Understanding and Troubleshooting Twisted Pair

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Understanding and Troubleshooting Twisted Pair

• Ed Rousselot

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Agenda

• Introduction to Tempo
• History of Twisted Pair
• Inside Wiring Schemes
• Inside Wiring Problems, Causes, Effects
• Equipment Needed
• Stress Test
• Leakage Test
• Troubleshooting Techniques
• Questions Answers

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Presented By

• Ed Rousselot
• Field Technical Support
• The Americas
• 817-905-2666
• erousselot_at_greenlee.textron.com

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Tempo/Greenlee Locations
Newport, Wales Sales, Engr
Vista, CA Mfg, Mkt, Sales
Rockford, IL HQ
Remsheid, Ger Sales, Mktg
Mesa, AZ Mfg, Mkt, Sales
Oakville, ON Engr, Mfg
Ft Worth, TX Engr
Shanghai Sales
Bangalore, India Engr
Singapore Sales
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• So, you are getting into providing telephone
  service.
• Good Luck. You are going to need it because

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• The Playing Field Is Not Level!!!!!!
• Ed, whatever do you mean?

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Background

• Cable companies have been providing phone
  service for almost ten years with great
  success.
• Technicians of new systems have little or no
  experience with twisted pair telephone
  wire.
• Understanding Inside Wiring is relatively
  simple.

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Some History

• Prior to 1984, ILECs (Incumbent Line
  Exchange Carrier) performed virtually all
  premise installation.
• Nationwide Bell system broken up in 1984.
  Premise wiring was now the responsibility
  of the customer.
• Market became flooded with companies
  offering this service.
• Cable types, quality, and installation
  methods began to vary.

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Inside Wire Characteristics

• Age of premise will often determine what type
  of inside wiring is installed.
• Wiring can vary from single pair with no
  twist, to Category 6 cable-multiple pairs
  with tight twist.
• Primary requirement for inside wiring is that
  the wire pairs are twisted.
• The only difference between Cat 3 and Cat 5 is
  the number of twists per inch.

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Inside Wire Characteristics
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Inside Wiring Configurations

• Four types of wiring configurations
• Home Run
• Loop Through/Daisy Chain
• Star Cabling Method
• Shared Run
• The 2 most common

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Inside Wiring Configurations
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Inside Wiring Configurations
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Inside Wiring Configurations
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Inside Wiring Configurations
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Pair Quality

• What is a good telephone wire pair?
• Electrically balanced
• Correctly terminated
• Insulation Resistance is 3M?

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Pair Quality

• Electrically Balanced
• Length of Tip wire and Ring wire are equal.
  Twist is consistent along the entire length of
  the pair.
• - The Tip side of the pair is a
  mirror image of the Ring side
  of the pair.

• Properly Terminated
• - Tip and Ring wires are terminated
  correctly with respect to
  polarity.
• Tip and Ring wires are terminated in the
  correct order at a jack or splice point.

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Pair Quality

• Insulation Resistance
• Measure of how well the Tip and Ring
  conductors are isolated from each other.
• Over time, tip wire can corrode due to
  electrolysis. Ring wire is sucking
  electrons from it.
• Should be ³ 3M?.

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Inside Wiring Problems

• What kind of problems/faults will you
  encounter on inside wire?
• Shorts
• Grounds
• Opens
• High Resistance Open - High Joint
• Crosses
• Splits
• Transpositions
• Faulty Jacks
• Customer Equipment

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Inside Wiring Problems

• Shorts - An electrical connection between
  conductors of the same pair.
  
• Common causes
• 1. Insulation breakdown
• 2. Physical damage
• 3. Faulty installation (staple punctures,
  nicked or cut cable, etc.)
• 4. Careless upgrades/repairs

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Inside Wiring Problems

• Shorts - An electrical connection between
  conductors of the same pair.
  
• Common problems caused by a short
• 1. No Dial Tone
• 2. Bells Do Not Ring
• 3. Bells Ring Once
• 4. Ring No Answer

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Inside Wiring Problems

• Grounds An electrical connection between
  one or both conductors to a source
  of ground.
• - Common causes
• 1. Contact with a grounding circuit
• 2. Contact with the Tip side of a working
  pair

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Inside Wiring Problems

• Grounds An electrical connection between
  one or both conductors to a source
  of ground.
• - Common problems caused by a Ring Ground
• 1. No Dial Tone
• 2. Bells Do Not Ring
• 3. Bells Ring Once
• 4. Ring No Answer
• 5. Noisy/Hum

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Inside Wiring Problems

• Grounds An electrical connection between
  one or both conductors to a
  source of ground.
• - Common problems caused by a Tip Ground
• 1. Roar
• 2. Noisy Hum

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Inside Wiring Problems

• Opens - An electrical discontinuity (break) in
  one, or both wires in a pair.
  They usually
• 1. Are man-made
• 2. Occur at a splice
• 3. Are fully open, but may be partially open

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Inside Wiring Problems

• Opens - An electrical discontinuity (break) in
  one, or both wires in a pair.
• - Common problems caused by an Open
• 1. No Dial Tone

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Inside Wiring Problems

• High Joint - Also termed High Resistance Open
  and Series Resistance
  Fault. It is a wire, splice or connection
  point deteriorated by corrosion
  to the point that it is almost open. -
  Common symptoms are
• 1. Noisy static
• 2. No dial tone
• Note Most common cause of high joints are bad
  splices.

