Peak Button
This function is used to measure the peak value of an AC current signal. To use
this function, select the current range and press the PEAK button. The "PEAK"
indicator will appear on the display. When the instrument detects current, the
peak value will be displayed and held in the internal memory. To cancel the
function, press the PEAK button once again.
Hold Button
Press (HOLD) to toggle in and out of data hold mode. In the data hold mode, the
"HOLD" indicator is displayed and the last reading is frozen on the display. Press
the (HOLD) button again to exit and resume taking readings.
RANGE Button
Press the RANGE button to select the manual ranging modes. The “
” indicator
will be displayed. In the manual ranging mode, each time the RANGE button is
pressed, the range and the input indicator change. To exit the manual ranging
mode and return to autoranging, press and hold the RANGE button for 2 sec-
onds. The “
” indicator clears from the display.
When the rotary switch is set to
or
, press the RANGE button to toggle
between audible continuity and diode test modes.
7
WARNING
The clamp jaws are designed to take current measurements on circuits
with a maximum voltage difference of 500VAC between any conductor
and ground potential. Using the clamp jaws for current measurements
on circuits above this voltage may cause electric shock, instrument
damage and / or damage to the equipment under test. Before
measuring current, make sure that the test leads are removed from the
instrument.
The clamp jaws are overload protected up to 500VAC for up to 1 minute.
Do not take current readings on circuits where the maximum current
potential is not known. Do not exceed the maximum current that the
instrument is designed to measure.
3.3 RESISTANCE MEASUREMENTS
1. Isolate any power which may be present at the resistance to be measured and
discharge any capacitors. Any voltage that may be present during a resistance
measurement will cause inaccurate readings and could damage the meter if the
voltage exceeds the overload protection of 500V DC or AC.
2. Insert the black & red test leads into the COM and
Ω
input terminals respectively.
3. Select the desired ohms (
Ω
) range
4. Connect the black & red test probe tips to the circuit or device under test,
making sure it is de-energised first.
5. Open circuits will be displayed as an overload condition.
6. Test lead resistance can affect low resistance measurements and should be sub-
tracted from resistance measurements for accuracy. Select the lowest
resistance range and short the test leads together. The value displayed is the
test lead resistance which should subtracted from the resistance measurement.
7. After completing the measurement, disconnect the test leads.
3.4 CONTINUITY TESTING
1. Select the (
) /
) position by turning the rotary selector switch and press
the "range" button to enter continuity testing.
2. Follow steps 2 & 4 as for resistance measurements
3. The clampmeter emits a tone when measuring resistance of approximately 20
Ω
or less. After measurements have been carried out, disconnect the test
leads from the circuit and from the input terminals of the clampmeter.
8
WARNING
Attempting resistance or continuity measurements on live circuits can
cause electrical shock, damage to the instrument and damage to the
equipment under test. Resistance measurements must be made on
de-energised (DEAD) circuits only, for maximum personal safety. The
electronic overload protection installed in this instrument will reduce
the possibility of damage to the instrument but not necessarily avoid
all damage or shock hazards.
3.5 DIODE TESTING
1. Set the (
/
) position by turning the rotary switch and press the
RANGE button to enter Diode testing.
2. Follow steps 2 & 4 as for resistance measurements.
3. The RED lead should be connected to the anode and the black lead to the
cathode. For a silicon diode, the typical forward voltage should be about 0.6V or
0.3V for germanium diode.
4. If the diode is reverse biased or there is an open circuit, the display shows
"OL"
3.6 FREQUENCY MEASUREMENTS
1. Set the rotary selector switch to the desired position
2. Plug the black and red test leads into the "COM" and "Hz" input terminals
respectively
3. Determine that the amplitude level of the signal to be measured is not greater
than the input voltage limit (500Vac/Vdc). The signal amplitude must also be
greater than the sensitivity level.
4. Attach the probe tips to the points across which the frequency is to be
measured, and read the result directly from the display.
5. Disconnect the test leads.
Auto Power Off
Automatic power-off extends the life of the battery by turning the meter off after
approximately ten minutes of inactivity. To Turn the meter back on, simply push
the range button, or turn meter off then back on.
9
CAUTION
Measurements must only be made with the circuit power OFF
4. MAINTENANCE
Maintenance consists of periodic cleaning and battery replacement.
The exterior of the instrument can be cleaned with a dry clean cloth
to remove any oil, grease or grime. Never use liquid solvents or
detergents.
Repairs or servicing not covered in this manual should only be
performed by qualified personnel.
4.1 Cleaning
The CM56 may be cleaned using a soft dry cloth. Do not use abrasives,
solvents, or detergents, which can be conductive. Allow to dry completely
before using.
4.2 Repair & Service
There are no user serviceable parts in this unit. Return to Martindale Electric
Company Ltd if faulty. Our service department will quote promptly to repair any
fault that occurs outside the guarantee period.
Before the unit is returned, please ensure that you have checked the unit and
associated leads thoroughly for flat batteries (check & replace), blown fuses
(check & replace) and other poor connections.
4.3 Storage Conditions
The clampmeter should be kept in warm dry conditions away from direct sources
of heat or sunlight, and in such a manner as to preserve the working life of the
unit. It is strongly advised that the unit is not kept in a tool box where other tools
may damage it.
5. WARRANTY
The CM56 is guaranteed against faults in manufacture and materials for 24
months from date of invoice and will be rectified by us free of charge, provided
the unit has not been tampered with and is returned to us with its housing
unopened. Damage due to dropping, abuse or misuse is not covered by this
guarantee. Batteries and fuses are not covered by this guarantee.
10