Manual / Guide · c. 1929-1950s
Technical Bulletin 405: Test Turret Type 21
AE Type 21 test turret: description and circuits of the exchange test desk used to test lines and switches.
Manual / Guide · c. 1929-1950s
AE Type 21 test turret: description and circuits of the exchange test desk used to test lines and switches.
TEST TURRET TYPE 21 Technical bulletin 405 New factory, development laboratories, and general ofice at Northlake, Illinois, US.A. AUTOMATIC ELECTRIC COMPANY is an organization of designing, engineering, and manufacturing specialists in the fields of communication, electrical control, and allied arts. For More than sixty years the company has been known throughout the world as the originator and parent manufacturer of the Strowger Automatic Telephone System. Today Strowger-type equipment serves over 75% of the world's automatic telephones. The same experience and technique that have grown out of the work of Automatic Electric engineers in the field of telephone communication are also being successfully applied on an ever-increasing scale to the solution of electrical control problems in business and industry. PRINCIPAL PRODUCTS Strowger Automatic Telephone Systems-Comfor explete automatic central-ofice equipment - change areas of any size, from small towns to the largest metropolitan networks. Community Automatic Exchanges-Unattended automatic units for small rural or suburban areas, w i t h f a c i l i t i e s f o r s wi t c h i n g i n t o a t t e n d e d exchanges. A u t o m a t i c T o l l Boards-An adaptation of Strowger principles to toll switching, resulting in simplification of operators' equipment and greater econon,y of operating and toll-circuit time. P r i v a t e A u t o m a t i c Exchanges-Available in various capacities, with or without central-office connections, and with facilities for special control services to meet the needs of the user. P.B.X. Switchboards-A complete range of cordless and cord . types for the modern business. . T e l e p h o n e Instruments-Modern designs for automatic or manual exchanges, including t h e Monophone-the world's most attractive and eficient handset telephone. Exchange Accessory Equipment-Auxiliary exchange and substation equipment, including manual desks, testing apparatus, transmission eauiameut. and all accessories needed for t h e - operation and maintenance of the modem telephone exchange. Makers also of electrical control apparatus f o r ipdustrial, engineering, and public utility companies, telephone apparatus f o r railroads and pipe-line companies, private telephone systems of all types, electrical and communication devices f o r aircraft and airways control, and special communication apparatus f o r military a n d naval departments. CONTENTS Page 1. INTRODUCTION ................................ 1 DESCRIPTION .............................. 1 2.2 T e s t f a c i l i t i e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2.3 Optional t e s t equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.4 A l a r m s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.5 Keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.6 L a m p s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 3 General design . PROCEDURE O F OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 R e g u l a r line equipment .......................... 5 ............................. 6 3.3 T e s t d i s t r i b u t o r . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.4 V o l t m e t e r t e s t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.5 T e s t i n g l i n e c i r c u i t o v e r t e s t l i n e s . . . . . . . . . . . . . . . . . . . . 8 3.6 M i s c e l l a n e o u s t e s t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2 Inspector's trunk . . . . . . . . . . . . . . . . . . . . . . . 11 G e n e r a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 . EXPLANATION O F OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 11 Trunk to t e s t distributor . . . . . . . . . . . . . . . . . . . . . . . . . 12 R e g u l a r l i n e equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 1 3 T r u n k t o M.D.F. (jackbox) . . . . . . . . . . . . . . . . . . 14 Inspector's trunk circuit . . . . . . . . . . . . . . . . . . . . . . . . . 14 Voltmeter tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 D i a l t e s t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Miscellaneous c i r c u i t f e a t u r e s . . . . . . . . . . . . . . . . . . . . . . 16 T e s t c o r d s (trunk t o toll switchboard) RESISTANCE TABLE I "VM SHUNT" K E Y NORMAL (NO SHUNT) . . . . . . . . . . . . . . . . . 17 RESISTANCE TABLE I1 "VM SHUNT" KEY OPERATED (VOLTMETER SHUNTED BY 1.010R) . . 