Clarke CDM-50 User manual

DIGITAL
MULTIMETER
OPERATING
INSTRUCTIONS
MODEL CDM-50
Part No.4500065
0607

DATA HOLD FUNCTION
When this button is pressed, the last reading to be taken will be held on the
display, and D-H will appear alongside it, until either the button is pressed again,
or the function switch is used.
MAINTENANCE
Battery and/or fuse replacement should only be done after the test leads have
been disconnected, and power is OFF.
BATTERY AND FUSE REPLACEMENT
Note the condition of the 9-volt battery using the procedure described above. If
the battery needs to be replaced, unscrew the three screws and remove the
back cover. Replace the spent battery with one of the same type (NEDA. 1604,
6F22 or equiv).
The same procedure is used to replace the fuses. Ensure the replacement is of
the same size and value as the original. 0.3A/250V or 10A/250V DC, fast blow
type.
REPLACEMENT PARTS
1. Test Leads (pair) Part No. CH5001
2. HoIster (Size AA) Part No. CH5004
3. Fuse (0.3A/250V) Part No. CH5002
Fuse (10A/250V) Part No. CH5003
CE STANDARDS
This unit complies with 73/23/EEC, 89/336/EEC.
For Spare Parts and Service, please contact your nearest dealer,
or CLARKE International, on one of the following numbers.
PARTS & SERVICE TEL: [phone]
PARTS & SERVICE FAX: [phone]
or e-mail as follows:
PARTS: [email protected]
SERVICE: [email protected]
PARTS & SERVICE CONTACTS
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When disposing of this product, do not dispose of with general waste. It must be
disposed of according to the laws governing Waste Electrical and Electronic
equipment, at a recognised disposal facility.

Thank you for purchasing this Clarke Multi-Range Digital Multimeter.
This instrument is a compact, rugged, battery operated hand held, digital multimeter.
It is designed to measure AC and DC voltage, AC and DC current, Resistance, Diode,
Capacitance, for testing Transistors, and has an Audible Continuity function. The
display is a 3¾ digit, 3260 count LCD, and a linear bargraph. The dual-speed A-D
converter ensures a high speed, accurate performance. It is an ideal instrument for
use in the field, workshops, and for hobby and home applications.
GUARANTEE
This product is guaranteed against faults in manufacture for 12 months from purchase
date. Keep your receipt as proof of purchase. This guarantee is invalid if the product
has been abused or tampered with in any way, or not used for the purpose for
which it is intended. The reason for return must be clearly stated. This guarantee
does not affect your statutory rights.
SAFETY
Read this information before using the meter, taking special care regarding any
WARNING or IMPORTANT notices. The following safe practices and proper operating
procedures should be followed when using any multimeter:
• Inspect the test leads for insulation damage or exposed metal. Damaged leads
should be replaced.
• Select the proper function and range for your measurement.
• Avoid severe shocks and do not drop the multimeter.
• Do not allow the meter to be used if it is damaged or if its safety is impaired.
• WARNING: TO AVOID ELECTRIC SHOCK, USE CAUTION WHEN WORKING ABOVE
40V DC OR 25V AC RMS. SUCH VOLTAGES POSE A SHOCK HAZARD.
• Electrically disconnect the live, or hot, test lead before disconnecting the
common test lead.
• Follow all equipment safety procedures. Disconnect the input power and
discharge all high-voltage capacitors through a protective impedance before
testing in Ωand with the multimeter.
• Avoid working alone.
• When making a current measurement, turn the power off before connecting
the multimeter in the circuit. Overloading a current shunt will cause excessive heat.
• When measuring transformer secondary or motor’ winding current, check the
multimeter fuses first.
• When testing circuits take extra care not to touch any bare metal including the
ends of the test probes.
• The use of makeshift fuses and the short-circuiting of fuse holders is prohibited.
• Whenever it is likely that the protection has been impaired, the meter shall be
made inoperative and be secured against any unintended operation.
• Never attempt to measure a voltage or current higher than the maximum rating
of the meter.
