|                                 |

                    |  The Cross Bar Switching Guide  |

                    |           [Xbar #5]             |


                    |         By Xbar Switchman       |

                    |  Courtesy of New York Telephone |

                    |     Operating Staff - Plant     |


                     Phile #9 of P/HUN Magazine Issue #5

  Special thanks to Lord Micro and Seeker who were the people behind the bins.



This guide was developed by the Plant Training Center,

to provide a ready reference of information that  can be used by The Central

Office Switchman during the performance of his daily work.   



In this part Class "A" reports are only covered. Future issues will have

MTF Tests/Class C/Alarms/Trouble Recorder etc.

Section #1 - Class "A" Reports        



CLASS "A" Reports


Class "A" troubles are those reported by subcribers. Prompt and complete

handling is very important. Propmtness because the subcribers service may be

affected and completeness so that the customers service is not impaired  a 

second time for the same reason. 

If the line is held out of service by euipment note the x-points closed and

release the line hold magnet to allow the subcribers service. If necessary a

channel plug may be inserted in the junctor switch portion of the linkage in

order to release the subcriber's line sooner. The remaining linkage will be 

help up. So therefore what is done in such problems is to actually trace 

this held path and analyze to determine why it was held up. To keep Class "A"

report to a minimum switchman analyze all trouble recorder cards as soon as

they come in and mark each card for missing or false punches and compare with

previous cards. In this way repeaters can be spotted quickly and acted upon.

Usually switchman activate the continuity and ground test circuit of the

markers at regular  intervals in order to pick up linkage tip and ring 

troubles. Using this approach, along with regular testing procedures should

keep common euipment troubles to a minimum.

Here is a list of Class "A" trouble reports:

NDT - No Dial Tone    

CC - Cant call

DCLR - Double Connection-Lift Receiver

PS - Permanent Signal

COO - Cutoff Outgoing

DCO - Double Connection Outgoing

CBDT - Cant Break Dial Tone

DTWD - Dial Tone While Dialing

DCWD - Double Connection While Dialing

NAR - No Audible Ring

GWN or INTC  - Gets Wrong Number of Intercept

ATB - All Trunks Busy

DA - Dont Answer

GB-FB - Gets Busy-False Busy

CH - Cant Hear

CBH Cant Be Heard

NSY - Noisy 

DTRWT - Dial Tone Returns While Talking

XT - Cross Talk

COL Clicks On Line

BDR - Cell Doesn't Ring

DGC - Dont Get Calls

RI - Reaches Intercept

FRI Fails  to Reach Intercept

CIE - Called in Error

FB - False Busy

BRCM - Bell Rings - Cant Meet 

DCI - Double Connection Incoming  

CT - Cant Trip Ringing

COI - Cut OFf Incoming

FDA - False Dont Answer

Here are the explanations of Class "A" troubles occurances:  



1) Open between HMDF and L.Lk. Frame.

2) Open L relay; Loose connection on L relay; open T or R connections on L.Lk.

   Frame; Open hold magnet.

3) Paritially Energized L relay or Hold Magnet.

4) Hold magnet help operated.

5) Dirty contacts or no follow on line hold off normal contacts.

6) Line switch and junction switch cross points .

7) If heavy reports from one frame check LLMC.

8) Review trouble cards for DT Marker Trouble.

9) Routine Originating Registers for dial tone.



1) Check for bent select fingers on L.SW & all J.SW's.

2) Check for false operation of 2 or more line hold magnets on Incoming and

   Outgoing calls.

3) Review trouble cards for  DT markers - especially "X" indicators

4) Review trouble cards on DT markers for LXP or JXP indicators.



1) Shorted T & R.

2) False ground on ring side.

3) If Linkage fails to release-trace and check for linkage or PSHT trouble.




1) Loose Connection on T, R  or S lead.

2) Poor make of L.Lk Cross Points.

3) Poor make  of hold magnets off normals

4) Review Completing Marker Trouble cards  for LXP type trouble o outgoig 


5) If heavy reports from 1 line link frame check LLC.

6) Possible Pretranslator or PRTC Trouble



1) Inspect for cross T & R.

2) Inspect for bent select fingers or 2 selectes operated.

3) Inspect for 2XPTS Closed on same horizontal.

