connectors, and revei-ting-call switches in a typical step-by-step dial central office. Detailed TM 2111-1 Figure 1. C o n n e c t o r routine t e s t set. flow test set. This test he1 rucAilqnresthc clcctriccrl opo.ntc value, or specified minimum cnrrcnt through the relay windings to oprrnte the relay. a n d the elcclra'cal ?to,ioprrntc ralur. or the masiinmn current, flow throng11 the windings witllont operating the relay. I t consists of sets of adjnstable rrsistanrc~bnlllis, n millinmmetcr, and siiit;~l)lcopcwting controls. The resistancc b;inlrs arc arljnsted mitil tllc nlarginal opclrrrfcand ~ i o t t o l ~ w n f c current-flow values arc intlicatcd on the milliammctcr. in accorclauc~cwit11 circuit rcqni~.emenl tal~lcs or ~ ~ c l i l y atlji1stmc1nt sllcets prcpnrccl by the mannfi~ctnrcr. The operate anc1 nonopcrate test. pctnformrd n-it11 Ihc cnrrcl~t-flow test sct, givc.s :111 accuriltc indicatinl~.of t hc opol~ating (~fficiency of relays. IVhcn rcatl.justing a rcnlay, rising the cnrrent-flow t-cst s ~ t .thv r(bl;ly contirct sprir1g.q arc ten- ( J ) Release U I I I I V ronncctor u-ht~nthe last (calling or callrcl) party llangs up. ( 2 ) Rrt*~rfing-en11 szc.ifelr f 1oictiolt.s t c s f f d .The following f ~ u ~ c t i o n sof reverting-c a l 1 switches are chedrccl 1)y tlic coniiector routine test set : ( ( 1 ) Pnlsinq over a loop ~-11icl1has a rcsistnnce hieher thiln normal to seize n rcvcrting-call switvh. ( b ) Revertirlg-(*a11riiigillr o w r n line which lias a higher than normal rec;istaiice. ( c ) Ringinn cut-off wllcn callccl party answers. ((7) Rcletlse when the last p i ~ r t \ -hillin.; 11p. b. C U R R E S T - F I , TEST ~ ~ 'SET. ( 1 ) dl)plicrrtiorr. Rela\-s iisctl in step-by-step dial rcntral officck c.clnil)mcnt are tcstccl nil adjustctl in accortiancc n-it11 electrical l)erf'ornii~ncc~ rtlcluirrmcntq 1)y il c ~ i r r c n t T T - ,' SW LOCK 4ON-OPERA1 jW ROW T. RMS. X EXT RMS. T TEST RMS. t H 0 9 T PUSH IUTTON RESISTANCIZ RANGE SW N OPR - C )PA RELAY T EST SW ' B A T T CUT-OI 'F METER REVERS ING SW sW \ st MI "' LItL-0 - F i : ~ r t ~ ,9. c ('ro.r/ 111-flail. t r s t t. sioned and adjusted until the relay meets the operate and nonoperate current-flow requirements. This operation is sometimes called mnrgining. (2) T!ypical current-flow fesf set. A typical current-flow test set used in many stepby-step dial central offices is illustrated in figure 2. The milliammeter of this test set corers current-flow ranges of 0-30, 0-150, and 0-750 milliamperes; the resistance banks are adjustable in h h m steps from 5 to 22,215 ohms. An auxiliary 20,000-ohm resistor increases tlie resistance range to 42,215 ohms. Provision is made also for connecting esternal resistors of any dcsired resistance value in series with the resistance banks. Lei-er switches (keys) control the resistance value and milliammeter ranges. Special test cords for connecting the test set to the contact springs of relays are usually included with the cnrrent-flow test set. TJI 11-2112 describes the operation and nse of the current-flow test set. S o t c . Standard Current-flow Test Set 1-181 (par. 8 b ( 5 ) ), wliicl~can be obtained through regular supply el~m~ncls, may Ile used instead of tlie current-flow t c s t set furnished b y the mmluf acturer. -.--.- - - 7 c. STEPPISG-SWITCH TESTSET. This test set is an automatic interrupter which generates pulses for use in testing the vertical stepping of selectors, tlie vertical and rotary stepping of connectors, and the action of pulse repeaters, all under simillated loop resistance and leakage conditions. The stepping-switch test set (fig. 3) is also called imp~rlse testing machine, varying ntacltine, interrupter mac l ~ i n e ,dial pulse generator, and test pulse nlackine in the manufacturer's literature, specificat,ions, and drawings. I n relatively large step-by-step dial central oficcs, this test is used widely for fast and accnrnte routine testing on selector and connector s~ritcl~ shelves, thereby eliminating the necessity for dialing test digits for each switch tested. This saves time mlien larqc numbers of switches must be tested, siilce three digits are required for testing 200-point connectors with test sets, such as the test handset (par. 'in), ~vhichrequire dialing to produce test pulses. I n smaller step-by-step dial central offices, ho~vevcr,this test set generally is not used for routine testing. I n this case, the connector routine test set is preferred by repairmen for checking the stepping action of connectors while the test handset is preferred for checking the stepping action of selectors. Use of the stepping-switch test set in smaller offices is limited to the repair or readjustment of the - - -. - -- -.