Operating Instructions

Model MM44

Digital Multimeter

SAFETY INFORMATION

The instrument meets the requirements for double insulation to BS EN 61010-1 at 600V Installation

Category III. Installation Category III (distribution level) relates to transient overvoltage likely to be found in fixed installation wiring.

The following safety information must be observed to ensure maximum personal safety during the operation of this meter:

Do not use the meter if the meter or test leads look damaged, or if you suspect that the meter is not operating properly.

Never ground yourself when taking electrical measurements. Do not touch exposed metal pipes, outlets, fixtures, etc, which might be at ground potential. Keep your body isolated from ground by using dry clothing, rubber shoes, rubber mats, or any insulating material.

Turn off power to the circuit under test before cutting, unsoldering, or breaking the circuit. Small amounts of current could be dangerous.

Use caution when working above 30V AC rms or

60V DC. Such voltages pose a shock hazard.

When using the probes, keep your fingers behind the finger guards on the probes.

MM44 REV3 7/05

NOTE

This instrument is only to be used by a suitably trained and competent person.

The symbols used on this instrument are: z

Caution, risk of electric shock

Caution, refer to accompanying documents

Equipment protected throughout by Double Insulation (Class II)

~

Alternating current

Direct current

Ground

Measuring voltage which exceeds the limits of the multimeter may damage the meter and expose the operator to a shock hazard. Always recognise the meter voltage limits as stated on the front of the meter.

HIGH ENERGY SYSTEMS

GS38 advises fused test leads to be used when working on high energy systems. Suitable leads are

Martindale TL55.

SPECIFICATIONS

Display: 3½ digit liquid crystal display (LCD) with a maximum reading of 1999.

Polarity: Automatic, positive implied, negative polarity indication.

Overrange: (OL) or (-OL) is displayed.

Zero: automatic.

Low Battery Indication: The is displayed when the battery voltage drops below the operating level.

Measurement rate: 2.5 times per second, nominal.

Operating environment: 0°C to 50°C at < 70% R.H.

Storage temperature: -20°C to 60°C, 0 to 80% R.H.

with battery removed from meter.

Accuracy: Stated accuracy at 23°C ± 5°C, < 75% R.H.

Battery life: 200 hours typical with carbon-zinc.

Battery: Single standard 9-volt battery, NEDA 1604,

JIS 006P, IEC 6F22, PP3.

Dimensions: 147mm (H)x 70mm (W)x 39mm (D).

Weight: Approx. 345g including holster.

Accessories: One pair test lead, One spare fuse, 9V battery (installed) and Operating Instructions.

D C VOLTS

Ranges: 200mV, 2V, 20V, 200V, 600V

Resolution: 100µV

Accuracy: ± (0.8% rdg + 1 dgt)

Input impedance: 10M Ω

Overload protection: 600VDC or AC rms

AC VOLTS: (50Hz - 500Hz)

Ranges: 200mV, 2V, 20V, 200V, 600V

Resolution: 100µ V

Accuracy: ± (1.5% rdg + 3 dgts) on 200mV to 20V ranges

± (2.0% rdg + 3 dgts) on 200V to 600V ranges

Input impedance: 10M Ω

Overload protection: 600V DC or AC rms

DC CURRENT

Ranges: 20mA, 200mA, 10A

Accuracy: ± (1.0% rdg + 1 dgt) on 20mA to 200mA ranges

± (3.5% rdg + 4 dgts) on 10A range

Input protection: 0.5A/250V fast blow ceramic fuse

10A/600V fast blow ceramic fuse

AC CURRENT: (50Hz - 500Hz)

Ranges: 20mA, 200mA, 10A

Accuracy: ± (2.0% rdg + 4 dgts) on 20mA to 200mA ranges

± (3.5% rdg + 4 dgts) on 10A range

Input protection: 0.5A/250V fast blow ceramic fuse

10A/600V fast blow ceramic fuse

RESISTANCE

Ranges: 200 Ω , 2k Ω , 20k Ω , 200k Ω , 2000k Ω , 20M Ω ,

2000M Ω

Accuracy: ± (1.0% rdg + 4 dgts) on 200 Ω ranges to

2000k Ω

± (2.0% rdg + 4 dgts) on 20M Ω range

± [(5.0% rdg - 10 dgts) + 10 dgts] on 2000M Ω range

Open Circuit volts: 0.3V DC

Overload Protection: 500V DC or AC rms

CONTINUITY

Audible indication: Less than 100 Ω

Overload protection: 500V DC or AC rms

DIODE TEST

Test current: 0.8mA ± 0.3mA

Accuracy: ± (3.0% rdg + 1 dgt)

Open circuit volts: 3.0V DC typical

Overload protection: 500V DC or AC rms

CAPACITANCE

Ranges: 2nF, 20nF, 200nF, 2µF, 20µF

Accuracy: ± (4.0% rdg + 10 dgts) on all ranges

Test frequency: 400Hz

TRANSISTOR hFE

Ranges: 0 - 1000

Base current: 10µA dc approx. (Vce = 3.0V DC)

FREQUENCY (Autoranging)

Ranges: 2kHz, 20kHz, 200kHz, 2MHz, 15MHz

Accuracy: ± (0.5% rdg + 2 dgts) on all ranges

Sensitivity: 1V RMS min.

Duty: <40% and > 60%

Overload protection: 500V DC or AC rms

LOGIC TEST

Threshold: Logic Hi (2.8 ± 0.8V)

Logic Lo (0.8 ± 0.5V)

Overload protection: 500V DC or AC rms

INPUT WARNING BEEPER

Incorrect test lead placement will cause this meter to issue a warning beeper sound. The warning beeper indicates that a test lead is plugged into a current input socket and the Function/Range switch is not set to a current range. For instance, if the red test lead is plugged into the mA current socket and the meter switch is set to 200V, the warning beeper will sound. Another safety feature to protect the meter and you.

