Mastech MS8240B User manual

MS8240B
Digital Multimeter
FUNC HOLD
MAX
FUSED FUSED
Digital Multimeter
Operating Instruction
MS8240B

1. Introduction
CONTENTS
5. Measurement Operation
5.1 DC & AC Voltage Measurement
5.2 Resistance Measurement
5.3 Diode/Continuity Check
5.4
5.5 Transistor Check
5.6 Frequency Measurement
5.7 DC/AC mA/10A Measurement
5.8 Inductance Measurement
5.9 Temperature Measurement
Capacitance Measurement
.............................................1
.........................10
....................10
2. Safety note
3. Product Overview
...............................................1
....................................3
3.1 Meter Illustration
3.2 Functional Push Button
3.3 Display Indicators
..................................3
.........................4
4. Specification............................................5
4.1 General Feature
4.2 Electrical Specification
....................................5
..........................6
.......................11
..................12
.................................13
.....................14
.............15
....................16
..................16
6. Maintenance
...........................................19
6.1 Replacing The Battery
6.2 Fuse Replacement
6.3 Cleaning and Decontamination
...........................19
..............................19
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01
1. Introduction
This Meter is a handheld and battery operated Digital
Multi Meter(DMM) with multi function. This Meter is
designed to meet IEC-61010-1 CAT III 1000V over
voltage category and double insulation. The entire
outer surface of the case has been formed with thermo
plastic elastomer,giving the main body, though
downsized, high resistance against the shock of a drop.
This operating instruction covers information on safety
and caution. Please read relevant information carefully
and observe all the warnings and note strictly. The
DMM as general measurement tool and widely used in
the school, laboratory, factory etcsocial field.
2. Safety Note
To avoid possible electric shock or personal injury and
to avoid possible damage to the meter or to the
equipment under test, adhere to the following rule:
Warning
..................................4
............10
• Do not apply more than the rated voltage of marked
on the meter
• Do not apply voltage between COM and OHM
terminal, in the resistance measuring state.
• Do not measure current with test lead inserted into
voltage or OHM terminal.
• Do not expose the instrument to the direct sun light,
extreme temperature and humidity or dew full.
• Inspect the test lead for damaged insulation or
exposed metal.
• Before measuring current, check the Meter's fuses
and turn off power to the circuit before connecting
the meter to the circuit.

FUNC HOLD
MAX
FUSED FUSED
0302
Dangerous voltage Grounding
AC
(Alternating Current)
Double insulation
DC (Direct Current)
Fuse
3. Explanation of Controls and Indicators
3.1 Meter Illustration
FRONT PANEL
1
2
3
4
5
6
8
7
11
10
9
• Disconnect circuit power and discharge all high
voltage capacitors before testing continuity, diode,
resistance, capacitance or current.
Note international Electrical Symbol.
AC or DC
Warning see
explain in manual
(1) LCD Display
(2) “MAX” push button
(3) “HOLD” push button
(4) Rotary Switch (Knob)
(5) “V. Ω. Hz” Input terminal
(6) “COM” terminal
(7) “μA.mA.°C.Cx.Lx.hFE”Input terminal
(8) “10A” input terminal
(9) Power switch(ON.OFF)
(10) “FUNC” push button
(11) “BKLIT” push button

04 05
3.2 Functional Push Button
“FUNC” key is the function select key that
acts with trigger. Use the key as switch of
DC/AC voltage,DC/AC current ,
Resistance/Continuity and °C/°F.
Press “HOLD” to enter and exit the hold
mode in any mode. That act with trigger.
This key is act with trigger. Press this key
once, the maximum value is holding (Will
displays 'MAX' symbol in the LCD).
After pressing the key, A/D will keep
working, and the display value are always
up dated and kept the maximum value.
(The actual gained value is not the
peak value.).
This key is used to control Backlight.
This key is act with trigger. When press
the key, will enable Backlight for 15 sec.
Press the key again within 15 sec,
Backlight will disable.
ON/OFF Lock type Power Switch.
FUNC
HOLD
MAX/MIN
Push button Function
Back light
*
3.3 Display Indicators
FIG 2 LCD
Number Indicator Meaning
1
2
3
4
5
6
7
8
10
11
12
13
14
MAX
HOLD
MkΩ
°C/°F The unit of temperature ( °C:
Centigrade; °F: Fahrenheit)
9µmVA uV mV V is unit of voltage
uA mA A is unit of current
Indicate negative reading
Capacitance Indicator
Cx
Lx
mH/H
nµmF
Inductance Indicator
Inductance Units
Capacitance Units
Ω KΩ MΩ is unit of resistance
Low battery indicator
Data hold
Maximum value
Diode
AC voltage or current
DC voltage or current