--m --*--" EXTENSION S W ITCHBOX . SlON Figtire 3. Stepping-stc.itclr test set. AT. CABLE TI 12114-2 DIAL AND (RECEIVER HOUSING Figure 4. Test handset. stepping mechanism of the selectors and connectors. TM 11-2114 describes the application, functioning, and operating procedure of the stepping-switch test set. 7. Other Test Equipment Supplied by the Manufacturer a. TESTHANDSET. The test handset (fig. 4) is a test telephone having a transmitter at one end and a receiver and dial mounted back to back at the other end. I t is used for dialing, monitoring, and talking tests on the switching equipment of a typical step-by-step dial central ofice. There are two push switches (push buttons), marked C and R on the handle of the handset, which are located just below the dial and receiver. The test handset is also equipped with a test cord and special test plug which mates with the test jack terminals of the switch to be tested. b. TEST LAMP. A small test lamp (fig. 5) for continuity testing is provided with the step-by-step dial central office maintenance tools supplied by the CLIP FOR TEST CONNECTION OR # BV SWBD LAMP Figure 5. Test lamp. *il manufacturer. The unit consists of a lampholder, a test prod, and a 6-foot test cord with a special clip for connecting to the relay contact springs: A 48volt telephone switchboard-type lamp is ordinarily used in this test unit. The lamp filament resistance, when cold, is 185 ohms and, when hot, varies between 1,260 and 1,500 ohms. 8. Signal Corps Standard Test Equipment Additional items of test equipment, which are not supplied by the manufacturer, may sometimes be required in the maintenance and repair of step-bystep dial central ofiice equipment or the outside plant equipment. For additional information on this test equipment, which is usually obtained through regular supply channels, refer to TM 11487 and TAI 11-372. The standard test sets which are obtainable from regular supply channels and which are used most commonly in the maintenance of the equipment of a typical step-by-step dial central office are listed below. a. TESTSET TS-19O/U. This is a high-resistance test receiver, having a headband and a three-conductor test cord. The test receiver has a 1,000-ohm impedance. An external 50,000-ohm resistor normally is connected in series with the receiver. A switch cuts out this resistor when it is not required. The test set is equipped with a three-conductor test cord, an alligator clip, and a test prod for probing in a circuit. Test Set TS-19O/U is used for making trouble location tests, for continuity testing, and for checking circuits for the presence of negative battery or ground. The 50,000-ohm resistor protects the user against loud clicks when testing for potentials in circuits, and provides a high-impedance monitoring circuit to bridge across circuits without affecting performance. The test receiver may be used when identifying cable pairs, since its high resistance will not operate or restore any relays in the equipment. For details concerning the use of Test Set TS-19O/U in the maintenance of equipment in a typical step-by-step dial central office, refer to TM 11-2103. b. PORTABLE TEST SETS. The following pontable test sets, when available, are used frequently in the maintenance and repair of step-by-step dial central office equipment : (1) Voltohmwzeter 1-166. This test set is a portable self-contained multirange voltohmmeter for measuring a-c and d-c voltages and resistances. Operating instruc- tions for this instrument are given in TM 11-2613. (2) Test Set TS-26/il'SM. This instrument is a portable, fault-locating test set, which contains a 45-volt test battery. It measures d-c voltages and resistances. Operating instructions for Test Set TS-26/TSM are contained in TM 11-2017. (3) Test Set TS-27/TSM. This test set is a form of Wheatstone bridge used for line tests, but is equipped, in addition, with a vacuum-tube oscillator which supplies 20cycle current for capacitance tests and fault location. Operating instructions for Test Set TS-27/TSM are outlined in TM 11-2057. (4) Test Set 1-49. This instrument is a portable, self-contained Wheatstone-bridge test set, especially adapted for locating faults in communication circuits. I t differs slightly from the Wheatstone bridge which is part of the type 1test desk used in nlany step-by-step dial central offices. Refer to TM 11-2019 for operating instructions and fault-locating procedures for Test Set I49. ( 5 ) Test Set I-48-B. This instrument is a portable insulation-resistance test set with a range from 0 to 1,000 megohms. Operating instructions for Test Set I-48-B are given in TM 11-2050. (6) Test Sets I-61-A, I-61-B, nmd I-614. These test sets are portable, self-contained, transmission-measuring units, incorporating