OPERATION

Before taking any measurements, read the Safety

Information Section. Always examine the instrument for damage, contamination (excessive dirt, grease, etc.) and defects. If any abnormal conditions exist do not attempt to make any measurements.

MM44 REV3 7/05

Voltage Measurements

1. Connect the red test lead to the "V Ω " socket and the black test lead to the "COM" socket.

2. Set the Function/Range switch to the desired voltage range and slide the "AC/DC" selector switch to the desired voltage type. If magnitude of voltage is not known, set switch to the highest range and reduce until a satisfactory reading is obtained.

3. Connect the test leads to the device or circuit being measured.

4. For DC, a (-) is displayed for negative polarity; positive polarity is implied.

Current Measurements

1. Set the Function/Range switch to the desired current range and slide the "AC/DC" selector switch to the desired current type.

2. For current measurements less than 200mA, connect the red test lead to the mA socket and the black test lead to the COM socket.

3. For current measurements of 200mA or greater, connect the red test lead to the 10A socket and the black test lead to the COM socket.

4. Remove power from the circuit under test and open the normal circuit path where the measurement is to be taken. Connect the meter IN SERIES with the circuit.

Resistance and Continuity

1. Set in the Function/Range switch to the desired resistance range or continuity position.

2. Remove power from the equipment under test.

3. Connect the red test lead to the "V Ω " socket and the black test lead to the "COM" socket.

4. Touch the probes to the test points. In ohms, the value indicated in the display is the measured value of resistance. In continuity test, the beeper sounds continuously, if the resistance is less than 100 Ω .

Note when using 2000M Ω Range

The 2000M Ω range has a fixed 10-count offset in the reading. When the test leads are shorted together in this range, the meter will display 010.

This residual reading must be subtracted from the reading. For example, when measuring 1100M Ω on the 2000M Ω range, the display will read 1110, from which the 10 residual is subtracted to obtain the actual resistance of 1100M Ω .

Diode Tests

1. Connect the red test lead to the "V Ω " socket and the black test lead to the "COM" socket.

2. Set the Function/Range switch to the " " position.

3. Turn off power to the circuit under test.

4. Touch probes to the diode. A forward-voltage drop is about 0.6V (typical for a silicon diode).

5. Reverse probes. If the diode is good, "OL" is displayed. If the diode is shorted, "000" or another number is displayed.

6. If the diode is open, "OL" is displayed in both directions.

7. If the junction is measured in a circuit and a low reading is obtained with both lead connections, the junction may be shunted by a resistance of a less than 1k Ω . In this case the diode must be disconnected from the circuit for the accurate testing.

Transistor Gain Measurements

1. Set the Function/Range switch to the desired hFE range (PNP or NPN type transistor).

2. Never apply an external voltage to the hFE sockets.

Damage to the meter may result.

3. Plug the transistor directly into the hFE sockets.

The sockets are labelled E, B and C for emitter, base and collector.

4. Read the transistor hFE directly from the display.

Capacitance Measurements

1. Set the Function/Range switch to the desired Cx

(capacitance) range.

2. Never apply an external voltage to the Cx sockets.

Damage may result.

3. Insert the capacitor leads directly into the Cx sockets.

4. Read the capacitance directly from the display.

Logic Measurements

1. Set the Function/Range switch to the LOGIC position.

2. Connect the red test lead to the "V Ω " socket and the black test lead to the "COM" socket.

3. Connect the red test lead to the test point and the black lead to the common buss of the logic circuit.

4. A " " on the display indicates TTL logic high and a " " indicates a TTL logic low. Both indicators are on when the point of measurement is toggling high and low.

Frequency Measurements

1. Set the Function/Range switch to the kHz position.

2. Connect the red test lead to the "V Ω " socket and the black test lead to the "COM" socket.

3. Connect the test leads to the point of measurement and read the frequency from the display.

MAINTENANCE

W

ARNING

Remove test leads before changing battery or fuse

Battery Replacement

Power is supplied by a 9 volt "transistor" battery.

(NEDA 1604, IEC 6F22, PP3). The appears on the LCD display when replacement is needed. To replace the battery, remove the three screws from the back of the meter and lift off the front case. Remove the battery from case bottom.

Fuse Replacement

If no current measurements are possible, check for a blown overload protection fuse. There are two fuses; F1 for the mA socket and F2 for the 10A socket. For access to fuses, remove the three screws from the back of the meter and lift off the front case. Replace F1 only with the original type 0.5A/250V, ceramic, fast acting fuse. Replace F2 only with the original type

10A/600V ceramic, fast acting fuse. The use of other fuses may cause damage to the meter, invalidate the warranty and impair the safety of the user. Domestic

‘Plug Top’ fuses should not be used.

Instrument Repairs and Spare Parts

Apart from the battery and fuses, there are no user serviceable parts inside. If you suspect that the meter is not operating properly, please check fuses, battery and leads.

If the meter is still suspected of being faulty please contact:

Martindale Electric Co Ltd,

Metrohm House, Imperial Park, Imperial

Way, Watford, Hertfordshire, WD24 4PP, UK

Tel: 01923 441717 Fax: 01923 446900

Accessories

F1 - 20x5mm 500mA 250V Ceramic -

Ref: FUSE500250 (Pack of 3)

F2 - 1x1/4” 10A 600V Ceramic - Ref: FUSE10600

(Pack of 3)

Fused test leads to GS38 specification - Ref: TL55

Soft foam lined carry case - Ref: TC55