06 07
4. Technical Specifications
4.1 General Specifications
• Manual ranging DMM , that full scale is 1999 counts
• Display : 3 1/2 digit LCD display.
• Over load protection: Used the PTC protection
circuit for Resistance, capacitance And frequency
measurement.
• DATA HOLD function
• MAX value measurement function
• Back Light
• Low battery indication
• Auto Power- OFF.
• Operating temperature & Humidity: 0 ~ 40°C
(32~104°F) & < 80% RH
• Storage temperature & Humidity: -10 ~ 50°C
(14~122°F) & <70%RH
• Power Supply: 1.5V Battery(AA Type)×4
• Safety Class: IEC-61010-1, 1000V CAT III,
600V CAT IV.
• Dimension (L×W×H) & Weight:
205 mm×102 mm×58mm, Approx. 390g.
4.2 Electrical Specification( at 23±5 <75% RH)°C
4.2.1 DC voltage
Range Resolution Accuracy
200mV 0.1mV
2V
20V
200V
1000V
1mV
10mV
100mV
1V
±(0.5% rdg + 2dgt)
* Input impedance: 10MΩ
* Over load protection: 250V DC/AC(rms)
at 200mV Range.
* Max input voltage: 1000VDC
4.2.2 AC voltage
Range Resolution Accuracy
200mV 0.1mV
2V
20V
200V
1000V
1mV
10mV
100mV
1V
±(0.8% rdg + 3dgt)
±(1.0% rdg + 5dgt)
* Input impedance: 10MΩ
* Over load protection: 250V DC/AC(rms)
at 200mV Range.
* Frequency response: 40~400Hz
* Average rectifier type.
* Max input voltage: 750V AC rms
4.2.3 Resistance
Range Resolution Accuracy
200Ω0.1Ω
2kΩ
20kΩ
200kΩ
2MΩ
20MΩ
0.001kΩ
0.01kΩ
0.1kΩ
0.001MΩ
0.01MΩ
±(0.8% rdg + 3dgt)
±(1.5% rdg + 5dgt)
* Over load protection: 250V DC/ AC rms

08 09
4.2.4 Diode
Range Resolution Function
0.001V Will display the forward
drop voltage.
* Over load protection: 250V DC/ AC rms
4.2.5 Continuity
Range Function
If measured resistance less than 30Ω,
will buzzer is sounded.
* Over load protection: 250V DC/ AC rms
4.2.6 DC Current
Range Resolution Accuracy
2mA
20.00mA
200.0mA
10.00A
1µA
0.01mA
0.1mA
0.01A
(1.0% rdg + 3dgt)
(2.0% rdg + 3dgt)
* Over protection: use the fuse(F250mA/1KV)
at mA range, and use the fuse(F10A/1KV) at 10A range.
* Max input current: 200mA at 'mA' jack
and 10A at '10A' jack.
4.2.7 AC Current
Range Resolution Accuracy
2mA
20mA
200.0mA
10.00A
1µA
0.01mA
0.1mA
0.01A
(1.5% rdg + 5dgt)
(3.0% rdg + 10dgt)
* Over protection:use the fuse(F250mA/1KV) at mA
range, and use the fuse(F10A/1KV) at 10A range.
* Max input current::200mA at 'mA' jack and
10A at '10A' jack.
* Frequency response:40 ~ 400Hz
4.2.8 Temperature
You can selecting Centi-degree[°C] or Fahrenheit
[°F] by “FUNC” key.
Range -20°C ~ 1000°C
-20°C~0°C
1°C
400°C~1000°C
* Over load protection: use the fuse[ F250mA/1KV].
(2.0% rdg + 3dgt)
Resolution
0°C~400°C
Fahrenheit Temperature [°F]
Accuracy (1.0% rdg + 3dgt)
(5.0% rdg + 4dgt)
0°F~1800°F
Range
-0°F~50°F
1°F
750°F~1800°F (2.0% rdg + 3dgt)
Resolution
50°F~750°F
Accuracy (1.0% rdg + 3dgt)
(5.0% rdg + 4dgt)