Continuity/Diode Measurement
1. Connect the BLACk?test lead to the COM jack and the RED test lead to
the V/Ω/F jack.
2. Set the FUNCTION switch to the Position and push the Button to select
continuity or diode test mode.
3. In continuity testing, if the resistance is less than 20Ω, the built in buzzer will sound.
4. If testing diodes, connect the test leads across the diode under test, (red to the
anode). Display shows the approx forward voltage of this diode.
Transistor hFE Test
1. Set the FUNCTION switch to the hFE range.
2. Determine whether the transistor is NPN or PNP and locate the Emitter, Base and
Collector leads. Insert the leads into the proper holes in the socket on the front
panel.
3. Display will read approx. hFE value at the test condition/Base Current l0µA
VCE 3.2V
Measuring Range Control Button
AC/DC voltage AC/DC current ranges (µA and mA only),
Resistance and Frequency, can be set manually using this feature as follows.
1. Switching power ON, or changing FUNCTION, will set the Measuring Range to
automatic mode.
2. To select “Manual”, press range button (1) once, briefly. The letters “R-H” will
appear on the LED.
By pressing range button (1) again, briefly, (less than 1 sec), the range will change as
seen by the decimal point on the scale, moving to indicate xl00 xl000 etc. Pressing
the same button for approx 3 seconds, will return to “auto” mode.
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FEATURES
• Push button ON/OFF power switch.
• Single 13 position rotary switch for FUNCTION selection.
• Auto-Ranging.
• Data Hold function
• Automatic over-range indication, with “OL” being displayed on the display.
• Automatic reverse polarity indication on DC ranges.
• All ranges fully protected.
• DC Voltage measurement 100µV to 1000V
• AC Voltage measurement 1mV to 750V rms
• DC current measurement 0.1µA to 10A
• AC current measurement 0.1µA to 10A
• Resistance measurement 0.1Ωto 32.6MΩ.
• Capacitance measurements 0.1nF to 32.6µF.
• Transistor hFE test with l0µA base current.
• Frequency Range from 10Hz to 200kHz
• Low Battery indication with + - being displayed on LCD
• Holster with 2 position stand, and test lead holders to ease the taking of
readings whilst holding the meter.
SPECIFICATIONS
DC Voltage - (Auto ranging) Accuracies are ± (% reading + No. of digits)
Range Accuracy Resolution
326mV ±0.5% of rdg ± 2 digits l00µV
3.26V lmV
32.6V ± 0.3% of rdg ± 2 digits l0mV
326V l00mV
1000V +0.5 of rdg ± 2digits lV
Input Impedance: 10MΩMore than l00MΩon 326mV range.
AC Voltage - (Auto ranging)
Range Accuracy Resolution
3.26V lmV
32.6V ± 0.8% of rdg ± 3 digits l0mV
326V l00mV
750V lV
Input Impedance: 10MΩon all ranges. Frequency Range: 40Hz to 1000 Hz
Resistance Measurement
IMPORTANT. When checking-in circuit resistance, ensure the circuit under test has
all power removed and that all capacitors are fully discharged.
1. Connect the BLACK test lead to the COM jack and the RED test lead to
the V/Ω/F jack.
Note: the polarity of the RED test lead is “+”.
2. Set the FUNCTION switch to the position, and connect the test leads across the
resistance to be measured.
Note:
1. The Meter may take a few seconds to become stable for resistance over
3.26M Ω . This is normal for high resistance readings.
2. When the input is not connected, i.e. an open circuit, the figure “OL” will be
displayed for the over range condition.
Capacitance Measurements
IMPORTANT. When checking-in circuit capacitance, ensure the circuit under test
has all power removed and that all capacitors are fully discharged.
1. Connect the BLACK test lead to the COM jack and the RED test lead to the
mA/CX jack
2. Set the function switch to nF or µE position to be used.
Note that the polarity of the red lead is “+”.
3. Connect test leads across the capacitor to be measured, ensuring correct
polarity is observed.
Note: The range control mode in capacitance measurement is manual ranging,
and only two ranges are provided - 326nF and 32.6 µ F.
