DMM51FSG
USER’S MANUAL
INTRODUCTION:
Thank you for purchasing General’s DMM51FSG Digital Service Multimeter. It is
a 3-1/2" wide, highly reliable hand-held digital measuring instrument. The meter
uses advanced integrated circuitry with a double integrated A/D converter as its
core and offers full range overload protection. The DMM51FSG can measure the
following: DC current, AC current, DC Voltage, AC Voltage, Resistance, Diodes and
Continuity, which makes it an ideal tool for HVAC users.
Please read and follow the manual carefully.
Digital Service
Multimeter
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SAFETY RULES:
• The DMM51FSG complies with IEC 1010-1 CAT I 1000V, CAT II 600V and CAT III
300V overvoltage standards. Use the meter only as specified in this manual,
otherwise the protection provided by the meter may be impaired.
• CAT I - For signal level, telecommunication, electronic with small transient over
voltage.
• CAT II - For local level, appliances, main wall outlets, portable equipment.
• The meter is designed to withstand the stated maximum voltages. For Safety
reasons,do not exceed the maximum stated voltage ranges.
• Do not operate the meter before the casing has been closed and screwed safely as
the terminals can carry voltage.
• Make sure the meter is set to the correct range before taking each measurement.
• Before using the meter, please inspect the case and test leads for damaged
insulation or exposed metal.
• Connect the red and black test lead to the correct measuring input jack properly.
• Do not input values over the maximum range of each measurement scale to avoid
damages of the meter.
• Do not turn the rotary function switch during Voltage and Current measurement,
otherwise the meter could be damaged.
• Make sure to use new fuses with proper rating. Do not use incorrect fuses.
• To avoid electric shock or damages, do not apply more than 1000V between the
COM terminals and earth ground .
• Use caution when working with Voltages above 60V (DC) or 30Vrms (AC). These
Voltages pose shock hazard.
• Replace the battery as soon as the battery indicator icon “ ” appears. With a
low battery, the meter might produce false readings that can lead to electric shock
and personal injury.
• Turn off the meter once finished measuring. Take out the battery, when the meter
will not be used for long period.
• Do not operate the meter under adverse environmental conditions such as
excessive humidity.
• To avoid damage and dangerous operation, do not alter or change the circuit.
• To clean, periodically wipe the case with a damp cloth and mild detergent. Do not
use abrasives or solvents.
• International Electrical Symbols:
Low Battery Earth Ground
Safety Rules Double Insulated
AC Diode
Dangerous Voltages Buzzer
DC Fuse
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FEATURES:
33 RANGES, 8 FUNCTIONS:
• Liquid Crystal Display, digit height is 27mm
• Overload display
• Maximum display 1999 (3-1/2 digit)
• Full range overload protection
• Temperature:
Operating: 32° to 104°F (0° to 40°C)
Storing: 14° to 122°F (-10° to 50°C)
• Altitude:
Operating: 2000m
Storing: 10000m.
• Relative Humidity:
Max. relative humidity 80% for temperature up to 88ºF (31°C) decreasing
linearly to 50% relative humidity at 104ºF (40°C)
• Low Battery display “ ”
• Strap for easy carry
• Tilt stand with three angles
• Dimension: 7.5 x 3.5 x 1.3" (190 x 88 x 34mm)
• Weight:
Meter only (excluding test leads), 9.5oz (270g) approximately
Meter, holster and tilt stand,19.4oz (550g) approximately
SPECIFICATIONS:
Accuracy is specified for one year after calibration, at operating temperatures 23°C,
+/- 5°C, with relative humidity at < 75%.
Accuracy specifications take the form of: +/- (a% readings +digits)
B-1 DIRECT CURRENT VOLTAGE (DC VOLTAGE)
Range Resolution Accuracy
DMM51FSG
200mV 100V
2V 1mV
20V 10mV
200V 100mV
1000V 1V ± (0.8% rdg + 2 digits)
INPUT IMPEDANCE: All ranges are 10MΩ.
OVERLOAD PROTECTION: 200mV is 250VDC or AC RMS. All other ranges is
750Vrms or 1000Vp-p.
± (0.5% rdg + 1 digits)
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B-2 ALTERNATING CURRENT VOLTAGE (AC VOLTAGE)
Range Resolution Accuracy
DMM51FSG
200mV 100V ± (1.2% rdg + 3 digits)
2V 1mV
20V 10mV ± (0.8% rdg + 3 digits)
200V 100mV
750V 1V ± (1.2% rdg + 3 digits)
INPUT IMPEDANCE: All ranges are 10MΩ.