10 11
4.2.9 Capacitance
Range Resolution Accuracy
2nF 0.001nF
±(4.0%rdg +5dgt)
20nF
200nF
2µF
20µF
0.01nF
0.1nF
0.001nF
0.01µF
* Over load protection: use the fuse[F250mA/1KV]
200µF 0.1µF ±(5.0%rdg +10dgt)
4.2.10 hFE
Range Function
hFE: 1~1000
hFE
* Over load protection: use the fuse [F250mA/1KV ]
4.2.11 Frequency
* Sensitivity: 200mV -5V AC rms
* Over load protection: 250V DC/AC rms
Range Resolution Accuracy
20kHZ 1HZ ±(1.5%rdg+5dgt)
4.2.12 Inductance
Range Resolution Accuracy
2mH 0.001mH ±(4.0%rdg +8dgt)
20mH
200mH
2H
0.01mH
0.1mH
1mH
20H 10mH
±(4.0%rdg +3dgt)
±(4.0%rdg +3dgt)
±(4.0%rdg +3dgt)
±(4.0%rdg +5dgt)
• Over load protection: use the fuse [ F250mA/1KV]
To avoid harms to you or damage to the
meter from electric shock. Please do not
attempt to measure voltage higher than
DC 1000V/AC 700Vrms although readings
may be obtained.
5.1 DC & AC Voltage Measurement
5. Measurement Operation
The DC voltage ranges are 200.0mV, 2.000V, 20.00V ,
200.0V and 1000V; and then. The AC voltage ranges
are 200.0mV,2.000V, 20.00V, 200.0V and 750.0V.
To measure DC/AC voltage:
1. Insert the red test lead into the “VΩ” input terminal
and the black test lead into the COM terminal.
2. First time, Default mode is DC measurement mode,
you can select the AC voltage mode by 'FUNC“ key.
3. Set the rotary switch to proper DC/AC mV or V range.
4. Connect the test lead across with the object being
measured. The measured value will be show on the
LCD display.
6. If the “OL” symbol is displayed on the LCD, you
must be set the rotary switch to the higher range.
Note:
In the rang of 200mV in DC/AC and 2V AC, even in the
absence of input or connectivity test leader, there also
have something display on LCD. in this case,
short-circuit "V" and "COM", so that LCD display
back to zero.

12 13
To avoid damage to the Meter or to the
equipment under test, disconnect power
and discharge all high-voltage capacitors
before resistance measurement.
5.2 Resistance Measurement
The resistance range are:200Ω,2.000kΩ,20.00kΩ,
200.0kΩ,2.000MΩ,20.00MΩ.
To measure resistance, connect the meter as follows:
1. Insert the red test lead into the ”VΩ” terminal and
the black test lead into the COM terminal.
2. Set the rotary switch to proper resistance range.
Connect the test lead across with the object being
measured. The measured value will be display
on the LCD.
Note:
The test lead can add 0.1Ω to 0.2Ω of error to
resistance measurement. To obtain precision reading
in low-resistance measurement, that is the range of
200.0Ω, short the input terminal before measuring. In
this time, the contact resistance displayed on the LCD.
You can subtract the contact resistance value from
the measured value.
For high-resistance measurement (>10MΩ), it is
normal taking several second to obtain stable reading.
The LCD display “OL” indicating open-circuit for the
tested resistor or the resistor value is higher than the
maximum range of the meter.
To avoid damage to the Meter or to the
equipment under test, disconnect power
and discharge all high-voltage capacitors
before Diode/Continuity check.
5.3 Diode/Continuity check
To avoid damage to the Meter or to the
equipment under test, disconnect power
and discharge all high-voltage capacitors
before Diode/Continuity check.
1. insert the red test lead into the “VΩ” terminal and the
black test lead into the COM terminal.
2. Set the rotary switch to Ω position.
2. For forward voltage drop reading on any
semiconductor component, place the red test lead
on the component anode and place the black test
lead on the component cathode. The measured
value show on the LCD.
3. Select the continuity check mode by the “FUNC” key.
The buzzer may be sound if the resistance of a circuit
under test is less than 30Ω.
5.3 Capacitance Measurement
1. insert the red test lead into the “VΩ” terminal and the
black test lead into the COM terminal.
2. Set the rotary switch to Ω position.
2. For forward voltage drop reading on any
semiconductor component, place the red test lead
on the component anode and place the black test
lead on the component cathode. The measured
value show on the LCD.
3. Select the continuity check mode by the “FUNC” key.
The buzzer may be sound if the resistance of a circuit
under test is less than 30Ω.

14 15
5.5 Capacitance Measurement
Warning
To avoid damaging meter or device to be measured,
before continuity tests, turn off all circuits to be
tested and discharge all capacitors.
The capacitance measuring range of this meter:
2.000nF, 20.00nF, 200.0nF, 2.000uF and 200.0uF.
Method of measuring capacitance:
1. Rotate switch to the appropriate position.
2. Connect black and red test probe to COM input socket
and V input socket, respectively. (You can also use
the dedicated multifunction test holder to measure
capacitance).
3. Measure the two leads of the capacitor to be tested
with other two ends of test probes and read the
measured value from LCD display.
Note:
When measuring bulk capacitors with this meter,
readings will be stablizee after a few seconds.
When measuring the small capacitor with less than 20nF,
the distributed capacitance (displayed base number)
of the meter and wire should be subtracted.
5.6 Transistor Measurement
Warning
Do not apply any RMS voltage higher than 250V DC
or AC between common end and hFE end.
This prevents electrical shock and/or meter damage.
Method of measuring transistor:
1. Rotate the switch to hFE position.
2. Plug multi-function socket with correct polarity
(the “+” end of multi-function socket is connected with
hFE end, “COM” end is connected with common end).
3. Determine that the transistor is NPN or PNP type,
then insert three pins of transistor, e.b.c, to the
corresponding holes of dedicated multi-functional
socket.
4. Read hFE approximation of transistor to be measured
from LCD display.

