Lesson 2/Learning Event 3
a. Read and study. There is no substitute for knowledge about the test
equipment used in circuit conditioning. To gain this knowledge, technicians
must read and study all available information.
This must be done before
starting any test so that the test method and equipment operation is
understood. Knowledge will also give an awareness of any special measures
that should be taken to safeguard equipment and personnel.
b. Preliminary check.
Circuits or segments of circuits being tested
must not interfere with traffic flow, but must otherwise be under normal
working conditions.
Failure to test under working conditions may require
retesting. As a preliminary to other test procedures, a listening check of
the circuit with either high-impedance headphones or an oscilloscope may be
useful in indicating the presence or absence of tones or other conditions
that could interfere with test results. Further, a normal test of the line
for general line condition (shorts, foreign battery, grounds, etc.) with a
wire test set is definitely in order as a preliminary check.
c. Grounds. When test equipment and circuits under test require ground
connections, the connections must be made to a common ground point to avoid
creating ground return loops which can pick up interfering currents.
d. Coordination. Circuit conditioning can be successful only as long
as technicians at both ends of a circuit know what is going on.
Communication between them must be established and maintained during the
entire operation.
A circuit for this purpose must be independent of the
order wire, because the technical controller will use the order wire.
Further, both technicians involved in circuit conditioning must realize that
the one at the receiving termination is responsible for all circuit
conditioning actions in his direction of signal flow.
Control of the
circuit reverts to the other terminal for the opposite direction of signal
flow. Coordination between the conditioning technicians and the technical
controllers is an important function, too, so as to safeguard channels of
traffic flow.
A technician who carelessly interrupts flow of traffic
irritates his associated technical controller.
e. Treatment of equipment. Treat equipment with great care; these are
precision scientific instruments.
Do not allow unskilled personnel to
operate the test sets. Test equipment connections and switch positions must
be checked thoroughly before applying power, and power should come from a
filtered power source when possible.
Further, test equipment must be
properly calibrated at sufficiently close intervals to assure accurate
readings.
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