FREQUENCY: 40Hz-400Hz.
OVERLOAD PROTECTION: 200mV is 250VDC or AC RMS.
All other ranges is 750Vrms or 1000Vp-p.
DISPLAY: Average Value (RMS of Sine Wave).
B-3 DIRECT CURRENT CURRENT (DC CURRENT)
Range Resolution Accuracy
DMM51FSG
20A 0.01A ± (2% rdg +5 digits)
200A 0.1 A ± (0.8%rdg +1 digit)
2mA 1A
± (0.8% rdg +1 digit)
20mA 10A
200mA 100A ± (1.5% rdg +1 digit)
2A 1mA ± (1.5%rdg +1 digit)
10A 10mA ± (2%rdg +5 digits)
OVERLOAD PROTECTION: 2A/250V fuse (below 2A range) and 10A/250V fuse
(10A range).
MAX CURRENT INPUT: 10A
MEASURING VOLTAGE DROP: Full range is 200mV.
B-4 ALTERNATING CURRENT CURRENT (AC CURRENT)
Range Resolution Accuracy
DMM51FSG
200A 0.1A ± (1.8% rdg +3 digits)
2mA 1A ± (1% rdg +3 digits)
20mA 10 A ± (1% rdg +3 digits)
200mA 100A ± (1.8% rdg +3 digits)
2A 1mA ± (1.8% rdg +3 digits)
10A 10mA ± (3% rdg +7 digits)
OVERLOAD PROTECTION: 2A/250V fuse (below 2A range) and 10A/250V fuse
(10A range).
MAX CURRENT INPUT: 10A
MEASURING VOLTAGE DROP: Full range is 200mV.
DISPLAY: Average Value (RMS of Sine Wave ).
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B-5 RESISTANCE
Range Resolution Accuracy
DMM51FSG
200Ω 0.1Ω ± (0.8% rdg + 3 digits)
2KΩ 1Ω
20KΩ 10Ω
200KΩ 100Ω
± (0.8% rdg + 1 digit)
2MΩ 1KΩ
20MΩ 10KΩ ±(1% rdg + 2 digits)
200MΩ 100KΩ ± [ 5% (rdg-10 + 10 digits) ]
VOLTAGE AT OPEN CIRCUIT: ≤700mV (200MΩ range, open circuit voltage
around 3V).
OVERLOAD PROTECTION: All ranges 250VDC or AC RMS.
CAUTION: At 200MΩ range, as test lead is short circuit the LCD display 10 digits
is normal, deduct the 10 digits from the measured reading during
measuring.
B-6 DIODE TEST AND CONTINUITY BEEPER
Range Comment Measuring Condition
Display diode forward- Forward DC current abt 1mA
voltage near value, Backward DC voltage abt 2.8V
Unit “mV”
Beeper sounds if Voltage at open circuit
Continuity Resistance abt 2.8V
≤70Ω. Display near value
Unit “Ω”
OVERLOAD PROTECTION: 250V DC or AC RMS.
B-7 TRANSISTOR hFE TEST
Range Comment Measuring Condition
hFE Can measure NPN Basic polarity current abt
or PNP transistor 10A,Vce abt 2.8V
hFE Range: 0-1000
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TAKING MEASUREMENTS:
CAUTION:
1. If there is no display or “ ” is shown on the LCD when the meter is switched on,
replace the battery ASAP.
2. Never exceed the maximum input voltage or current limits shown besides the input
jacks “ ”, otherwise the meter will be damaged and this is dangerous to life.
3. Turn the rotary switch to proper range before operating.
1. On/Off Switch
2. Liquid Crystal Display
3. Rotary switch
4. Transistor jack
5. Input jack
C-1 MEASURING DC VOLTAGE
1) Connect the black test lead to “COM” jack and red test lead to “V” jack.
2) Set the rotary switch to “V ”.
3) Connect the test leads across with the object to be measured. LCD appears the
measuring value and also the polarity of the red test lead.
CAUTION
1) If magnitude of the voltage being measured is unknown, always start with the
highest range and reduce until satisfactory reading is obtained.
2) If “1” is shown on the LCD, which means the meter is overloaded, then set the
measuring range to a higher range.
