Sealey MM18 - Manual (Page 4)

4. OPERATING INSTRUCTIONS
4.1. MEASURING DC VOLTAGE
4.1.1. Set the function switch to the V position.
4.1.2. Set the range to the desired position. If the magnitude of the voltage to be measured is not known beforehand, set the range
switch to the highest range first and then reduce it range by range until satisfactory resolution is obtained.
4.1.3. Connect the test leads across the source or circuit to be tested.
4.1.4. Read the reading on the display. The polarity of the red test lead connection will be indicated as well.
NOTE To avoid electric shock to you or damage to the meter, DO NOT measure a voltage higher than 250V.
4.2. MEASURING AC VOLTAGE
4.2.1. Set the function switch to the V position.
4.2.2. Set the range switch to 250V or 200V range position.
4.2.3. If the magnitude of the voltage to be measured is not known beforehand, set the range to the highest first and then reduce it
until a satisfactory resolution is obtained.
4.2.4. Read the reading on the display.
NOTE To avoid electric shock to you or damage to the meter, DO NOT measure a voltage higher than 250V.
4.3. MEASURING DC CURRENT
4.3.1. Set the function switch to A position.
4.3.2. Set the range switch to the 200mA range position.
4.3.3. Turn off the circuit to be tested. Then discharge all capacitors.
4.3.4. Break the circuit path to be tested, then connect the test leads in series with the circuit.
4.3.5. Turn on the power to the circuit, then read the reading on the display. The polarity of the red test lead connection will be
indicated as well.
4.4. MEASURING RESISTANCE
4.4.1. Set the function switch to position.
4.4.2. Set the range switch to the desired resistance measuring range position.
4.4.3. Connect the test leads across the object to be measured.
4.4.4. Read the reading on the display.
NOTE:
1. For measurements > 1MΩ, the meter may take a few seconds to stabilise a reading. This is normal for high resistance
measurements.
2. When the test leads are in open circuit state , “1” will be dsplayed as an overrange indication.
3. Before measurement, disconnect all power to the circuit to be tested and discharge all capacitors thoroughly.
4.5. DIODE TEST
4.5.1. Set the function to the position.
4.5.2. Set the range switch to the position.
4.5.3. Connect the red test lead to the anode of the diode to be tested and the black lead to the cathode of the diode.
4.5.4. The display shows the approximate forward voltage drop of the diode. If the connection is reversed, “1” will be shown on the
display.
4.6. CONTINUITY TEST
4.6.1. Set the function switch to the position.
4.6.2. Set the range switch to the position.
4.6.3. Connect the test leads across the circuit to be tested.
4.6.4. If the resistance is less than about 30Ω, the built in buzzer will sound.
NOTE Before test, disconnect all power to the circuit to be tested and discharge all capacitors thoroughly.
© Jack Sealey Limited
5. MAINTENANCE
5.1. Periodically wipe the case with a damp cloth and mild detergent. DO NOT use abrasives or solvents.
5.2. BATTERY AND FUSE REPLACEMENT
5.2.1. When the symbol ” “ appears on the display, the batteries are low and must be replaced immediately. To replace the
batteries remove the screws in the back cover and remove the back cover. Remove the batteries and replace with batteries
of the same type (1.5V button cell LR44 or equivalent). Make sure the polarity connections are correct (see the indication on
the bottom of each cell compartment). Reinstall the back cover and its screws.
The fuse rarely needs to be replaced and is blown as a result of operator’s error. To replace the fuse, remove the back cover
(see above) replace the fuse with one of the same rating. Reinstall the back cover and its screws.
This meter uses 250mA/250V, fast, Ø5x20mm fuse.
 WARNING Remove all leads from the circuit under test before opening the back cover.
Original Language Version MM18 Issue No:2(I)-09/09/14