4-WIRE LOCAL LOOP DIGITAL DATA SYSTEM PAGE 1. GENERAL (a) (b) NOTICE. Not for use or disclosure outside the

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1 BELL SYSTEM PRACTCES AT&TCo Standard SECTON ssue 4, October WRE LOCAL LOOP MANTENANCE PROCEDURES DGTAL DATA SYSTEM CONTENTS PAGE CONTENTS PAGE 1. GENERAL TROUBLE REPORTNG AND SOLATON.. 3. TROUBLE ANALYSS PROCEDURES Trouble Clearng Procedure for Type F Loop Secton Trouble Clearng Procedure for Type G Loop Secton LOCAL LOOP WTHOUT 56-KB/S DGTAL RE- PEATER(S) Trouble Clearng Procedure for Type H Loop Secton LOCAL LOOP CONTANNG 56-KB/S DGTAL S GENERAL 4. REFERENCES Fgures Trouble Clearng Procedures for Local Loop Wthout Repeater(s) Types of Local Loops contanng Dgtal 56- kb/s Repeater(s) Trouble Clearng Procedure for Local Loop Contanng 56-kb/s Dgtal Repeater(s). Trouble Clearng Procedure for Type A Loop Secton Trouble Clearng Procedure for Type B Loop Secton Trouble Clearng Procedure for Type C Loop Secton Trouble Clearng Procedure for Type D Loop Secton Trouble Clearng Procedure for Type E Loop Secton TCE 1.01 $Ths secton descrbes mantenance procedures used to locate trouble on a Dgtal Data System (DDS) 4-wre local loop. These procedures refer to tests that are documented n Sectons , , , and dependng on whch test equpment s used.~ 1.02 (a) (b) Not for use or dsclosure outsde the Ths secton s ressued for the followng reasons: To nclude nformaton on SLC*-96 Carrer System when usng dataport channel unts To nclude nformaton on the 500B Data Servce Unt (c) To nclude nformaton on Lne Access Test System (LATS), Bt Access Test System (BATS), Automated Bt Access Test System (ABATS), and Swtched Mantenance Access System/Swtched Access Remote Test System (SMAS/SARTS) (d) To change Servng Test Center (STC) to Centralzed Test Center (CTC). Revson arrows are used to emphasze the more sgnfcant changes. *Trademark of Western Electrc Bell System except under wrtten agreement Prnted n U.S.A Page 1

