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2. USE
This instrument is a digital tester. It measures AC and DC
voltages, alternating currents, resistances, and capacitances.
It also has a continuity function and a diode function and can
be used for non contact voltage detection.
2.1. INSTRUMENT TEST
Before making any measurements, test all of the functions
of the instrument.
To switch the instrument on, turn the switch to any position.
All segments of the display unit light (Figure 6) and the
instrument emits a continuous beep.
If the battery voltage is too low for correct operation of the
instrument, the
symbol is displayed.
If the battery voltage is much too low, the display unit
will not light.
In both cases, it is time to replace the batteries (see § 4.2).
With the inputs disconnected, set the switch to
W
. The
display unit indicates - - - -.
Connect the red probe tip to the
+
terminal and the black
probe tip to the
COM
terminal. Bring the two probe tips
together, so that they touch. The instrument indicates a
resistance near zero and emits a continuous beep.
Set the switch to
V
and measure a known voltage.
If the results of these four tests are correct, your instrument
is ready for use.
2.2. VOLTAGE
Connect the red probe tip to the
+
terminal and the black
probe tip to the
COM
terminal.
Set the switch to
V
.
Keep your hands behind the guards of the device and of
the test probe (Figure 9).
Place the test probes on the element to be tested and
maintain a firm contact.
The voltage is displayed (Figure 7).
If the voltage is > 30V, the instrument displays
, indicating
that the voltage is dangerous.
As default, the instrument is in automatic mode (
SCAN
). If the
voltage is AC, the instrument displays AC. If the voltage is
DC, it indicates DC and displays its polarity.
The
Select
key is used to exit from the automatic mode (the
SCAN
symbol disappears) and display the AC voltage only, or
the DC voltage only, or to return to the automatic mode.
To determine the type of voltage (AC or DC) for a measure-
ment < 1V, exit from the automatic mode.
Do not use the C.A 757 to check for the absence of a
voltage. For that, use a VAT.
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