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(using the Main Unit's Cable Test jack) and tracing it using The
Remote Probe. The remote Probe will emit a tone when it is close to
(or touching) the cable under test.
Note: The tone generator places a tone on a pair of wires at a time
(first 1,2 then 3,6 then 4,5 them 7,8). This is the AT&T 258A wiring
scheme. If all 4 pairs are wired, the tone will sound rather steady. If
only 1 pair is wired, the tone will only be on for 1/4 of the cycle.
Tips for tracing tones:
Tracing tones is usually best on wires that are disconnected from
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any power source. Existing signals on lines can sometimes
interfere with the tone signal.
You will notice that the Main Unit's tone generator circuitry steps
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the tone from one pair to the next (i.e. "1,2" then "3,6" then "4,5"
then "7,8'). Listening to the missing gaps in the tone signal can
sometimes be helpful in understanding a problem.
Maximum sensitivity occurs when the tip is held parallel to
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the conductors carrying the tone and the volume is high.
Caution: electrical cables carry a wide variety of signals. They are
dangerous. Telephone circuits employ a –48V battery voltage. When
ringing, voltages are much higher (90 V RMS on top of the –48V).
Telephone signals should not be on the same cables as LAN signals
but exercise caution. If you are unsure of safe procedures, do not
continue.
Determining the pairs that are wired. Once the cable has been
located by tracing the tone, the Remote Probe's RJ45 jack is used
to test the wiring of the cable. The Remote Probe decodes the wiring
data sent by the TVR1000 Main Unit's Cable Test jack (the
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same jack that transmits the tone) and displays the results of the
decoding on the Remote Probe's four LEDs. The LEDs meaning is
defined by it labeling ("1,2", "3,6", etc); color (Off, Green or Red) and
direction of scanning (top-to-bottom or bottom-to-top).
Labeling: If the LED labeled "1,2" is ON, wire pair 1, 2 is wired.
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The other LED labeling is the same in function.
Color: If the LED lights green, the pair is OK. If the LED lights
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red, there is a wire fault in that pair (most likely that the wires are
inverted i.e. pair 1,2 is wired 2,1). This is indicated on the
faceplate as "Green OK and "Red Fault."
Direction of scan: If the LEDs are lighting in a left-to-right
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direction (from the left of the probe toward the right of the probe),
the cable pairs are wired in a straight thru pattern. If they are
lighting in the opposite direction, the pairs are wired in a
crossover configuration. This is denoted on the faceplate by the
"=" symbol for "Straight" and "X" for "Crossover."
Shorted pairs: If a pair is shorted across itself, it will show up as
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non existent pair (LED will be OFF). If the short is across pairs it
will either light one pair red and the other green (simultaneously)
or an individual LED will alternate red and green. Summary: Any
red color indicates a wiring problem.
See the Appendix A for more information about the subject of wiring.
The Remote Probe's "One-step process." In a ONE-STEP PRO-
CESS, this unique device traces a tone, then displays the pairs con-
figuration of the cable without requiring the substitution of another
tester or an additional walking trip to the tone generator location.
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