2 k SECTON A DDS local loop conssts of the followng: (a) A 500A-type data servce unt (DSU), or a 550A-type channel servce unt (CSU) located on customer premses (b) A connectng 4-wre local loop (c) An offce channel unt (OCU) or OCU dataport channel unt (OCU DP) located n the servng central offce (SCO) (d) A maxmum of two 56-kb/s repeaters where 56-kb/s servce s provded The 4-wre local loop conssts of cable to a SCO where DDS multplexng equpment s located. n some cases the cable may be routed through a baseband offce. Nonloaded cable pars must be used and are the same as those used for any of the common servces such as message telephone, and short-haul carrer systems (a) (b) (c) A DDS local loop trouble s ndcated by: A satsfactory OCU loopback test and a faled channel loopback test A satsfactory OCU and channel loopback test and a faled DSU oopback test ntermttent error performance on channel and/or DSU loopback test $Trouble analyss procedures and nformaton n ths secton are based on the results of the one-employee and/or two-employee tests. The test results should be recorded as a benchmark value on a local loop record card E Warnng: A dc loop current n excess of 250 ma may damage the DSU/CSU at the staton end when makng ether the oneemployee or two-employee test. Do not use test equpment, for example, a breakdown test set, that apples a current greater than 250 ma to the cable pars, unless the OCU or OCU DP has been unplugged and the DSU/ CSU has been dsconnected from the pars. Ths warnng apples to paragraphs 1.08 and The one-employee tests are prmarly for mantenance and trouble clearng but may also be used for nstallaton testng, f requested. The one-employee tests may be made at the OCU bay, OCU DP, local test desk (LTD), LATS test panel, SMAS/SARTS, BATS, or ABATS The two-employee tests are prmarly for nstallaton tests but may also be used for mantenance testng, f requested. The two-employee test s made between the staton and the OCU bay, OCU DP, LATS test panel, SMAS/SARTS, BATS, or ABATS.4 2. TROUBLE REPORTNG AND SOLATON 2.01 Routne mantenance s not requred for DDS local loops. Procedures for clearng trouble normally start by recept of a trouble report at a CTC. The CTC s the prmary pont of contact for the DDS customer. 2.o2 Transmsson faults on the local loop are not alarmed and wll normally be reported to the CTC by the customer. The customer may detect faults by lamp or nterface lead ndcatons on the DSU Routne mantenance s not requred for the dgtal 56-kb/s repeater. All crcut packs are nstalled on a plug-n bass. n the event of a repeater falure, the defectve crcut pack can be easls- replaced Two green lght emttng dodes (LEDs) on the central offce (CO) mounted repeater montor for the presence of data or dle code transmtted through the repeater n each drecton. The TRMT DA LED, when llumnated, ndcates the presence of data toward the staton DSU or CSU. The RCV DA LED, when llumnated, ndcates the presence of data towards the DDS network. The absence of data, due to faclty trouble or component falure, wll cause one or both of the LEDs to be off. A fuse falure wll cause an offce alarm and a red F ALM lamp s lghted Four jacks located on the CO mounted repeater shelf provde access for de and ac testng of the loop facltes from the repeater locaton. The repeater can also be bypassed by operatng a swtch located at the front of the repeater or removng smplex current n the newer (Lst 2) \ erson of the repeater. n the bypassed condton, testng of the entre loop (except the repeater) can be performed from the CO contanng the OCU. Note: The outsde plant (OP) repeater can be remotely bypassed to allow de tests to be per- Page 2

3 1SS 4, SECTON formed by removng the dc smplex current from the loop. Normal OP repeater operaton s restored by reapplyng de smplex current to the loop $After a touble report s referred from a CTC, a techncan must perform a foregn voltage test, an nsulaton resstance test, and a loop resstance test wthn 15 mnutes n order to meet the overall mantenance objectves for Dgtal Servce. These tests may be made by usng ABATS, BATS/LATS, SMASA3ARTS. They may also be made at the OCU or LTD of the SCO. The test results must be passed to the CTC so a dspatch to the customer staton can be determned and coordnated f requred. 3. TROUBLE ANALYSS PROCEDURES 3.o1 Ths part provdes the trouble analyss procedures for the DDS local loops wthout 56-kb/s dgtal repeaters and for loops wth repeaters. These loops are also referred to as nonrepeatered and repeatered wth each type requrng dfferent trouble clearng procedures. These procedures are followed wth the coordnaton of the responsble servng hub offce. These procedures begn after some loopback testng has already been made, such as an OCU oopback test that passed, but the DSU and the channel oopback tests faled. Loopback testng s possble from dfferent locatons wthn the DDS The oopback tests procedures are documented n dfferent sectons dependng on the test equpment or test system used. The recommended test system (ABATS) can only test loops that are connected to a hub offce va LATS. Refer to Secton for these remote test procedures. Manual test procedures usng BATS s documented n Secton Local loop test procedures for ntermedate and end offces may use SMAS/SARTS, local OCU or OCU DP, or LTD test procedures whch are contaned n Secton LOCAL LOOP WTHOUT 56-KB/S DGTAL (S) 3.03 Ths subpart provdes procedures that are used to solate and clear troubles on a DDS local loop that does not contan dgtal 56-kb/s repeater(s) (nonrepeatered loop). Fgure 1 shows the trouble clearng procedure for a nonrepeatered loop whch provdes subrate (2.4-, 4.8-, and 9.6-kb/s) servce and for short loop 56-kb/s servce. These procedures are made from the SCO.t LOCAL LOOP CONTANNG 56-KB/S DGTAL S 3.04 Ths subpart outlnes the analyss procedures that are used to solate and clear troubles on the DDS local loop contanng 56-kb/s dgtal repeater(s). Fgure 2 shows the varous loop arrangements that can be confgured for 56-kb/s ser~ ce and the varous types of loop sectons (A through H type) that may be nvolved. $The trouble should have already been solated by the channel loopback test to a specfc secton, e, between OCLT or OCU DP and a repeater, between two repeaters, or between the last repeater and the staton. Some of the solaton procedures requre tests between a CO or an OP repeater and the staton. Other procedures are requred between repeaters or between a smplex power unt and a repeater Trouble clearng procedures begn and are shown n Fg. 3 through 11 for a repeatered loop whch s at the 56-kb/s rate.~ 4. REFERENCES 4.01 The followng sectons can be referenced for addtonal nformaton on mantanng local loops: SECTON DESCRPTON 6F and 6FR Voceband Nose Measurng Sets, (J94006F and J94006FR), Descrpton, Operaton, and Mantenance Dgtal Data System, KS Data Test Set (Transmtter) Dgtal Data System, KS Data Test Set (Recever) 4-Wre Local Loop, Test Procedures, Dgtal Data System Bt Access Test System (BATS) and Lne Access Test System (LATS), Manual Test Procedures, Dgtal Data System Automated Bt Access Test System, Remote Test Procedures, Dgtal Data System Dgtal Data System, Offce Channel Unt, Descrpton Page 3