18 Type 21 Test Turret TEST TURRET TYPE 1. INTRODUCTION The type 21 t e s t t u r r e t is designed f o r making the t e s t s required for maintaining s m a l l autom a t i c exchanges. It is effectively used in exchanges of 1000 lines o r l e s s , o r in P-A-Xs of any size. The attendant's operations of the t u r r e t cons i s t of operating panel controls and evaluating the r e s u l t s . Visual aids, such a s supervisory l a m p s and m e t e r s , a s s i s t the attendant in making t e s t s . The manipulation of panel-controls and the explanation of e l e c t r i c a l operation a r e included in this text. The t e s t s that a r e normally used a r e described and the explanation of operation will enable the t e s t attendant to improvise additional t e s t s . 2. DESCRIPTION 2.1 General design. The type 21 t e s t t u r r e t c o n s i s t s of a cabinet for housing the equipment, and a c h a s s i s containing the apparatus and wiring. The cabinet is ordinarily made of mahogany with a d a r k finish, other woods and finishes Figure 3. can be furnished on special o r d e r . The cabinet s i z e is 14-1/2" high, 21-112'' long, and 14-518" deep. It m a y be mounted on a n office desk o r table. It weighs 66 pounds. The t e s t t u r r e t components a r e assembled to provide e a s y a c c e s s to the wiring and apparatus. The r e l a y s a r e mounted upon a swinging gate. With the gate swung open the r e a r wiring is accessible on e i t h e r side and the r e a r of the front panel may be easily reached. External cable e n t e r s through a hole in the baseboard and passes to a terminal block where it will be connected to the t e s t circuit. 2.2 T e s t facilities 2.2.1 T e s t c o r d s . The test t u r r e t can be equipped for two trunks to a manual board. At the manual equipment, these trunks terminate a t t e s t c o r d s o r t e s t jacks. These trunks a r e available for making various t e s t s through the switchboard. 2.2.2 Selector level trunk (inspector's trunk). The t u r r e t is equipped with one inspector's trunk incoming f r o m a selector level, which provides the,.means for inspectors, i n s t a l l e r s , and repairmen, to dial in and talk with the t e s t attendant, and a l s o provides the attendant Turret un'ring. Figure 2. Type 21 test turret, rear view (cabinet removed). with connections f o r t e s t purposes. The trunk is c l e a r e d of attachments and is connected to the t e s t c i r c u i t for making t e s t s when the attendant a n s w e r s . 2.2.3 T r u n k s to Main Distributing F r a m e o r t e s t distributor. The t e s t t u r r e t is wired and m a y be equipped with facilities for four trunks to the M.D.F. a n d / o r t e s t distributors. 2.2.3.1 T r u n k s to Main Distributing FrBme (figure 3). Ordinarily, i t is desirable to have a t l e a s t one trunk to the M.D.F., to establish connections which cannot be established via the t e s t switch train, and for performing special o r routine t e s t s , without tying up the switch t r a i n . F o r example, t e s t connections to trunk lines f o r making m e t e r m e a s u r e m e n t s , cannot be obtained through the t e s t switch train, because the t e s t connectors have a c c e s s At the M .D .F . provision is made f o r connecting a test shoe to the trunk. The t e s t shoe s p l i t s the inside plant f r o m the outside plant, permitting t e s t s to be made on e i t h e r the inside o r outside. 2.2 -3.2 Trunks to t e s t distributor. T h i s trunk gives the testman a c c e s s to the t e s t switch t r a i n via the test distributor. By m e a n s of the t e s t switch t r a i n the testman h a s a c c e s s to and can test through the connector t e r m i n a l s of local lines. 2.2.4 Voltmeter. The t e s t t u r r e t is equipped with a 0-75 volt d i r e c t c u r r e n t voltmeter of 100,000 ohms (R) internal r e s i s t a n c e , for making t e s t s on outside cable p a i r s . &IN ClSTRlBUTlffi FRArE PROTECTOR NAIN DISTRIBVTING FRAME TEST CORD AHD SHOE I Jbcr sox I only to the line t e r m i n a l s . Connections to trunk lines, however, a r e e a s i l y made via the M.D .F. with a t e s t shoe. I I TO THE TRUNK. TO THE LD.F.. OR TO THE TEST . n 111 c m . c w t o 1 7oS I 1 I 11 h0TE I _- . - LINE OUT OUT -nc WtiEN JACK EOXES &RE NOT PROVIDED, THE *IRING IS THEN CONNECTED DIRECTLY TO THE TRLNK. TO THE M.D.F.. OR TO THE TEST DlSTllleUTOR Figure 3. Connection of jackbox to Main Distributing Frame. TEST CORDS SEL LEV TRK TRKS TO TEST DIST. I 2 SPOTTER 3 CEN. PULSE 4 SUPY 0 0 0 0 0 0 0 0 0 0 0000000000aD b c o OUT TALKL TEST TEST 2 HOWL HC OR HC OR RLS CON1.I RLS CONN OUT i HC OR RLS C O W CUT Y VM HC OR RLS C O N TEST N A FA TRANS BAT. BAT. TEST I 4 b M F SHUNT GRD R ' LINE SW VM TAM DIAL HOLD HOLD HOLD HOLD REV DST RING BCO 0 $ SET FULL SCALE PVL S E TEST b + 4 d 4 ? d h d + T"f& 0 5 WLSE 3 0 0 2 , Figure 4. Key mounting and designations. 2.2 -5 Auxiliary t e s t . The AUX TEST key and AUX TEST binding post on the t u r r e t panel, provide f o r making voltmeter, dial speed, talking and ringing t e s t s a t the t u r r e t . Telephones and other apparatus may be tested, when brought to the t u r r e t location. 