an audio oscillator for sending, an amplifier for receiving, and a power-level meter. Test Sets I-61-B and I-61-C also include a local-battery Telephone EE-8-B. Operating instructions for these test sets are found i11 TM 11-346. (7) Cable fault-locating equipment. Refer to TM 11-372 and TM 11-487 for information on Test Set 1-51, WECo Test Set 62-A, WECo Test Handset 1011-BW, Test Set TS-420/U, and other equipment used in the testing of outside plant equipment. (8) Test Set 1-181. This portable, standard current-flow test set is used in testing and adjusting relays of step-by-step dial central office switching equipment, in accordance with the manufacturer's electrical ~ specifications. Its continuously variable resistance range makes this test set especially suited for precision testing and adjusting of relays, since the current-flow test set furnished by the manufacturer (par. 6b) has its resistance range in 5-ohm steps. Two control knobs in each resistance path of this standard test set provide a coarse setting and a fine adjustment which permit accurate measurement of the marginal current-flow requirements. For details concerning the operation and use of Test Set 1-181, refer to TM 11-2036. Test cords and connectiiig tools, as listed in TM 11-2036, are required for use with Test Set 1-181, but are not provided as part of the test set. ( 9 ) l'est Xets 1-242 and I-142A. These test sets incorporate a number of relatively independent test circuits for measuring the electrical characteristics of step-by-step dial central office equipment. Detailed information on Test Sets 1-142 and I142A is contained in TM 11-2062. It includes the following test circuits: ( a ) Measzcring circuit. A variable-range, vacuum-tube type volume indicator is used for-measuring the electrical output of telephone transmitters or receivers. ( b ) Capacitor test circuit. A relasationtype oscillator is used to check the leakage resistance of capacitors. ( c j Generator tesl circuit. This test circuit is nsed for checking the electrical rating of generators used in central offices. ( d ) Ringer test circuit. This circuit consists of a hand-operated generator and resistors arranged to supply minimum operating currents of approximately 162/3 cps (cycles per second) to ringers of three different impedances. ( e ) Znsz~lationresistance test circuit: This test circuit 'measures resistances of 1 megohm or less. ( f ) Dial test circuit. This test circuit measures the speed of the dial pulse spring contacts and the percentage of the total pulse period during which the dial pulse spring contacts are closed (pulse ratio, or percent make, of the dial pulse spring contacts). ( g ) Continuity test circuit. A buzzer and lamp are provided in this test circuit for making point-to-point tests for electrical continuity. ( h ) Instrument test circuits. These circuits are provided for testing the efficiency of common- and local-battery telephones. 9. Dial Speed and Pulse Ratio Test Set A portable dial speed and pulse ratio test set (fig. 6) is used by installation and maintenance men to check the speed and pulse ratio, or perceiit make (ratio of the tiMe the dial pulse spring coiltacts are closed to the length of the pulse period), of dials of telephone sets. This test set usually is included with the installation tools which are furnished by Figure 6. Dial speed a n d pulse ratio t e s t set. 7 the manufacturer with the dial central office equipment. I t may be used to make dial tests at the point of installation, but it is more adaptable for use at test and repair benches. The speed of dials must be within certain limits to m u r e proper functioning of stepping switches which are actuated by dial pulses. A dial speed of 10 pulses per second is considered ideal, while extreme test limits for dial speeds are 8 and 14 pulses per second. Normal percent make, or pulse ratio, of dial pulse spring contacts is approximately 38% per cent. The test set also can be used to make rapid approximations of the pulse ratio of a short series of dial pulses (par. 17c (3) ) . A milliammeter on the front panel of the test set registers both dial speeds and percent make of a series of pulses. This milliammeter has two scales, one for dial speeds, calibrated from 0 to 15 pulses per second and the other for pulse ratios, calibrated from 0 to 100 percent make. The dial speed and pulse ratio test set (fig. 6) is set normally for percent make tests. To use the test set as a dial speed indicator, SPEED-SET FULL SCALE switch must be operated to the SPEED position. 