Ac Current Measurements; Resistance Measurements - Extech Instruments EX420-NIST User Manual

AC CURRENT MEASUREMENTS

CAUTION: Do not make current measurements on the 20A scale for longer than 30 seconds.
Exceeding 30 seconds may cause damage to the meter and/or the test leads.
1. Insert the black test lead banana plug into the negative COM jack.
2. For current measurements up to 4000µA AC, set the function
switch to the yellow µA position and insert the red test lead
banana plug into the µA/mA jack
3. For current measurements up to 400mA AC, set the function
switch to the yellow mA position and insert the red test lead
banana plug into the µA/mA jack.
4. For current measurements up to 20A AC, set the function switch
to the yellow 20A range and insert the red test lead banana plug
into the 20A jack.
5. Press the SELECT button to indicate "AC" on the display.
6. Remove power from the circuit under test, then open up the
circuit at the point where you wish to measure current.
7. 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.
8. Apply power to the circuit.
9. 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 green  position.
2. Insert the black test lead banana plug into the negative COM jack.
Insert the red test lead banana plug into the positive  jack.
3. Press the SELECT button to indicate on the display.
4. 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.
5. Read the resistance in the display.
netzerotools.com
8
netzerotools.com
EX420-EU-EN v3.3 08/13