2.2.6 Dial t e s t facilities. The test t u r r e t provides m e a n s f o r measuring dial pulse speed and percent make. 2.2.7 Testing of r i n g e r s . F i v e push-key switches a r e compactly mounted on one key escutcheon, for selecting the d e s i r e d ringing frequency to be applied to the line for signaling. 2 -3 Optional test equipment 2.3.1 Howler. The howler provides a n effective m e a n s for attracting the attention of a s u b s c r i b e r , to a handset which was not returned to i t s c r a d l e . 2.3.2 SATT. When Strowger Automatic Toll Ticketing dials a r e used, a spotter pulse t e s t p e r m i t s checking party identifying features. 2.4 A l a r m s Night a l a r m . The night a l a r m is an audible signal provided with the test t u r r e t , that sounds when any of i t s l a m p s a r e lighted. 2.4.1 2.4.2 F u s e a l a r m . The fuse a l a r m provides supervision over the battery power supply. I 2.5 Keys. All t e s t circuits a r e key ended. Keys a r e assembled to flush-mounted escutcheons, located on the t u r r e t ' s panel. Each key is individually mounted, providing f o r i t s e a s y removal f r o m the front of the t u r r e t when desired. F o r key positions on the t e s t t u r r e t s e e figure 4. N 0 T E : Key escutcheon identifications a r e purposely capitalized in the text discussions, a s they appear on the t u r r e t panel. These i t e m s a r e treated in the o r d e r they appear on the panel, starting f r o m top to bottom, and left to right. 2.5.1 TEST 1 and TEST 2. Supervisory lamps a r e associated with trunks to the manual switchboard. Such trunks a r e shown on the key panel designation s t r i p a s TEST CORDS, and marked TEST 1 and TEST 2 on the key escutcheon above the respective keys. The lighting of one of these supervisory lamps indicates that i t s cord is plugged into the jack of either a line, o r a trunk a t the switchboard. This lamp is extinguished when the c o r r e sponding test key is operated to connect the test circuit to the trunk. When the test attendant r e l e a s e s the connection f i r s t , the lamp relights, until the test c o r d is taken down by the switchboard operator. 2.5.2 TALK & TEST. When the TALK & TEST key is operated in response to a lighted trunk and a n s w e r lamp, i t connects a n inspect o r ' s trunk f r o m a s e l e c t o r level, to the key panel for making t e s t s . 2.5.3 HOWL. The operation of the HOWL key connects the t e s t circuit to the "howler". The howler is not p a r t of the t u r r e t ; it is furnished only whenordered separately. A tone produced by the howler a t t r a c t s the attention of a s u b s c r i b e r to a handset which was not returned to i t s cradle switch. 2.5.4 AUX TEST. Binding posts located on the upper left c o r n e r of the t u r r e t panel, marked AUX TEST, +, -, and G (ground), provide convenient terminals for connecting external equipment to the testing t u r r e t , such a s a n o h m m e t e r , transmission measuring s e t , Wheatstone bridge, etc. Whatever is connected to these binding posts, is connected in the testing circuit, when the AUX TEST (auxiliary t e s t ) key is operated. 2.5.5 IN. When the IN key is operated, i t divides the line under t e s t by separating the IN and OUT l e a d s . The outside line is disconnected and the inside (switchboard end) circuit is extended to the key panel for the performance of t e s t s . 2.5.6 OUT. When the OUT key is operated, i t divides the line under t e s t by separating the IN and OUT leads. The inside ( o r switchboard) end of the circuit is disconnected and shorted, and the outside line is extended to the key panel f o r the performance of tests. 2.5.7 HC o r RLS CONN. When testing lines a r e plugged up a t the M.D.F., the operation of the HC o r RLS CONN*(heat coil o r r e l e a s e connector) key extends the heat coils to the key panel f o r the performance of t e s t s for open heat c o i l s . When groups of s u b s c r i b e r ' s lines a r e tested via the t e s t distributor and t e s t connectors, the operation of this HC o r RLS CONN key r e l e a s e s a t e s t connector f r o m one level of bank t e r m i n a l s , to p e r m i t the selection of another level which is under control of the t e s t attendant's dial. 2.5.8 HOLD. When the HOLD key is operated, i t enables the test attendant to hold a line that is connected to the t e s t t u r r e t for-testing. The attendant is then f r e e to perform other duties, o r make t e s t s on other lines. This feature is desirable whenever time is required for a n inspector to make other line t e s t s o r adjustments, until the held line is again ready to be tested a t the t u r r e t . The inspector at a s u b s c r i b e r ' s station can flash the station attendant without losing the connection, when the HOLD key is operated. 2.5.9 VM. The voltmeter is normally without battery. Operation of the VM (voltmeter) key connects the m e t e r , a c r o s s the + and terminals. 