10. Type 31 Portable Dial Speed Test Set (fig. 7) a. GENERAL. For efficient operation of the switching equipment in a step-by-step dial central office, the speed of rotation of telephone dials must be kept at approximately 10 pukes per second. Therefore, test equipment for the accurate determination of dial speeds is required by dial central office maintenance men. Thus, wire chief's test desks in newer central offices are equipped with dial speed and pulse ratio testing equipment which can Figure 7 . Type 31 dial speed test set. be used both as a dial speed indicator and a dial pulse ratio (percent make) test set. A portable dial speed and pulse ratio test set (par. 9) is also furnished initially by the manufacturer with the newer dial central office equipment. The type 31 portable dial speed test set (fig. 7) is used in some older central offices. The components of this test set are incorporated in older models of the type 1 test desk, used in some earlier step-by-step dial central ofices. It consists of two relays, a stepping magnet, a circuit-breaker, a single-throw, locking-type lever switch, and a spring-driven timing mechanism which moves the pointer from left t o right on the indicator scale. The test set is mounted on a laminated panel which is faced and backed with bakelite. The unit is mounted in a wooden carrying case by means of four wood screws. The dial speed indicator, the lever switch, and four binding posts (marked T, R, +GND and -48) are mounted on the front of this panel. The two relays, equipped with individual dust covers, and a 3-ampere, cartridge-type fuse are mounted on the rear of this panel. The type 31 dial speed test set operates from an external 48-volt battery supply, connected to the two lower binding posts (+GND and -48) on the front of the panel. b. APPLICATION. Type 31 dial speed test set is used as a portable testing unit for repairing or ad- justing dial mechanism of dial telephone sets. I t is furnished as part of the installation tools provided by the manufacturer. When used at a repair or testing bench, the test set is useful in making dial speed tests on dial telephone sets prior to installation. I t is used by installer-repairmen to check and test dials. I t may be used also for completing dial tests at the attendant's switchboard if the installation of the test desk has not been completed. 1 1. Buzzer Test Set A portable buzzer test set (fig. 8 ) operated by two l$4-volt, dry-cell batteries (BA-23), usually is included with the installation tools which are furnished by the manufacturer. The buzzer and the batteries are contained in a wooden case. The buzzer test set is used during cabling and wiring of the step-by-step dial central office equipment to identify cable conductors and t o test and verify the wiring after the installation is completed. A buzzer test set similar to that illustrated in figure 8 is a necessary item in step-by-step dial central office maintenance. If not available, buzzer test sets can be constructed locally. The buzzer test set and a switchboard plug are used in making continuity tests on switchboard multiple cables during installation. Figure 8. Buzzer test set. 12. Test Stand A special test stand (fig. 9 ) is supplied with the step-by-step central office maintenance tools furnished by the manufacturer. The test stand is used to support two-motion stepping switches when removed from the shelf positions for adjustment or repair. A 24-terminal test jack is included on the test stand for making connections to negative battery and ground. This permits operating tests to be made on stepping switches while mounted on the test stind. Bayonet pins i n the upright members of the test stand support switching units which have a large mounting base. Smaller mounting bases are supported on the test stand by screws inserted in tapped holes in the upright members. F i p w 9. Test s t c ~ t d . CHAPTER 2 OPERATING INSTRUCTIONS AND THEORY OF OPERATION FOR TEST EQUIPMENT 13. Test Handset (figs. 4 and 10) (j) After testing all idle linefinders in the B group, momentarily operate the group relay busy switch of the B group. Then restore the B group busy switch to transfer back to the A group of linefinders. Make sure that the linefinder equipment transfers both ways, from the A to the B group and then back to the A gronp. (2) Selector trunk test. Test selectors in groups of ten with the test handset as follows : + a. OPERATING INSTRUCTIONS. (1) Linefinder operation test. Perform routine testing of linefinders with the test handset as follows : (a) Plug the handset test cord into the two bottom springs of the test jack associated with the A group of linefinders. Note that one of the linefinders in the A group steps its wipers to the contacts on its banks which correspoild to the test line (No. 29). (b) Listen to the test handset receiver for dial tone. (c) On hearing dial tone, hold push switch R operated