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DC Current - (Auto ranging for µA and mA)
Range Accuracy Resolution
326µA 0.lµA
3260µA 1 µA
32.6mA l0µA
326mA 0.lmA
10A ±2% of rdg ± 5 digits 10mA
Overload Protection: 0.3A/250V and 10A/250V fuse
AC Current - (Auto ranging for pA and mA)
Range Accuracy Resolution
326µA 0.lµA
3260µA 1µA
32.6mA l0µA
326mA 0.lmA
10A ±3% of rdg ± 7digits l0mA
Overload Protection: 0.3A/250V and 10A/250V fuse.
Resistance - (Auto ranging)
Range Accuracy Resolution
326Ω±0.8% of rdg ± 3digits 0.1Ω
3.26KΩ1Ω
32.6KΩ± 0.8% of rdg ± 1 digit 10Ω
326KΩ100Ω
3.26MΩ1KΩ
32.6MΩ± 1.2% of rdg ± 2 digits 10KΩ
± 1.2% of rdg ± 3 digits
± 1.5% of rdg ± 5 digits
AC/DC Voltage Measurement
WARNING. Use extreme caution measuring high voltages, and do not attempt to
measure voltages greater than 1000 Volts, as this can damage internal circuitry.
1. Connect the BLACK test lead to the COM jack and the RED test lead to
the V/Ω/F jack.
2. Set FUNCTION switch to V~ or V range to be used and connect test leads across
source or load.
Reverse polarity is indicated by a “—” sign being displayed in front of the reading.
AC/DC Current Measurement
WARNING: Do not attempt to measure a current in excess of 10 Amps
1. Connect the BLACK test lead to the COM jack and the RED test lead to the
mA/CX jack for a maximum of 300mA. For a. maximum of 10A move the red
test lead to the 10A jack.
2. Set the FUNCTION switch to the µA mA or A range to be used, and push /~
button (3) to select D/C A or A/C A measuring mode.
3. Connect the test leads in series with the load in which the current is to be
measured. Reverse polarity is indicated by a “-” sign being displayed in front of
the reading.
4. The maximum input current is 300mA, or 10A depending on the jack used.
Excessive current will blow the fuse which must be replaced. The fuse rating should
be 300mA and 10A and no more to prevent damageto the internal circuitry.
OPERATION
1. Check the 9-volt battery by setting the ON-OFF switch to ON, if the battery is
weak, a + - sign will appear on the display. If this does not appear on the
display, proceed as below. See MAINTENANCE if the battery has to be
replaced.
2. The mark, or symbol, next to the test lead jacks, is a warning that the input
voltage or current should not exceed the indicated values, to prevent
damage to internal circuitry.
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Capacitance - (Manual Ranging)
Range Accuracy Resolution
326nF ±3.0% of rdg ± 5digits 0.1nF
32.6µF l0nF
Frequency
Range Accuracy Resolution
32.6kHz ± 1.2% of rdg ± 3 digit 10Hz
200kHz ± 2.5% of rdg ± 3 digit 100Hz
Sensitivity: 200mV up to50k Hz, 1V from 50k Hz to 200k Hz
GENERAL CHARACTERISTICS
Display :3260 counts (3¾ digits). 2/sec update.
Digital Bargraph :32 segments, 12.5/sec update.
Measuring Method :Dual-Speed integration A-D convertor system.
Overrange Indication :Figure “OL’ displayed on the LED.
Temperature Ranges :Operating 0ºC to 40ºC, 32ºF to 104ºF. >75% RH.
:Storage ~10ºC to 50ºC 14ºF, to 122ºF. >80% RH.
Power Supply :One 9V battery (NEDA 1604, 6F22 type or equiv).
Low Battery Indication : + - On left of display.
DESCRIPTION OF PANEL
Nomenclature
1. Range Control Button.
2. Data Hold Button.
3. AC/DC Current or
Selecting Button.
4. Transistor Test Socket.
5. Function Switch.
6. V/Ω/F Input jack.
7. COM Input jack.
8. mA/Cx Input jack.
9. 10A input jack.
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