2.5.10 REV. The REV key is u s e d f o r r e v e r s ing polarity ( + and -) of the connections f r o m either line o r trunk under test, to the key panel. T h i s key is used when making voltmeter t e s t s for foreign voltage on the Tip ( o r +) side of the line, capacitance a c r o s s the line, divided ringing, o r testing for ground. 2.5 .ll BAT TEST. The operation of the BAT TEST (battery t e s t ) key p e r m i t s the operator to check the battery voltage. 2.5.12 VM SHUNT. The operation of the VM SHUNT (voltmeter shunt) places a shunt a c r o s s the voltmeter. The tables on pages 17 and 18 provide r e s i s t a n c e values for the corresponding valtmeter deflections. TABLE I provides r e s i s t a n c e values for m e t e r needle deflections, without a n external voltmeter shunt. TABLE I1 provides r e s i s t a n c e values with the shunt connected a c r o s s the voltmeter. 2.5.1 3 GRD. The operation of the GRD (ground) key, grounds the voltmeter testing circuit when checking faults. 2.5.14 DST. The DST (dial speed test) key is operated when testing dial speeds o v e r lines under t e s t . 2.5.15 TRANS BAT. When the TRANS BAT (transmission battery) key is operated, t r a n s mission battery is furnished to the telephone of a n inspector, installer, o r s u b s c r i b e r outside the exchange on connections which do not g e t battery f r o m a switch train. 2.5.16 TALK. When the TALK key is operated, voice transmission battery is furnished to the t e s t circuit telephone, and connects i t through a capacitance bridge to the outside line o r trunk. When both the TALK key and the MON key a r e operated, the t e s t attendant may monitor the line. 2,5.17 RING. When the RING key is operated, ringing c u r r e n t is connected to a line o r trunk, permitting the test attendant to signal a s u b s c r i b e r , r e c a l l an inspector, installer, etc . 2.5.18 MON. The operation of the MON key allows the test attendant to monitor a line under test, to verify whether the line is busy o r idle, check s u b s c r i b e r dialing, and the qualityof transmission, etc. When this MON key i s used in conjunction with the TALK key, the transmission battery for the attendant's telephone is disconnected during monitoring, to keep the background noise a t a minimum. relights and will remain lighted until the t e s t cord is removed by the switchboard operator. 2.5.19 LINE SW. The operation of the LINE SW (line switch) key connects the t e s t attenda n t ' s telephone to the assigned line either for answering c a l l s f r o m the t e s t position, or for originating outgoing c a l l s f r o m the t e s t position through the r e g u l a r exchange switch train. The LINE SW key r e m a i n s normal during t e s t s on lines and trunks. 2.6.2 Selector level trunk. A white s u p e r visory lamp is associated with the inspector's trunk f r o m a selector level, m a r k e d SEL LEV TRK on the designation s t r i p . This answering lamp indicates to the t e s t attendant that a c a l l h a s been made over this trunk. The lamp will flash on a r e c a l l signal to the test attendant and is under the control of the cradle switch a t the calling station (TALK & TEST key r e s t o r e d ) . 2.5.20 DIAL. When the DIAL key is operated (OUT key a l s o operated) i t will connect a trunk to the test distributor through to the t e s t telephone. 2.5.21 BCO. The operation of the BCO (bridge cut-off) key p e r m i t s testing the operation of the line relay. With the BCO and TALK keys operated, the t e s t attendant's telephone is connected to the line f o r dialing into the exchange. 2.5.22 NA. The NA (night a l a r m ) turn-key is used to p r e p a r e an audible signal whenever a s u p e r v i s o r y lamp is not visible to the test attendant. 2.5.23 RLS. The RLS ( r e l e a s e ) key has no application with o r d i n a r y dialing. This key is only used with SATT dials. This key has i t s momentary u s e in party identity t e s t s . 2.5.24 SET FULL SCALE. Before using the m i l l i a m m e t e r s c a l e for speed and r a t i o t e s t s , the m e t e r s c a l e should be s e t for full scale reading by operating the non-locking key m a r k e d SET FULL SCALE, and adjusting the rheostat designated SET FULL SCALE. 2.5.25 PULSE TEST. The PULSE TEST key is operated while making pulse ratio t e s t s . The pulse is not the pulse r a t i o of the dial itself, but only a s i t is repeated over the telephone line. 2.5.26 SPOTTER PULSE. T h e SPOTTER PULSE key is provided when SATT dials a r e used. This key is then operated, when making dial speed and party identity t e s t s . 