3) “ ” means never to exceed the maximum input limits of 1000V, otherwise
internal circuit of the meter will be damaged.
4) Take extra care of voltage leakage when measuring high voltage.
C-2 MEASURING AC VOLTAGE
1) Connect the black test lead to “COM” jack and red test lead to “V” jack.
2) Set the rotary switch to “V~”.
3) Connect the test leads across with the object to be measured.
CAUTION
1) Refer to “DC Voltage Caution” 1, 2, 4.
2) “ ” means never exceed the maximum input limit 750V, otherwise internal
circuit of the meter will be damaged.
1.
2.
3.
4.
5.
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C-3 MEASURING DC CURRENT
1) Connect the black test lead to “COM” jack. When measuring 2A or below,
connect the red test lead to “A” jack. When measuring 10A or below, connect
the red test lead to “10A” jack.
2) Set the rotary switch to “A ”.
3) Connect the test leads in series with the object to be measured, the LCD
display the measuring value and polarity of red test lead.
CAUTION
1) If magnitude of the current is unknown, always start with the highest range
and reduce until satisfactory reading is obtained.
2) If “1” is shown on the LCD, which means the meter is overloaded, then set the
measuring range to higher.
C-4 MEASURING AC CURRENT
1) Connect the black test lead to “COM” jack. When measuring 2A or below,
connect the red test lead to “A” jack. When measuring 10A, connect the red
test lead to “10A” jack.
2) Set the rotary switch to“A~”.
3) Connect the test leads in series with the object to be measured.
CAUTION
1) Please refer to “DC Current Caution” 1, 2.
C-5 MEASURING RESISTANCE
1) Connect the black test lead to “COM” jack and red test lead “Ω” jack.
2) Set rotary switch to“Ω”.
3) Connect the test leads across with the object to be measured.
CAUTION
1) If “1” is shown on the LCD, which means the meter is overloaded, then set a
higher measuring range. If resistance is above 1MΩ, the reading will only be
steady after a few seconds which is normal for measuring high value of
resistance.
2) “1” is displayed when open circuit or no input.
3) Make sure all objects, circuit and components to be measured are without
voltage.
4) 200MΩ short circuit has 10 digits which need to be deducted after the reading
when making measurement. For example, when measuring 100MΩ, it displays
101.0, 10 digits need to be deducted.
C-6 MEASURING DIODE AND CONTINUITY BEEPER
1) Connect the black test lead to “COM” jack and red test lead to “V” jack.
2) Set the rotary switch to “ ”
3) Connect the test lead across with the object being measured. LCD appears the
measuring value.
4) Connect the test lead to two ends of the object being measured, the beeper
sounds if the resistant value between the two ends is less than 70Ω.
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C-7 MEASURING TRANSISTOR hFE
1) Set rotary switch to “hFE”.
2) Identify NPN or PNP, connect objects to the correspondent transistor jack.
3) LCD displays measuring value.
4) Measuring condition: Ib ≈ 10A, Vce ≈ 2.8V
MAINTENANCE:
The DMM51FSG is a highly precise electrical testing instrument, do not attempt to
change the circuit of your meter on your own. Take a note of the following points:
1) Do not input to DC Voltage above 1000V or AC above 750V RMS.
2) Do not input Voltage when the rotary switch is in Current Range, Ω and .
3) Do not operate the meter if battery is not inside the meter or the casing is not
securely screwed together.
4) Disconnect the test leads and power off the meter before replacing the battery
and fuses.
5) To replace the battery, loosen the screws on the back cover and open the case.
Replace the exhausted battery with a new one of the same type.
The fuse rarely needs to be replaced and is usually blown as a result of
operator error. To replace the fuse, open the case as above and replace the
blown fuse with the ratings specified: F 2A/250V or F10A/250V.
ACCESSORIES:
1) User’s manual 2) Test leads 3) Holster
USING HOLSTER:
Three different ways to use holster:
1) Set holster parallel on the table, do not open the tilt stand (see Figure 1).
2) Set holster in a small angle on the table, tilt it up by the first part of tilt stand
(see Figure 2)
3) Set holster in a large angle on the table, tilt it up by all two parts of tilt stand
(see Figure 3).
USING STRAP:
1) Feed the front end of the strap through the
round metal loop of the meter
(see part 1 of the diagram).
2) Put the bottom end of the strap through the
front and pull it through
(see part 2 of the diagram).
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