Sealey MM19 - Manual (Page 4)

Original Language Version
4. OPERATION
 WARNING! Risk of electrocution. High-voltage circuits, both AC and DC, are very dangerous and should be measured with
great care. Do Not measure voltages that might exceed 500 V above earth ground.
ALWAYS turn the function switch to the “ OFF” position when the meter is not in use.
NOTE! On some low AC and DC voltage ranges, with the test leads not connected to a device, the display may show a random
reading. This is normal and is caused by the high-input sensitivity. The reading will stabilise and give a proper measurement
when connected to a circuit.
4.1. DC VOLTAGE MEASUREMENTS
CAUTION: Do not measure DC voltages if a motor on the circuit is being switched ON or OFF.
Large voltage surges may occur that can damage the meter.
4.1.1. Set the function switch to the highest VDC position.
4.1.2. Insert the black test lead banana plug into the negative (COM) jack. Insert the red test lead banana plug into the positive (V)
jack.
4.1.3. 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.
4.1.4. Read the voltage in the display. Reset the function switch to successively lower VDC positions to obtain a higher resolution
reading. The display will indicate the proper decimal point and value.
4.2. AC VOLTAGE MEASUREMENTS

WARNING! Risk of Electrocution. The probe tips may not be long enough to contact the live parts inside some 240V outlets
for appliances because the contacts are recessed deep in the outlets.
As a result, the reading may show 0 volts when the outlet actually has voltage on it. Make sure the probe tips are touching
the metal contacts inside the outlet before assuming that no voltage is present.
CAUTION: Do not measure AC voltages if a motor on the circuit is being switched ON or OFF.
Large voltage surges may occur that can damage the meter.
4.2.1. Set the function switch to the highest VAC position.
4.2.2. Insert the black test lead banana plug into the negative (COM) jack.
Insert red test lead banana plug into the positive (V) jack.
4.2.3. 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.
4.2.4. Read the voltage in the display. Reset the function switch to successively lower VAC positions to obtain a higher resolution
reading.
4.3. DC CURRENT MEASUREMENTS
CAUTION: Do not make current measurements on the 10A scale for longer than 30 seconds.
Exceeding 30 seconds may cause damage to the meter and/or the test leads.
4.3.1. Insert the black test lead banana plug into the negative (COM) jack.
4.3.2. For current measurements up to 200mA DC, set the function switch to the highest DC mA
position and insert the red test lead banana plug into the (mA) jack.
4.3.3. For current measurements up to 10A DC, set the function switch to the 10A range and insert the red test lead banana plug
into the (10A) jack.
4.3.4. Remove power from the circuit under test, then open up the circuit at the point where you wish to measure current.
4.3.5. Connect test leads in series with the circuit under measurement.
4.3.6. Apply power to the circuit.
4.3.7. Read the current in the display. For mA DC measurements, reset the function switch to successively lower mA DC positions
to obtain a higher resolution reading. The display will indicate the proper decimal point and value.
4.4. 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.
4.4.1. Set the function switch to the highest Ω position.
4.4.2. Insert the black test lead banana plug into the negative (COM) jack. Insert the red test lead banana plug into the positive Ω
jack.
4.4.3. Touch the test probe tips across the circuit or component under test. It is best to disconnect one side of the component
under test so the rest of the circuit will not interfere with the resistance reading.
4.4.4. Read the resistance in the display and then set the function switch to the lowest Ω position that is greater than the actual or
any anticipated resistance. The display will indicate the proper decimal point and value.
© Jack Sealey Limited MM19.V3 Issue No: 5(I) - 16/06/14