4 SECTON SECTON DESCRPTON SECTON DESCRPTON Dgtal Data System, Offce Channel Unt, Mantenance Dgtal Data System, Offce Channel Unt, Test Procedures Dgtal Data System, 56-kb/sRepeater, Descrpton Dgtal Data System, 56-kb/sRepeater, Test Procedures SLC -96 Subscrber Loop Carrer System, General Descrpton Dgtal Transmsson Systems, D3B Channel Bank, Dataport Operaton, Descrpton, nstallaton, Mantenance and Tests Dgtal Data System, 550A-Type Channel Servce L nt, Test Procedures Dgtal Data System, 500A-Type Data Servce Unt, Descrpton and Operaton Dgtal Data System, 500A-Type Data Servce Unt, Mantenance Dgtal Data System, Data Servce Unt 500A-Type, Test Procedures Locatng Cable Faults Wth the 96A Test Set 468F Apparatus Case, Descrpton and nstallaton.5% Dgtal Data System, 550A-Type Channel Servce Unt, Descrpton F Apparatus Case, Mantenance and Acceptance Testng Dgtal Data System, 550A-Type Channel Servce Unt, Mantenance Dgtal Data System, 950A Testboard (J70176A and B), Descrpton and Operaton Page 4

5 1SS 4, SECTON START NSULATON RESTEMCE, AND LOOP RESSTANCE GVEN N SECTON (TE 1). \ / otestng blth ABATS OR SNAS/SARTS NAKE OPEN LOOP CAPACTANCE TEST l- J *] 1 OP AND MAN DSTRBUTNGFRAME lcheck POWER FUSE AT BAY CLOCK, POWER, A ALARMS UNT A AT LOCAL TMNG SUPPLY l CORRECT OPTONS LDOPBACK TEST TEST ) T TFY CTC THAT LOCAL TROUBLE S CLEAREO NoTs: 1. These tests may not be requred f already made by ASATSor SMAS/SARTS.Obtan and record results. adspatch TECHNCAN TO STATON REPLACE CSU/OSU WTH SPARE HAVNG CORRECT OPTONS c1 MAKE CSU/OSU NSTALLATONPER SECTON OR Fg. l Trouble Clearng Procedures for Local Loop Wthout Repeater(s) (Sheet 1 of 2) Page 5

6 SECTON Q A --7=- DSPATCH TECHNCAN TO STATON J TFY CTC THAT LOCAL TROUBLE S CLEARED 4 DSCONNECT FROM LOCAL CSU/DSU LOOP MAKE TUO-EHPLOYEE FOREGN VDLTAGE, NSULATON RESSTANCE, AND LODP RESSTANCE TEST GVEN N SECTON (cj ] ND Q MAKE FUNCTONAL TEST PER SECTON OR L G B h * e & & Fg. l Trouble Clearng Procedures for Local Loop Wthout Repeater(s) (Sheet20f 2) Page 6