and dial any digit corresponding to a vacant, or unused, selector bank level, as shown on the central office cabling diagram, or on the selector terminal assembly drawing. Listen for busy tone. Release push switch R. (d) Operate push switch C on the handle of the test handset. The linefinder which mas seized previously ( ( a ) above) releases upon operation of switch C. (e) Release push switch C on the test handset handle. The next idle linefinder should step its wipers u p to the contacts on its banks which correspond to the test line (No. 29). (f) To test all other idle linefinders in the A group, repeat steps described in (a) through ( e ) above. (g) When all idle linefinders in group A have been tested, operate the group relay busy lever switch (key) of the A group. ( h ) Restore the group relay busy switch of the linefinders A group. (i) Make a similar operation test of each idle linefinder in the B group of linefinders from the B gronp test jack by repeating steps described in ( a ) through ( f ) above. ( a ) Insert the handset test plug in the two top selector test jack springs. ( 6 ) Hold push switch R operated and dial any test digit. Observe whether the selector steps its wipers up to the dialed level and around to the contacts of the first idle trunk. (c) Rapidly open and close the VON (vertical off-normal) springs and note that the selector shaft steps its wipers around to each trunk on the dialed level. If an open trunk is encountered, the shaft will fail to rotate. ( d ) Listen for busy tone each time the selector wipers reach the eleventh rotary step. (e) Test each selector bank level in a similar manner. On vacant levels, the selector wipers should rotate to the eleventh rotary step and return busy tone. ( f ) Test all trunks on all selector levels, using a diffcrenb group each time the test is made, so that ultimately all groups will be tested. ( 3 ) Xelector cut-in and release test. Perform this selector test using the test handset as follows : ( a ) Plug the handset test cord into the two top test jack springs of a selector. ( b ) Holding push switch R of the test handset operated, dial a digit which will cause the selector to step its wipers up to the bank level being tested. (c) Observe that the selector wipers cut in properly and rotate to the first idle trunk on the dialed bank level. (d) Dial the digit 1 to insure that the line switching relay of the selector has operated properly. Failure of the line switching relay will be indicated by a vertical kick of the shaft when the second digit is dialed. Release test handset push switch R. (e) Observe that the selector releases properly upon disconnection. (f), Test a different bank level at each inspection to insure that the selector wipers will beqtested ultimately on all bank 1e;els. (4) Two-way repeater trunk test. Test each two-way repeater with the test handset as follows : (a) Plug the test handset into the top and bottom test jacks of the repeater and operate push switch C on the handset. Monitor the trunk to determine whether the trunk is idle. (6) Holding push switch R of the handset operated, dial the reverse battery number in the distant central office and listen .for a click in the handset receiver. (c) When the reverse battery click is heard, proceed to the next repeater. Test repeaters to manual central offices by dialing the operator. (d) Release push switch R and operate push switch C of the test handset. This permits the trunk equipment to release. (e) Busy out any repeater which fails to meet the test outlined in the steps described in (a) through (d) above, and notify the distant central office of the trunk in trouble. (f) Make a note of all busy trunks and test each one when it becomes idle. b. THEORY OF OPERATION.The test handset circuit (6g. 10) consists of a telephone transmitter, receiver, dial, an induction coil, a 0.43-microfarad capacitor, a 1,200-ohm resistor, and push switches C and R. Plugging the test handset into the test jack of a stepping switch closes the loop to that switch, making the switch busy to other calls and preparing it for dialing or talking tests. Push switch C, when in the unoperated (closed-contact) position, normally short-circuits the 0.43-microfarad capacitor. When held operated, however, push switch C opens the transmitter circuit and forms a listening circuit through the capacitor and receiver in series. This permits the testman to monitor on busy equipment. To talk with a called party on the loop, the testman releases push switch C, thereby closing the transmitter circuit again. Similarly, push switch R normally short-circuits the 1,200-ohm resistance. When the testman holds push switch R operated, the short circuit is removed and the resistance is connected in series with the loop. This provides a standard 1,200-ohm test loop over which dial pulses from the test handset dial may be sent to test the stepping action of the stepping switch under test. The 1,200-ohm resistance in series with the loop simulates the extreme limit of loop resistance for test purposes. The test handset may be adapted for other tests by disconnecting the special plug from the test cord, and using test clips, terminal lugs, or standard telephone plugs, which permit connection of the handset to other equipment. XMTR TM2103-II Figure 10. Test handset, schematic diagram. 