Resistance Measurements - Extech Instruments MA440 User Manual

Resistance Measurements
WARNING: Please remove power to the circuit under test and discharge all capacitors
before taking resistance or continuity measurements. The meter will display OL if the circuit
under test is an open circuit of if the measurement exceeds the maximum range of the meter.
Do not input a voltage >30V AC or DC.
1. Turn the function switch to the Resistance Ω position.
2. Use the M (mode) button to select the ohm Ω display symbol.
3. Insert the black test lead banana plug into the negative (COM) jack. Insert the red test
lead banana plug into the positive (Ω) jack. See Fig. 7.
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 that the rest of the circuit will not interfere with the
resistance reading.
5. Read the resistance in the display. The display will indicate the proper decimal point and
value.
6. The MAX‐MIN function is available in this mode on the MA443 and MA445. Short press
the MAX MIN button to step through MAX MIN readings. Long press to exit the mode.
NOTES:
For low resistance measurements, the probe error (0.1~0.2Ω) should be zeroed using the
relative mode. Short circuit the test probes and press the REL button before taking
measurements.
When measuring resistance >1MΩ the meter may require several seconds to stability the
displayed reading.
MAX-MIN
For MA443 and
MA445
Fig. 7 – Resistance and Continuity Measurements
11
MA44x‐en‐GB_V1.0 8/16