Greenlee PE930 Manuel D'instructions page 13

Troubleshooting (cont'd)
Symptom*
RFI (radio frequency
interference)
Intermittent or
variable current
* Wet cables may cause most of these symptoms and may cause multiple symptoms to appear at
the same time.
Possible Cause /
Troubleshooting Step
Split pair
Wet cables or a
bad connection
PE930 • PE945 • PE961
Explanation
An unbalanced pair near a radio transmitter will
be prone to RFI. Adding radio filters can reduce the
interference on the line (the symptom), but does not
solve the imbalance (the problem). To troubleshoot,
break the circuit down into sections and check each
section for split pairs or a resistive imbalance.
A strong amount of radio interference may trigger
the test set's excessive DC voltage alarm and
prevent connection when you attempt to go off-
hook. If this happens, listen closely for the sound of
a radio broadcast to determine if this is the cause
of the alarm. If it is necessary to make a call in
this situation, you may safely override the alarm by
holding down the TALK button for the duration of the
override tone. When the test set goes quiet, release
the TALK button and dial the number.
Note: This override procedure will not work if
the line is unpowered or if a hazardous DC voltage
is present.
Improperly removed bridge taps may also introduce
RFI. Bridge taps, which were once used for party-
line service (multiple users sharing a cable pair),
were often disconnected but left in place, with
a stub section of cable still connected. This stub
section can act as an antenna and induce radio
signals into the circuit.
If accompanied by noise, the cause is usually
wet cables.
If no noise is present, the cause is probably a bad
connection in a cross-connect or a bad connection
at the central office.
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