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Using a tone generator & probe

Using a tone generator & probe

A tone generator ("toner") and probe are two of the most useful pieces of telephone testing equipment, and belong in every phone geeks tool collection. We sell many models from several manufacturers, but they all provide the same basic function -- to help you find the far end of a wire that may be inside a wall, buried in a pile of wires, or connected to one of many jacks in a patch panel, or one of many pairs on a punchdown block.

The tone generator may be thought of as a transmitter, that sends a musical tone (1kHz is typical) through a wire. The probe is a receiver, that lets you hear the tone at points along the wire run or at its far end, when its tip is close to or touching the wire that carries the tone.

Some tone generators provide other functions, such as polarity indication, power to have a conversation ("talk battery"), testing of multiple phone lines, choice of multiple tones, automatic shut-off, ringing indication, continuity testing, etc.

Most tone generators are equipped with a modular plug that will fit into phone or data jacks, and alligator clips that can be attached to bare wires, screws or clips.

Probes are also available with a range of features, but almost all modern units allow listening with either an internal speaker or a clipped-on buttset. Most have volume controls, and some offer a choice of tips, and advanced features such as signal strength indication and even phone line monitoring..

The following instructions are for use with the Aines model 240 tone generator and model 250 probe, but will also be useful with other similar products.

3. Use.
3.01 Before using the 240 Tone Test Set, check to make sure the battery is in good condition.
  This can be accomplished by putting the switch in the "Continuity" (towards the LED)
  position and touching the two 6A clips together. The LED should glow GREEN.
3.02 OFF Position of the function switch (centered). In the OFF position of the function
  switch, the 240 Tone Test Set checks the polarity of the telephone line. When the RED
  test lead is connected to the RING side of the circuit and the BLACK lead is connected
  to the TIP side of the circuit, The LED on the front of the test set will glow GREEN
  showing NORMAL polarity. If the leads are reversed, the LED will glow RED indicating
  reverse polarity.
3.03 Similarly, when the modular plug is connected to a telephone modular jack, GREEN
  indicates NORMAL polarity and RED indicates REVERSE polarity.
3.04 The LED will light YELLOW if the modular jack has normal polarity and the yellow lead
  is grounded.
3.05 The LED will light RED if the modular jack has reverse polarity even if the yellow lead
  is grounded.
3.06 The 240 Tone Test Set in the OFF position may also be used to detect ringing voltage
  on the line. When ringing voltage is present, the LED will flash YELLOW at the ringing
  rate per second.
3.07 Plugging the telephone cord into the modular jack on the 240 Tone Test Set
REVERSES THE CONNECTION to the instrument. Connected in this way, RED
  indicates NORMAL and GREEN indicates REVERSE polarity.
4. Continuity Functions.
4.01 In the CONT position of the Function switch (switch towards the LED), the 240 Tone Test
  Set can be used to check the continuity of the line or circuit. When the clip leads are
  connected to the circuit, the LED will glow GREEN to show there is a path through
  the circuit.
4.02 The brightness of the LED indicates how much resistance is in the circuit. Zero
  resistance, a short circuit, results in the greatest brightness. There will be noticeable
  output even for circuit resistances as much as ten thousand ohms.
4.03 The Model 240 may also be used in the CONT position to supply talk power to a
  telephone line. It will provide about three (3) volts to a six hundred (600) ohm line.
  Be sure your butt set will operate at 3 volts talk battery.
5. Tone.
5.01 In the TONE position (switch away from the LED) the Model 240 serves as a tone
  generator to inject a signal which may be used for pair tracing on the telephone line.
5.02 Two different tones, a steady tone or an alternating (warble) tone may be selected by
  the small switch on the edge of the circuit board located near the battery. The back
  cover must be removed to access the switch.
5.03 In the steady (STDY) position, a steady 1000 hertz tone is generated.
5.04 In the alternating (ALT) position, alternating 500 hertz and 1000 hertz tones are
  generated. The switching rate is about 1.2 complete cycles per second. This is
  sometimes referred to as a "warble" tone.

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Installation and repair personnel with a test probe can accomplish the following.....
a. Identify individual pairs in the outside plant cables at terminals, closures, pedestals, etc.
b. Identify station wiring, cables, or key equipment in closets, distribution terminals, etc.
c. Identify drop wires or buried service wires at terminals and pedestals.
d. Locate pre-wiring after wall covering is installed.
e. Locate opens in wires.
f. Locate live AC wiring in walls without the need for a tone generator.
Tone Source
The test probe requires a tone source in the range of 500 to 1000 hertz that can be applied at the CO or locally. Performance of the test probe is better with a modulated tone.
NOTE: Whenever possible, disconnect the conductors under test from the CO or local phone system to prevent circuit equipment and customer interference from the locally applied tone source.
Connect the tone source to a metallic circuit, either across a cable pair or split-cable pairs. Connecting the tone to ground dissipates the signal causing conductor identification difficulty.
When using the test probe, do not touch the metal tip with the hand or finger, or a reduction in the volume of tone heard in the Butt Set or speaker will result (the human body "loads down" the circuit).
Tone Probe Operation Check
Before using the test probe, check it for operation. Connect one of the buttset alligator clips to either contact tab (one of the "ears"), set the buttset to the TALK position, and place the receiver to your ear. Connect the other buttset clip to the other "ear" (needle point of the spring clip should fit into the hole on the "ear"). A battery "click" should be heard in the buttset receiver. Where available, the condition of the test probe can be determined further by holding it near a source of induced noise such as fluorescent lamps, motors, dial tone, computer or TV screens, etc. Although the probe is normally used with the butt set switch in the TALK position, it also functions in the MONITOR position, but at a reduced volume. At times, this reduced volume may make it easier to identify the proper cable pair.
CAUTION: The test probe need only be held near a noise source to check operation.
NEVER touch the metal tip to exposed power sources such as electrical outlets.
Anytime the probe is not in use, remove the butt set clips from the ears to prevent battery drain.
CAUTION: Never connect a test probe across a working line with the switch of the butt set in the MONITOR position. The probe may be damaged.
Identifying Wiring or Cabling
With the tone connected, identify a specific line pair from among a large number of pairs by inserting the test probe tip into groups of wires until tone is heard. In multi-binder cables, insert the test probe tip into groups of wires comprising the binder group until the tone is heard. Once generally located, touch the individual conductors with the probe tip until the tone is distinctly heard (loudest) indicating the conductors under test.
As a final test, place the probe tip parallel to and against the conductors being identified. Tone should be heard, indicating the conductors under test.
Locating Opens
Locate open circuits with the test probe in a manner similar to identifying conductor pairs. With the tone applied and the conductor pair identified, move the test probe along the pair until a definite lessening of the tone is heard, which indicates the open has been passed. If only one conductor of a pair is believed open, any slight drop in the tone volume is an indication that the open has been passed. The tone may carry past the open on the good conductor.