4) Check Comp. MArker Touble Cards (for "X" indications)

5) Check Comp. Marker Trouble Cards (for LXP; JXP indications)

6) Possible doulbe wiring on trunks apperance on TLK frame.

7) False SL inidications.



1) Possible hihg resistance on subcribers line.

2) Routing Originating registers (DT Test). 




1) Loose sleeve connection.

2) LLK XPTS poor sleeve conection.

3) False release of O.R

4) Pretranslator.



1) Crossed T or R.

2) False selected bar operation.

3) Bent select finger.



1) Trunk pre-trip.

2) Stuck sender or register.

3) subcriber class of service wiring.

4) Out sender link X-Points.

5) Wrong TB-TG wiring of Outgoing Trunk.

6) Wrong  RN trunk X connection.

7) Wrong trunk options.

8) Trasverter-Transverter Connector.

9) Recorder.

At terminating end:

1) Ringing selection switch.

2) Incoming Trunk Wiring.

3) Linkage.



1) Loose tip and/ or ring.

2) Unbalanced subcriber line.

3) Marker Wiring and Number group wiring.

4) Originating register or outgoing sender trouble.

5) Wrong TB-TG-RN Trunk or TLK frame.

6) FAT frame wiring



1) Incoming register trouble.

2) Ringing selection switch trouble.

3) Wrong NG Wiring.

4) Incoming trunk R Relay adjustment.

5) Open T or R from Incoming trunk to called subscriber.

6) Outgoing trunk supervision trouble.



1) Might be overflow instead of busy.

2) Outgoing trunk trouble.

3) Wiring number group wiring.

4) Ringing selection switch trouble.

5) Incoming Trunk wiring

6) Troulbe release by Marker.



1) Subcriber's line has high resistance.

2) Swinging or poor wiring  connections-tip or ring.

3) Dirty X points (tip or ring).

4) Outgoing trunk-poor transmission.



1) Subscriber's line has high resistance.

2) Swinging or poor wiring connections tip or ring.

3) Dirty X points (tip or ring).

4) Poor transmissions on trunks.



1) Loose Connection tip or ring.

2) Dirty pins on 444 jack on VMDF.

3) Tip or Ring resistance cross.

4) Outgoing trunk transmission.

5) Induction on subcriber's line.

6) Dirty contacts in talking linkage.



1) False release of outgoing trunk or incoming trunk euipment.

2) Poor connection  or dirty contacts of sleeve lead of talking path.




1) Before dial tone

     a) Line link double connection.

     b) Induction on subcriber's line.

2) After dial tone

     a) Trunk cable induction.



1) Vibrating relay.

2) Riding selector.

3) Wiring interference.

4) Improper testing.

5) Loose connection in talking path.



1) Open T or R from incoming trunk to subcriber's line.

2) Grounded ring in linkage.

3) Defective incoming trunk.

4) Ringing selection switch trouble 

5) Incoming register trouble.

6) Wrong NG or ADF wiring.

7) Check trouble cards for CON and FCG failures on incoming calls.



1) Number group or ADF wiring.

2) Open sleeve in linkage.

3) Incoming register trouble.

4) Incoming trunk options or wiring.



1) Possible incoming X'd sleeve.

2) Possible LG relay cross.

3) Possible help up on incoming call.

4) Possible help up by operator.





1) Open Tip or Ring (T or R )     

2) Unbalanced line.

3) Crossed ring sides. 

4) Loose or open sleeve-possible 1 ring.

5) Incoming trunk trouble .



1) Crossed sleeves (2 hold magnets)

2) 2 select bars operating

3) 2 LG relays operating.




1) Defective incoming trunk.

2) Possible high resistance ring side.



1) Incoming trunk trouble (false release).

2) Loose or dirty contacts of sleeve of incoming connection.



1) Reaching wrong #'s possible- see GWN.

2) Ringing selection switch trouble.

3) Incoming trunk trouble.

4) Incoming linkage open T or R.

5) Called sub line open T or R.


End of PART 1


Well this article will conclude on future issues. Hopefully now you have a 

better understanding of all kinds of troubles reported to the Xbar office.

This article is a little complicated to follow and DOES require the basic 

understanding of No. 5 Crossbar Switching System. 

Would also like say thanks to Lord Micro and Seeker who were the people behind

the bins at a local office.