16 17
5.7 Frequency Measurement
Warning
Do not measure the frequency of RMS voltage
higher than 250V DC or AC. This prevents electrical
shock and/or meter damage.
Method of measuring frequency:
1. Rotate switch to 20KHZ position.
2. Connect black and red test probe to COM input socket
and HZ input socket, respectively.
3. Measure the frequency value of circuit to be tested
with other two ends of test probes.
4. Read the measured frequency value from LCD display.
Note:
Do not input the voltage over 10V RMS, as accuracy of
readings cannot be guaranteed.
5.8 Current Measurement
Warning
To avoid damage to meter or device, before
measuring current, please check the meter's fuse.
When measuring, use correct input socket, function
selection and measuring range.
When the circuit voltage is over 250V, do not attempt
to measure current on the circuit.
When the test probe is inserted to the current input
socket, don't connect the other end of the test probe
with any circuit in parallel.
DC measuring range of meter:
2.000mA, 20.00mA, 200.0mA and 10.00A;
AC measuring range: 200.00mA and 10A.
Method of measuring current:
1. Turn off the power supply and discharge all high
voltage capacitors on the circuit to be tested.
2. Rotate switch to the appropriate position.
3. Connect the black test probe to the COM input socket.
If the current to be tested is lower than 200mA, connect
the red test probe to the mA input socket. If the
measured current is between the range of 200mA~10A,
the red test probe should be connected to 10A input
socket.
4. Turn off the circuit to be tested. Connect the black test
probe to the low voltage end of disconnected circuit to
be tested and the red test probe is connected to the
other end (high voltage) of disconnected circuit.
5. Connect the power supply to the circuit, then read the
LCD display. If the display shows only “OL”, it means
that the input is out of the selected input range.
Please rotate the switch to a higher measuring range.
6. Turn off the power to the circuit tested. Discharge all
the capacitors, remove the test probes from the meter
and restore the circuit to the original state.
Note:
1. When measuring current, the meter should be
connected in series, instead of in parallel, to avoid the
meter damage and risking personal safety.
2. Lengthy measurements of large currents (>10A) will
affect the display accuracy of the meter. Standard test
time cannot be over 10 seconds in any 3 minute period.
3. During DC measurement, if the test probes are
connected in reversal order to the circuit, the display
will become negative, but the measurement accuracy
of the meter will not be affected.

18 19
6.1 Battery Replacement
6. Maintenance
5.9 Temperature Measurement
Warning
Do not input any voltage higher than 12V DC or AC
RMS within the temperature measuring range, to
avoid damage to the meter.
Method of measuring temperature:
The MS3203 multifunction socket with K-type
temperature probe is required for measuring temperature.
1. Rotate the knob to the TEMP position. The LCD will
display “OL” and temperature unit °C.
2. When inserting the multifunction socket, insert “COM”
and “V” leads of the socket in the comm end and
current MA jacket respectively.
3. Then insert the temperature probe into the side
temperature jacket of the multifunction socket.
Note the polarity of the attachment. The LCD will
display the temperature of the current environment.
4. The other end of the temperature probe
(the temperature sensor) is put into the object to be
tested. The LCD will display the temperature at the
location of the current sensor.
5. Press the “FUNC” key to convert the measured value
to °F, or set the temperature unit to °F first before
measuring.
When the symbol shows on the display during
use of the meter, you must replace the batteries, to
avoid affecting the normal use of the meter.
Method of replacing batteries:
1. Disconnect the test wire. Switch off the power.
2. Open the battery cover on the rear of the case with
the screwdriver, and remove the batteries.
3. Install batteries with same specification,
and secure the cover.
6.2 Fuse Replacement
Steps for replacing fuse:
1. First remove the test wire, and switch off the meter.
2. Open the battery cover on the rear cover with the
screwdriver, and remove the damaged fuse.
3. Install a fuse with same specification, put the battery
cover in place again, and tighten the screws.
6.3 Cleaning
Please wipe the surface of the meter with the soft cloth
and mild detergent, if necessary. Do not use organic
solvents as they will corrosion the meter's case.

HYS006665