Ac And Dc Voltage Measurements - Extech Instruments MA440 User Manual

AC and DC Voltage Measurements
WARNING: Do not apply > 600VAC/DC between the meter terminals and ground.
CAUTION: When connecting the test leads to the circuit or device under test, connect
the black lead before the red lead; when removing the test leads, remove the red lead before
the black lead.
1. Set the function select switch to the Voltage position
2. Use the M (Mode) button to select AC or DC Voltage.
3. Insert the black test lead banana plug into the negative (COM) jack and the red test lead
banana plug into the positive (V) jack.
4. Touch the test probe tips to the circuit or under test. For DC measurements in the range
of 400mV, use the Relative mode to zero the display before taking a measurement.
5. Read the voltage in the LCD. The display will indicate the proper decimal point and value.
6. Relative (REL) mode can be used to set a reference reading from which subsequent
readings will be offset (reference reading – actual reading = displayed reading). Long
press the REL button to activate/deactivate the relative mode.
7. The MA440 can display the frequency (Hz) or duty cycle (%) of the measured voltage.
Short press the Hz % button to toggle frequency and duty cycle readings. For the
MA443/MA445 see the dedication section on Frequency for frequency and duty cycle.
8. The MA443 and MA445 record MAX and MIN readings. Short press the MAX MIN button
to step through the MAX MIN readings. Long press the MAX MIN button to exit.
9. Short press the H button to freeze/unfreeze the displayed reading. Long press to
activate/deactivate the display backlight.
NOTES: The MA440 displays OL when the input exceeds 1000V. The MA443/MA445 display
when the tested voltage is > 30V and sounds the buzzer when the voltage input is > 600V.
AC
DC
Fig. 5 MA443/MA445 Voltage test Fig. 6 – MA440 Voltage testing
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10
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AC
DC
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