14. Test Lamp (fig. 5 ) a. OPERATINGINSTRUCTIONS. Make continuity tests with the test lamp on relay circuits of the stepby-step dial central office switching equipment as follows : (1) To test the continuity of a relay circuit which is connected to ground, but not to negative battery, connect the test clip of the test lamp to a negative-battery source and make point-to-point exploratory tests with the test prod. Lighting of the test lamp will indicate the presence of ground in the circuit. (2) When the relay circuit under test is connected to negative battery, but not to ground, connect the test clip to ground and make continuity tests with the test prod. The presence of negative battery in the circuit is indicated by lighting of the test lamp. (3) If the relay circuit is not connected to negative battery, or ground, connect the test clip in series with the central office battery and perform continuity tests with the test prod. ' ( 3 ) To calibrate the test set initially for dial speed tests, operate the SPEED-SET FULL SCALE lever switch to the SPEED position (fig. 6) and adjust the SET FULL SCALE control knob until the meter registers an average dial speed reading of 10 pulses per second. (4) Dial, or instruct the telephone user or the repairmen at the distant dial telephone set to dial, the digit zero ( 0 ) . (5) Read the speed of the dial under test directly on the meter scale (fig. 6 ) . A meter reading of 8 pulses per second or lower indicates a slow dial speed; a meter reading of 14 pulses per second or higher indicates a fast dial speed. When readjusting dials, try to obtain a dial speed reading of 9 to 11pulses per second. b. THEORY OF OPERATION. The test lamp circuit, used in point-to-point localization tests, consists of a lamp with a thin metal probe, or test prod, at one end, and a length of flexible cable terminating in a test clip at the other end. The test clip is connected . to known ground or negative battery, while the test prod is used in tracing circuits point by point. The presence of ground or negative battery in a given b. PERCENT MAKETEST. TOperform pulse ratio, circuit under test is shown by the lighting of the or percent make, tests with the dial speed and pulse test lamp. When the test prod touches each point ratio test set, proceed as follows: in a circuit connected to ground, it completes the lamp circuit from ground through the lamp to nega(1) To calibrate the test set initially for pertive battery thus lighting the lamp. Similarly, negcent make tests, operate the SPEED-SET ative battery can be traced from point to point in FULL SCALE switch temporarily to the any circuit. I n each case, a continuous circuit is SPEED position and adjust the SET required to light the test lamp. Failure of the FULL SCALE control knob for full-scale lamp to light indicates an open circuit. deflection of the meter pointer. 15. Dial Speed and Pulse Ratio Test Set (figs. 6 and 11) a. OPERATINGINSTRUCTIONS FOR DIAL SPEED TESTS. TO use the dial speed and pulse ratio test set as a dial speed indicator, proceed as follows: (1) Connect the dial telephone set being tested to the P I and G binding posts of the test set (fig. 6). Connect a jumper wire between the negative (-) and P2 binding posts of the test set. (2) Connect the 48-volt battery supply of the central office to the positive (+) and negative (-) binding posts of the test set (fig. 6 and A in fig. 11). When using the test set at an outside telephone set which has no battery supply available, connect the telephone line to the positive and negative binding posts, and request the central office testman to*supply negative battery over the line. If the test set is being used at the central office for dial tests over the telephone lines, connect the line which is being tested to the P1 and G binding posts. (2) Hold. the PRESET READING lever switch operated temporarily, and adjust the PRESET READING control knob until the meter pointer reaches full-scale deflection. (3) Release the PRESET READING lever switch. (4) Dial, or request the telephone user or the repairman at the distant dial telephone set to dial, the digit zero. The