2.6 L a m p s 2.6.1 T e s t cord. A white supervisory lamp is associated with each of two trunks to the manual switchboard, designated TEST CORDS on the t u r r e t panel. The lighting of one of t h e s e l a m p s indicates that the plug of an associated t e s t cord is plugged into the jack of a line o r trunk a t the switchboard. The l a m p r e s t o r e s when the t e s t attendant operates the associated TEST key, to connect the c i r c u i t to that trunk. When the test connection is r e l e a s e d by the t e s t attendant, the lamp 2.6.3 T e s t switch train. A white supervisory lamp is common to the two o r m o r e trunks to the t e s t switch train. The l a m p lights when a busy t e s t connector o r a busy called line is found on a n outgoing call, established by dialing through a test distributor, o r when a busy line is encountered during routine testing of a l l lines of a test connector. 2.6.4 Hold. A green lamp is provided f o r each trunk to the M.D.F. o r t e s t switch train, designated TRKS. TO TEST DIST. on the key panel. When the test attendant o p e r a t e s the HOLD key of a test trunk, the associated "hold" lamp lights. This lamp a l s o flashes on a r e c a l l to the test attendant under control of the telephone's cradle switch. 2.6.5 Busy lamp. A r e d lamp is provided f o r each trunk to the test switch train, when the t e s t distributors o r test connectors a r e multipled to other test positions. The lamp lights a t a l l multipled positions, when the trunk to the t e s t switch is busy. 2.6.6 Office fuse. A r e d fuse lamp lights when the office fuse blows. 2.6.7 SATT lamps. Numbered l a m p caps f o r checking the party identifying feature of SATT dials, a r e t r e a t e d in S4.9.3. 3. PROCEDURE OF OPERATION 3.1 Regular line equipment 3.1.1 Incoming (terminating call). When the t e s t circuit number is dialed the extension r i n g e r rings. The testman o p e r a t e s the LINE SW key and removes the handset of the test telephone. Conversation may now take place. To release the connection _ r e s t o r e the LINE SW key and replace the handset. 3.1 -2 Outgoing (originating). To make an outgoing call remove the handset and operate the LINE S W key. When dial tone is heard, proceed dialing a s with a normal call. To r e l e a s e the connection, r e s t o r e the LINE SW key and replace the handset. DST A7 Figure 5. Dial speed test. 3 -2 Inspector's trunk 3.2.1 Incoming call (terminating). NOTE: It i s impossible to call out. When the t e s t number h a s been dialed a white supervisory l a m p will light over the proper TALK & TEST key. Operate this key, the TRANS BAT key and the TALK key. Remove the handset and conversation m a y now take place. 3.2.2 Re-ring (ringer test). Do not perform r e - r i n g until the other party h a s hung up. Operate the RING key periodically. Ringing c u r r e n t is on the line a t a l l t i m e s when the RING key is operated, making i t n e c e s s a r y f o r the attendant to listen for the called party's answering during the silent period. 3.2.2 -1 Frequency ringing (bridged 5 pty). Operate the proper ring push button designated 1 , 2 , 3, 4, o r 5 under GEN on the t u r r e t panel and then operate the RING key periodically. Listen for the called party to answer. 3.2.2.5 Superimposed ringing (bridged 1 & 2 pty). Operate the proper ring push button designated 1, 2 , 3, 4 , o r 5 under GEN on the t u r r e t panel and then operate the RING key. Reoperate the TALK & TEST key. 3.2.2.6 Superimposed ringing ( 4 pty divided). Differing f r o m $3.2.2.5 in that the REV key m a y have to be operated to obtain the proper side of the line. 3.2.3 Dial t e s t s 3.2.3.1 Dial speed t e s t . Refer to figure 5 . Adjust the dial test s e t . Operate the SET FULL SCALE key and adjust the SET F U L L SCALE rheostat. Restore the S E T FULL SCALE key and operate the DST key. It is now possible to give instruction to the testman f o r dialing. Read the milliammeter and give the testman the r e s u l t s . Repeat the t e s t a s necessary. BAT TEST - I - 3.2.2 -2 Frequency ringing (bridged 10 pty, 1 & 2 ring). Differing f r o m S3.2.2.1 in that the RING key may have to be manually operated to s e c u r e the proper code. 3 -2.2 -3 Frequency ringing (divided). As in normal frequency ringing except R E V key may have to be operated to s e c u r e the proper side of the line. 3 -2.2 - 4 Code ringing. Operate and r e s t o r e the RING key manually, thus obtaining the proper code. Figure 6. Exchange battery test. V M SHUNT I VM I TRANS BfT TALK I DST I I I I I I I I I -I I I q; RllN G REV I I I I I I I I - -I - -- -I - - 1 I I I I I I I I 1 I I -I - -1- u TO T E S T LEADS Figure 7. Test of loop resistance. I 3.4.1 Checking polarity on line o r trunk. Refer to figure 6. Measure the b a t t e r y voltage by operating the BAT TEST key and reading the m e t e r . Note the voltage and r e s t o r e the BAT TEST key. 3.2.3.2 Pulse r a t i o t e s t . The t u r r e t i s s e t by the testman the s a m e a s for speed test except the PULSE TEST key is operated. NOTE: This is a line condition test. If the dial is out of adjustment, replace it. To test the dial bring it to the test t u r r e t and use the auxiliary t e s t circuit (connect to AUX TEST binding posts). 