EXTECH DM220 [3/15] Operating instructions

DM220 V3.0 01/06 3

Operating Instructions

WARNING: Risk of electrocution. High-voltage circuits, both AC and DC, are very

dangerous and should be measured with great care.

1. ALWAYS turn the function switch to the OFF position when the meter is not in

use.

2. If “OL” appears in the display during a measurement, the value exceeds the

range you have selected. Change to a higher range.

NOTE: On some low AC and DC voltage ranges, with the test leads not connected

to a device, the display may show a random, changing reading. This is normal

and is caused by the high-input sensitivity. The reading will stabilize and give a

proper measurement when connected to a circuit.

AC/DC VOLTAGE MEASUREMENTS

CAUTION: Do not measure AC/DC voltages if a motor on the circuit is being

switched ON or OFF. Large voltage surges may occur that can damage the

meter.

1. Set the function switch to the V/Hz/% position.

2. Press the MODE button to indicate “AC” or “DC” on the display.

3. 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.

4. Read the voltage in the display.

AC/DC CURRENT MEASUREMENTS

1. For current measurements up to 4000µA AC/DC, set the function switch to the

µA position

2. For current measurements up to 200mA AC/DC, set the function switch to the

mA position.

3. Press the MODE button to indicate “AC” or “DC” on the display.

4. Remove power from the circuit under test, then open up the circuit at the point

where you wish to measure current.

5. 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.

6. Apply power to the circuit.

7. Read the current in the display.

RESISTANCE MEASUREMENTS

WARNING: To avoid electric shock, disconnect power to the unit under test

and discharge all capacitors before taking any resistance measurements.

Remove the batteries and unplug the line cords.

1. Set the function switch to the Ω CAP position.

2. Press the MODE button to indicate Ω on the display.

3. Touch the test probe tips across the circuit or part under test. It is best to

disconnect one side of the part under test so the rest of the circuit will not

interfere with the resistance reading.

4. Read the resistance in the display.