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Inside Wiring Problems

• Crosses - A wire from one pair making an
  electrical connection to the
  wire of another pair.
• Example The Tip wire of one pair touching the
  Tip or Ring wire of another pair. Most common
  causes are the same as a Short.

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Inside Wiring Problems

• Crosses - A wire from one pair making an
  electrical connection to the
  wire of another pair.
• - Common problems caused by a cross
• 1. Noisy Static
• 2. Hears Others On Line

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Inside Wiring Problems

• Splits - A splicing error between two wire
  pairs where a wire of one pair is connected to
  the wire of another pair. Split pairs
• 1. Usually occur at a splice point
• 2. Usually are adjacent to each other
• 3. Are a major cause of crosstalk

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Inside Wiring Problems

• Transpositions - A splicing error between two
  pairs of wire where
  the wires of one
  pair are swapped with the other.
  - Transposed pairs
• 1. Usually occur at a splice point
• 2. Usually are adjacent to each other

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Inside Wiring Problems

• Transpositions - A splicing error between two
  pairs of wire where
  the wires of one
  pair are swapped with the other.
  - Common problems caused by a
  transposition
• 1. No Dial Tone

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Inside Wiring Problems

• Customer Equipment - Low quality phones,modems
  and fax machines are generallyassociated with
  excessive line noise.

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Test Equipment?

• To Troubleshoot Inside Wire youll need
• Volt/Ohm Meter or MultiMeter
• Tone Probe
• Butt Set

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VOM/MM
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Tone Probe
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Butt Set
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Test Equipment - VOM/MM

• Functions typically found on a VOM or Multimeter
• AC Voltage
• DC Voltage
• Resistance (non-Leakage type)
• Capacitance

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Test Equipment - VOM/MM

• Specialized Volt/Ohm Meter (VOM) and/or
  Multi-Meter (MM) for telephony.
• Best if the unit has some type of Balance test.
  Very effective for finding intermittent
  faults. Also called a Stress Test.
• Also need to have a high DC Voltage (90
  150Vdc) insulation resistance test. In the
  telephony world this test is referred to as a
  Leakage Test.
• Fault analyzer will reveal most faults (if
  any) present on the pair.

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A Trouble I Can

• See
• Hear
• Is a trouble I can find/repair!

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A Trouble I Can

• Not see
• Not hear
• Is a trouble that will drive Me crazy
• and drive the Companys Repeat
• Report Rate through the roof!!!!!

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Sidekick VOC Stress Test

• Stress Test is effective in identifying
• Those faults you can not see and can not hear!
• Or those faults you may know as intermittent!

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Sidekick VOC Stress Test

• In simple terms, the patented Sidekick Stress
  Test excites the pair with 0-90 dBrnC of Power
  Influence. If the pair is electrically
  unbalanced, this Power Influence will create
  noise that is then measured as Stressed Noise on
  the Sidekick. If the pair is electrically
  balanced, the Power Influence will have no effect
  and the Sidekick will read Stressed Noise in the
  Good range.

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Sidekick VOC Stress Test

• The Sidekick VOC identifies the following forms
  of trouble
• Single sided opens
• High resistance opens
• Ground
• Crosses (to either working or non-working
  pairs)
• Splits
• Noisy CPE

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Sidekick VOC Stress Test
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VOM/MM - Leakage Test

• CATV Leakage test
• - Measurement of signals radiating from within
  the cabling into the atmosphere.
• Telephony Leakage test
• High DC voltage (90-150 Volts) insulation
  resistance test. Measures insulation resistance
  between the tip and ring wire pair.

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VOM/MM Leakage Test

• Leakage test is effective in identifying
• Shorts
• High Joints
• Crosses
• Opens
• Very effective in finding Shorts and High
  Joints
• caused by galvanic corrosion.

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VOM/MM - Leakage Test

• Galvanic corrosion acts as a pseudo-insulator.
  It tricks
• most non-telephony multimeters into
  indicating
• satisfactory insulation readings.
• Telephony based meters with leakage test use
  high DC voltage that can break down this
  corrosion and expose the fault.

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Troubleshooting

• No Dial Tone
• Open
• Short across pair
• Ground fault (on ring)
• High Joint
• Moisture in cable or splice

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Troubleshooting

• Static/Hum on Line
• Short across pair
• Ground fault (on tip)
• Moisture in cable or splice
• High Joint
• Customer Equipment
• Crossed with AC line
• Induction from AC line

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Troubleshooting

• Hears others on the line (Crosstalk)
• Crossed with another working pair
• Split with another working pair
• Operates OK for short time, then has static
• High Joint
• Moisture in splice or cable
• Customer Equipment

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Troubleshooting
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Troubleshooting

• Connect VOM/MM at NID. Use Stress Test and
  observe reading.

Network Interface Device
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Troubleshooting

• Disconnect all CPE and observe Stress Test.
  If reading dropped fault is in CPE. If not,
  fault is in Inside Wire or Line Cords.

Network Interface Device
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Troubleshooting

• Remove each Inside Wire connection from the
  NID. Test each with Stress Test. Wire that
  has higher reading is faulted.

Network Interface Device
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Troubleshooting

• Disconnect Line Cords from wall jacks on
  faulted wire. Test wire again with Stress Test.
  If reading drops, fault is in one of the base
  cords. If it remains the same, fault is in
  Inside Wire.

Network Interface Device
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Sidekick VOC

• Questions
• Answers

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Contacts

• Terri Pettit
• Eastern Reg. Sales Mg.
• 469-358-0897

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• Thank You!