3.4.2 Checking loop r e s i s t a n c e . Refer to figure 7. Operate the OUT key and the VM key. Note the voltage on the m e t e r and find approximate resistance f r o m table in r e a r . If l e s s than 45,000, operate the VM SHUNT key and r e a d the m e t e r , noting the voltage. Find the r e s i s t a n c e f r o m TABLE 11. If the battery voltage does not appear in the table, r e s i s t a n c e may be calculated f r o m the following formula: X = R (E - V) / V; where X is the r e s i s t a n c e of the loop, E equals the t e s t b a t t e r y voltage, R equals the internal r e s i s t a n c e of the voltm e t e r (100,000R) and V is the voltmeter reading. With the VM SHUNT key operated, the value of R will be 1000R. . 3 . 3 . T e s t distributor. Check the white busy lamp, if this is not lighted, proceed. Operate the OUT key and operate the DIAL key. Remove the handset and dial the number of the line to be tested. R e s t o r e the DIAL key. If the called line is busy the SUPY lamp will light. Operate the MON key to monitor o r operate the TALK key if operator wishes to talk to the testman. 3.4 Voltmeter tests. Make connection to the p r o p e r line to be tested and operate the OUT key. Read the m e t e r o r if the needle is deflected below z e r o operate the REV key to r e v e r s e the polarity, allowing a m e t e r reading. BAT TEST 3.4.3 T e s t for ground. R e f e r to figure 8. Operate the OUT key and the VM key. Then TRANS T I I I RlrG I HOWL I RFV I I I 7-:-1 I I I I I I I I I I I I I I r - : - Y L l 1r I TO TEST LEADS Figure 8. Test for ground (negative side of line). BAT TE s T TA,LK TRANS BAT GRD RlpG I I I I I I VM I HOWL RFV I I I I I I I I I I I I - -I I I 3R 2Rl IR I I - -- I I -I- - - + u T O TEST LEADSs Figure 9. Test for open line. o p e r a t e the GRD key and o b s e r v e the m e t e r f o r deflection. To t e s t positive s i d e f o r ground, o p e r a t e the REV key. 3.4.4 T e s t f o r open (using r i n g e r capacitance). R e f e r to figure 9. O p e r a t e the OUT key and the VM key. O p e r a t e the REV key a n d o b s e r v e the m e t e r deflection. R e s t o r e the REV key and if the line is not open t h e r e should be a m e t e r deflection. 3.4.5 T e s t f o r foreign potential. R e f e r to f i g u r e 10. T o t e s t on the negative s i d e of the l i n e o p e r a t e the OUT key and the GRD key and o b s e r v e the m e t e r deflection. T o t e s t on the positive side of the line o p e r a t e the OUT key, the GRD key, and the REV key. T h e v o l t m e t e r reading shows the p r e s e n c e of a f o r e i g n potential. 3.5 Testing line circuit over test lines 3.5.1 Through t e s t d i s t r i b u t o r . Dial the line to be t e s t e d through the t e s t switch t r a i n . O p e r a t e the BCO key and the TALK key. Dial tone should be h e a r d . 3 -5.2 Through M.D .F. t r u n k s (jackbox). T h e OUT key is r e s t o r e d . Operate the IN, TALK, and BCO keys. Dial as on a n o r m a l c a l l . To r e l e a s e , r e s t o r e the TALK key. 3.5.3 Monitoring while the s u b s c r i b e r d i a l s 3.5.3.1 T e s t d i s t r i b u t o r . Seize the t e s t s w i t c h t r a i n . O p e r a t e the TALK and TRANS BAT keys. Ring and i n s t r u c t the s u b s c r i b e r . J u s t b e f o r e the s u b s c r i b e r dials, r e s t o r e the TRANS BAT key to prevent i n t e r f e r e n c e with dialing and operate a n d then r e s t o r e BCO key. T h e s u b s c r i b e r will dial. 3.5.3.2 M.D.F. O p e r a t e the OUT key, the TALK key, and the TRANS BAT key in that o r d e r . After i n s t r u c t i o n s a r e given to the s u b s c r i b e r , r e s t o r e the OUT a n d TRANS BAT k e y s and o p e r a t e the HC o r RLS CONN key. T o r e l e a s e , r e s t o r e the HC o r RLS CONN key. 3.5.4 T e s t of heat c o i l s . To t e s t the h e a t coils o p e r a t e the HC o r RLS CONN key and the BCO key. Upon operating the TALK key Figure 10. Test for negative foreign potential (negative side of line). d i a l tone should be h e a r d . If dial tone is not h e a r d the heat c o i l s a r e open. 3.5.5 Line t e s t of a t e s t connector. When a l l the l i n e s of a t e s t connector a r e to be tested, the o p e r a t o r d i a l s the connector. Dialing 11 and then making h i s t e s t s on 11, then dialing 1 and making t e s t s on 1 2 . Continue until through testing a l l l i n e s on t h i s level. When t e s t s on one l e v e l have been completed, o p e r a t e the HC o r RLS CONN key and then r e s t o r e it. Dial 21 and t e s t all l i n e s on this level and SO on. 3 -5.6 P e r m a n e n t line r e l e a s e . Operate the OUT and DIAL keys, dial the d i r e c t o r y number of the s u b s c r i b e r and monitor the line, If line is busy but is not being used, r e s t o r e the DIAL key. O p e r a t e the BCO key. If supy l a m p 1 19 i s not r e s t o r e d , the permanent line r e l e a s e c i r c u i t is not a b l e to shunt down the operated r e l a y and the equipment will have to b e r e l e a s e d manually. f o r performing SATT identity t e s t s ; however, to actually p e r f o r m the t e s t s , a u x i l i a r y t e s t c i r c u i t s a r e needed. F o r d e t a i l s on 5 spotter identification, s e e Automatic E l e c t r i c drawing H-85295 and c i r c u i t explanation E-85295 o r figure 13 of H-85275 with r e l a t e d explanation. 