7 1SS 4, SECTON OCu Pm DSU / UNT Csu TE : A POWER UN T S A 56-Kb SHELF EQU PPEO W Tt 0NL% AN LA2 C RCU T PACK OCu DSU/ C.su ~.~ - ct l~! ; EC N OCu UNT P PuR UNT osu/ CSu L 1 L ~,::CCTON -, ~,,,,,,CTON OCu?uR UNT DSU/ Csu, ~:;:::EcTON~ ~ :=, ~ ~~~~~ECTON~, Ocu co DSU/ c Su Pg. 2 Types of lecal loops Cmtanng 56-kb/s Dgtal Repeater(s) Page 7

8 START P* REMOVE DEFECTVE MAKE OCU OR OCU OR OCU OP A MAKE OCU TEST Ocu OP REPLACE WTH ~ OR OCU OP LOOPBACK TEST CORRECTLY OPTONEO LPBK TEST SPARE 1MAKE LPBK TEST AT FRST (TE 1) mrepar SMPLEX MAKE LPBK TEST (TE 2) MAKE OCU VOLTAGE AND REPEAT TO SECOND SMPLEX VOLTAGE TEST LPBK TEST AT FRST, F TEST PER SECTON. CONTACT EQUPPEO (TE 1) NTS F TROUBLE REMANS J ATTEMPT LPBK TEST TEST MAKE CSU/OSU TEST AT FRST TO LPBK TEST VERFY TROUBLE S N 4 OCUOROCUOP A FRST 4 SECTON TEST CHECK POER FUSE A F TROUBLE REMANS, CONTACT NETWORK TECHNCAL SUPPORT (NTS) o (TE 2) SELECT TYPE OF LOOP USNGFG. 2 A LPBK TESTNG e SECTONALZATON RESULTS c1 TFY CTC OF TROUBLE FOU TES : 1. Lst 1 Type or early model repeaters may requre assstance at repeater locaton for loopback testng. 2. A ground or open wre close to a repeater can ndcate a good loopback for that loop secton and a bad loopback for the next loop secton. TEST TYPE A LOOP SECTON AS GVEN N FG. 4 TEST TYPE O SECTON AS GVEN N FG. 7 LOOP a@j? TEST TYPE E TEST TYPE F TEST TYPE G LOOP SECTON LOOP SECTON LOOP SECTON AS GVEN AS GVEN AS GVEN N FG. 8 N FG. 8 N FG. 10 TEST TYPE H LOOP SECTON AS GVEN N FG. 11 Fg. 3 Trouble Clearng Procedure for Local Loop Contanng 56-kb/s Dgtal Repeater(s)

9 1SS 4, SECTON b MAKE ONE-ERPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, A LOOP PLUS TERMNAL RESSTANCE ~ OP + FOREGN VOLTAGE, MULATONRE SSTANCE, A LOOP RESSTANCE BETWEEN OCU OR OCU OP AND LOOP SDE OF MDF CHECK POER AND REVERSALS THROUGH SMPLEX POUER UNT TEST DSPATCH TO OP REPAR SMPLEX REPLACE POWER UNT A REPEAT LPBK CP S TEST J J vrepar OR REPLACE OFFCE WRNG A TEST NEW MRNG A DSPATCH 1 TO OP MAKE TWO-EMPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, AND LDOP RESSTANCE BETUEEN MOF A OP DPERFORM TUO- EMPLOYEE OC A AC 7 REQUEST NW CABLE! REQUEST NEW CABLE PARS A TEST PARS A TEST NEW PARS NEH PARS Fg. 4 Trouble Clearng Procedure for Type A Loop Secton Page 9

