Ac/Dc Voltage Measurements; Resistance Measurements; Continuity Test - Extech Instruments MA640 User Manual

AC/DC Voltage Measurements

CAUTION: Do not measure voltages if a motor on the circuit is being switched ON or OFF. Large
voltage surges may occur that can damage the meter.
1. Rotate the function switch to the V position.
2. Press the MODE button to select AC or DC Voltage.
3. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive V jack.
4. Touch the black test probe tip to the negative side of the circuit.
Touch the red test probe tip to the positive side of the circuit.
5. Read the voltage value in the display.

Resistance Measurements

Note: Remove power from the device under test before making resistance measurements
Rotate the function switch to the position.
1.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive V jack.
3. Touch the black test probe tip to one side of the device.
Touch the red test probe tip to the other side of the device.
4. Read the resistance value in the display.

Continuity Test

1. Connect as described for resistance measurements.
2. Press the MODE button to select continuity
3. Touch the test probe tips across the circuit or component under test.
4. If the resistance is < 60, a tone will sound.
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