3 " 6 "4 Loop compensator adjustment. The following t e s t is for those telephones that a r e equipped with a variable loop compensator. The t e s t m a n will place h i s c a l l on the inspect o r ' s trunk to the t e s t attendant. Supy lamp I 3 will light. The t e s t attendant will o p e r a t e the TALK & TEST, TRANS BAT, and TALKkeys. Conversation m a y now take place. If the t e s t m a n r e q u e s t s a line voltage m e a s u r e ment, the t e s t attendant will connect the v o l t m e t e r a c r o s s the loop that is held up by r e l a y A3 in the i n s p e c t o r ' s trunk circuit. If the voltmeter needle is not deflected, the polarity is r e v e r s e d to it. The REV key will have t'o be operated. 3.6 Miscellaneous t e s t s 3.6.1 Howler. F i r s t o p e r a t e the OUT key, then o p e r a t e the MON key to d e t e r m i n e whether anyone is on the line. O p e r a t e the HOWL key to s i g n a l the s u b s c r i b e r to r e p l a c e the handset. 3.6.2 Postpay paystations. The c a l l will b e r e c e i v e d f r o m the t e s t m a n a t the paystation o v e r the i n s p e c t o r ' s trunk, Conversation t a k e s place. O p e r a t e the REV key to r e v e r s e polarity and c a u s e t r a n s m i s s i o n block a t the paystation. ( F o r f u r t h e r d e t a i l s on testing paystations, s e e Automatic E l e c t r i c Company's technical bulletin 702-82 o r 702-86.) 3.6.3 Auxiliary s p o t t e r dial test. The t u r r e t is equipped with p a r t of the equipment needed Read the voltage and r e c a l l the t e s t m a n and inform him of the r e s u l t s . If the testman r e q u e s t s a line r e s i s t a n c e reading, the connection to the loop is the s a m e . The OUT key is operated and the BAT TEST key is operated to find the exchange battery voltage. The VM SHUNT key i s o p e r a t e d and the BAT TEST key is r e s t o r e d . Note the voltage and find the r e s i s t a n c e f r o m the table. If the r e s i s t a n c e is not l i s t e d in the table, u s e the formula of S3.4.2. NOTE: F o r m o r e information on adjusting loop compensator, s e e Automatic E l e c t r i c Company's installation handbooks on the type 80 s e r i e s telephone. Figure 11. Block diagram of type 21 circuit arrangements. i 4. EXPLANATION O F OPERATION 4.1 General. The block diagram (figure 11) shows the test t u r r e t divided into four sections. The section labled "Testing facilities" is the section of the circuitry that s e t s up various conditions for the t e s t that is to be performed and shows the r e s u l t s of the tests to the test attendant. The "Test circuit" section, through the use of the keys associated with it, w i l l enable the test attendant to control the condition of the test leads entering the testing facilities and also enable the testing facilities to reach outside equipment. Regular line equipment has a c c e s s to the test circuit making it possible for the test attendant to receive and make calls as a regular subscriber. The "Equipment access" section, by the operation of the keys shown associated with each trunk, will both seize the outside equipment and connect the line o r trunk to be tested through to the test circuit. All trunks a r e on a common lead to the test circuit, enabling each to have a c c e s s not only to the t e s t circuit but also to the auxiliary test circuit. The "Outside equipment" section will complete the actual connection to the line o r trunk to be tested. Figure 14 is a schematic drawing of the type 21 t e s t t u r r e t and is a reference for the following sections. - 4.2 Trunk to M.D.F. (jackbox). The + and OUT, + and IN, and + and - HC leads connect to multiple jackboxes a t the M.D.F. A s i x conductor cord with a plug on one end and a jack on the other will connect the jackbox with the desired line. The test shoe will be inserted into the protectors of the line (figure 3 ) . This will remove the direct connection from the + and - lines through the heat coils and place i t on the + and - lines on the "in" side of the protectors. The + and - HC leads will go directly through the heat coils. Withbut any keys operated the + and - IN leads will form a loop from the inside of the protectors to the trupk to the M.D.F. circuit and out the + and OUT leads to r e t u r n to the M.D.F. Inversely the + and - OUT leads will come f f o m the "out" side of the protectors backto the circuit and out the + and - IN leads to return