10 SECTON MAKE ONE-EMPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, AND LOOP PLUS TERMNAL RESSTANCE t u DSU/CSU + REPLACE OSU/CSU DSPATCH AND TEST NEW TO STATON - UNT FOR DSPATCH TO STATON umake TWO- EF EMPLOYEE OC TEST FROM OCU OR OCU OP TO STATON -L, t v b REPLACE DK OSU/CSU AT STATON MAKE CONTNUTY TEST ON STATON MRNG CABLE PARS AND TEST NEW PARS. + REPAR STATON HRNGAND TEST FOR CONTNUTY OSPATCH TO DP - MAKE TUO-EMPLDYEE OC FROM OP TD STATDN \ ( )= l%pl F MAKE TWO-EMPLOYEE AC FROM OP RPTR TO STATON REPLACE CP S Em-Es-@ ( +% \ [ Fg. 5 Trouble Clearng Procedure for Type B Loop Secton Page 10

11 1SS 4, SECTON co MAKE ONE-EMPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, LOOP PLUS TERMNAL RESSTANCE ~ + OSPATCH TO CO REPLACE MAKE ALL RPTR OFFCE F e ~ LPBK UCCUPED CP S 1 PMAKE TUO-ERPLOYEE OC BETUEEN OCU OR OCU DP A LOOP SDE OF MOF AC TO OCU OR OCU DP REPAR OR REPLACE OFFCE WRNGAND TEST t NEUUR* + r MAKE TWO-EMPLOYEE DE BETUEEN DCUANDMOFOF CO RPTR REQUEST AO OF NTS REQUEST NEU CABLE PARS A TEST NEW PARS h 4 4 REQUEST MU CABLE PARS AND TEST 1 EU PARS --6 A F@6-TroubleCl earng Procedure for Type C Loop Secton Page 11

12 SECTON tlake ONE-EMPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, AND LOOP PLUS TERMNAL RESSTANCE co =-klosu csu -+ ( s )-t!? n SPATCH REPLACE DSU/CSU AT STATON AND TATON REPEAT LPBK TEST OSPATCH TO CO RPTR OFFCE F UCCUPED d F9= rnun JVU Un OCU DP TO STATON SDE OF LAST RDF tsls DSPA ----TCH STATON TO,= 1 DSPATCH TO CO RPTR OFFCE F UCCUPED CHECK POWER AND REVERSALS AT STATON SOE OF MOF REPAR OR Mawr Gb+Em rnnc TUO-EMPLOYEE REPLACE OFF FCE DC FROM WRNGA TEST CTAT( JN,, TO MOF NEUHRNG 11 OF L.AST OFFCE v TFY CTC THAT TROUBLE S CLEARED k)a me v nu REQUEST NEW CABLE PARS AND TEST NFU DATRC 23 REQUEST OF NTS AD. v REQUEST AD ~ OF NTS Fg. 7 Trouble Clearng Procedure for Type D Loop Secton Page 12

13 1SS 4, SECTON F 1ST OP NJLATON RESSTANCE, AND LOOP PLUS TERMNAL + :~LExt v MD,= 2ND OP!=2 DSPATCH TO SMPLEX POUER UNT N CO Y OC FROM OCU OR OCU OP TO STATON SDE OF SX PUR UNT. POWER UNT AT SX POHER UNT --J---l -F- REPAR SMPLEX!zz!E7 FO ER;,TA + REPEAT DSPATCH TO DC FROM MOF 2ND OP - OR SX PWR UNT TO DK 2ND OP RPTR ~ r- +!FENwloREPLACE T A T 2ND OP MAKE CONTNUTY TEST FROMMDF TO MD, LPBK A * TEST DSPATCH 1ST OP TO MAKE TWO-EMPLOYEE OC FROM 1ST REQUEST AO - OP RPTR TO SX OF N TS POWER UNT REPAR OR REQUEST NEW _ REPLACE OFFCE CABLE PARS AND blrnbof POUER TEST NEWPARS UNT Frg.8 Trouble Clearng Procedure for Type E Loop Secton (Sheet 1 of2) Page 13