to the M.D.F. - 4.2.1 Testing inside plant through a jackbox. The test shoe is placed in the desired line. The BCO key and TALK key a r e operated. The IN key is then operated and a t make contacts 2R & 3R, and 2L & 3L will connect leads through make contacts of the + and the TALK key, the make contacts of the BCO key, to the test telephone. When the test handset is removed the loop will be complete and will seize the regular line equipment associated with the subscriber's line. Dial tone should be heard. To release the line equipment, the IN key is restored, breaking the loop to the test telephone. The BCO key and TALK key a r e restored. - 4.2.2 Testing the subscriber's line. The OUT key is operated, closing the + and OUT lines to leads + and -. The + and - leads a r e extended to the test circuits via the contacts of the HOWL, REV, and RING keys. The following t e s t s may be performed: the test for grounded lines (§4.7.4), the test for an open line o r open ringer capacitor (§4.7.5), the t e s t for foreign potential on the + and lines ($4.7.6). These t e s t s a r e described in the sections noted. - - 4.2.3 Monitoring while a subscriber dials. In o r d e r to gain the attention of the subscriber, ringing current i s applied to the subscriber's line over the + and - OUT leads. The OUT key is still operated. The RING key is operated and connects the + and - lines through to the ringing circuit where the R (-) lead will pass through a buzzer and b r e a k contacts of the frequency push buttons 1 through 5 and go to the generator. When the ringing loop is complete the buzzer will sound. When the subscriber answers the RING key is restored. To monitor while a subscriber dials, the OUT key, TALK key, and TRANS BAT key a r e operated. The OUT key, a t contacts 2L & 3L, and 2R & 3R will connect the + and lines through the TALK key make contacts, through the capacitors C4 and C5 to the test telephone. The line equipment will also be seized by closing a shorting loop a c r o s s the + and IN leads through contacts 8L & 9L of the OUT key. Transmission battery will be connected to the s u b s c r i b e r ' s line by the TRANS BAT key and extended through the break contacts of the DST, RING, REV, and HOWL keys, and the make contacts of the OUT key to the subs c r i b e r ' s telephone. The t e s t attendant may now give instructions to the subscriber. - - At this point several t e s t s relating to the subscriber's station can be made: Battery voltage test (§4.7.2), Dial speed test (§4.8.1), and Pulse ratio test (S4.8.2). These routine t e s t s a r e described in the denoted sections. Restoring the TRANS BAT key and the OUT key connects the subscriber to the already seized line equipment and allows him to dial the number which the test attendant desired. By leaving the TALK key operated and operating the HC o r RLS CONN key the test telephone will be connected through capacitors C4 and C5, over the + and - HC leads, through the heat coils, to the subscriber's line. This allows the test attendant to monitor the call. To remove his test telephone from the line, the test attendant r e s t o r e s the TALK key and the HC o r RLS CONN key. 4.2.4 Testing heat coils. The HC o r RLS CONN, BCO, and TALK keys a r e operated. The HC o r RLS CONN key will close a loop consisting of the + and - leads through make contacts of the TALK key and the BCO key to the test telephone. If the heat coils a r e not open the loop will seize regular line equipment through the heat coils and r e t u r n dial tone. 4.2.5 Release. To r e l e a s e the connection from the jackbox, the s i x conductor patching cord is removed f r o m the line a t the M.D.F. 4.2.6 Hold. To hold a connection (in figure 12, the s u b s c r i b e r ' s loop holds the connection) through a jackbox a l l keys will be restored and the OUT and IN leads will complete a loop from the M.D.F. to the test t u r r e t to hold the connection. The switch train may be held by the t e s t attendant by operating the leads HOLD key. This shorts the + and which completes the loop to the switch train. - 4.3 Trunk to t e s t distributor 4.3.1 Outgoing call. The OUT key is operated. The OUT key operated will complete a loop consisting of the + and - OPER leads passing through the #1 winding of relay B1 and break contacts of the DIAL key to seize the test distributor. The OUT key will also place ground to the #2 winding of relay B1. Relay B1 will not operate because of opposing - TRUNK T O MDE I JACK -BOX- magnetic fields from i t s #1 and #2 windings. Operation of the DIAL key will extend the loop to the test telephone and place battery to the + OPER lead. If the test distributor is busy, the supy lamp I 6 will be lighted from the grounded lead C . The test distributor is associated with the test connectors to which the exchange telephones a r e connected. If the test connector dialed i s busy, lead C will be grounded to the test distributor wiper causing the r e