14 SECTON DSPATCH 2ND OP TO J REPLACE RPTR CP S AND MAKE ALL LPBK FROM OCU OR Ocu OP J TFY CTC THAT TROUBLE S CLEARED d= AC A OC FROMSX POUER UNT TO 2N0 RPTR (+-P=- 1 \ / REQUEST NEU CABLE PARS AND 4+ TEST NEU PARS F AC AND OC FROM 1ST RPTR TD 2ND RPTR L + JND EEd Fg. 8 Trouble Clearng Procedure for Type E Loop Secton (Sheet TFY CTC THAT TROUBLE l S CLEARED 2 of 2) Page 14

15 1SS 4, SECTON MAKE ONE-EMPLOYEE FOREGN VOLTAGE, NSULATON RESSTANCE, AND LOOP PLUS TERNAL RESSTANCE DSPATCH TO CO RPTR OFFCE F UCCUPED 1 MAKE TUO-ERPLOYEE DC FROM OCU TO FKJF TOWARD OP RPTR 1 OF co OSPATCH TO CHECK POWER A CO RPTR OFFCE + REVERSALS THROUGH F PJOCCUPED 1ST CO RPTR 1 TEST REPAR CO 1 AND REPEAT LPBK OP b OSPATCH TO OP REPLACE CP S ALL LPBK FROM OCU -dmake -1 REPAR OR REPLACE OFFCE MRNGAND EEL OC FROMMDF OF RPTR TO OP RPTR ml REPLACE OP + w AC A DC FROM CO RPTR TO OP RPTR -& REQUEST NEW CABLE PARS A TEST NEW PARS Fg. 9-Trouble Clearng Procedure for Type FLoop Secton Page 15

16 $ nre%rl? R! z NSULATON RESSTANCE, AND LOOP PLUS TERMNAL L RESSTANCE ~ + OSPATCH TO CO RPTR OFFCE F + UCCUPED DSPATCH TO CO RPTR OFFCE F UCCUPED OSPATCH TO 0 8 HAKE TUO-EMPLOYEE OC FROM 0 RPTR TO MDF OF CO RPTR DC FROM OCU ~ OR OCU OP TO S10 OF LAST MOF fes 4 MAKE CONTNUTY TEST ON OFFCE WRNGFROMMDF TO R ( TEST )- --@ 1REPAR OR REPLACE OFFCE WRNG A TEST NEU URNG OF N S CHECK POWER AT CO FOR OP o- TEST L-J OSPATCH TO OP REPLACE T CP S AND PERFORM ALL LPBK FROM OCU OR OCU OP T, *, REPLACE CO MAKE ALL LPBK FROM OCU THAT TROUBLE z CP S OR OCU D S CLEAREO u x A MAKE TWO-EMPLOYEE OC FROM OCU e TO CO RPTR OSPATCH TO 0 MAKE TWO-EMPLOYEE AC FROM OP e RPTR TO CO RPTR L- REPLACE RPTR CP S AND PERFORM ALL LPBK FROM OCU CR OCU D REQUEST KU CABLE PARS AND TEST NEW PARS rm ~ 4REQUEST NEU CABLE TFY CTC THAT PARS A TEST TROUBLE S NEW PARS CLEAREO L J 1 Fg. 10 Trouble Cleorng Procedure for Type G Loop Secton EE@l

17 1SS 4, SECTON arake THO-EMPLOYEE MAKE ALL LPBK OC FROM OCU (TE 1) OR OCU OP + 4 REQUEST NEU CABLE FAULT PARS AND TEST FOUND NEU PARS TFY CTC THAT TROUBLE S CLEARED M REQUEST AO OF NTS CHECK POWER AND REVERSALS NTO 2ND CO TE: 1. The fault n the loop secton s probably between the repeaters. DSPATCH TO 1ST CO DFFCE F UCCUPED UCCUPED J DC AND AC FROM RPTR TO RPTR 4 7REPLACE CP S h REQUEST AD OF NTS f Fg. n-trouble Clearng Procedure for Type H Loop Secton Page Pages