Mastech MS8240D User manual

Digital Multi Meter
OPERATING INSTRUCTION
Table of Contents
1．Introduction
2．Safety note
3．Explanation of Controls and Indicators
3-1. Product illustration
3-2. Functional push button
3-3. LCD display
4．Specification
4-1. General Feature
4-2. Electrical Specification
5．Measurement operation
5-1. Push key function
5-2. DC voltage & AC voltage measurement
5-3. Resistance measurement
5-4. Continuity & Diode check
5-5. Capacitance Measurement
5-6. Frequency & Duty Cycle Measurement
5-7. DC/AC uA measurement
5-8. DC/AC mA measurement
5-9. DC/AC 10A measurement
6. Maintenance
6-1. Replacing the battery
6-2. Replacing the fuse
6-3. Cleaning and Decontamination

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7. USB interface for communication to computer.
7-1. Connect the Meter to Personal Computer(PC) with USB
cable
7-2. Installation of application software
1. Introduction
This Meter is a handheld and battery operated Digital Multi Meter(DMM)
with multi function. This Meter is designed to meet IEC1010-1 CAT III 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.
The MS8240D are a high performance, low power consumption and 4 1/2 digits
(22000 counts)
With 46 segments bar graph.
It is have True-RMS function forAC voltage andAC current measurement.
Most alternating voltage and current are expressed in effective value, which are
referred to RMS (Root-Mean-Square) value. The effective value is the square
root of the average of the square of alternating current or voltage value. But
they actually measure the average value of input
Voltage or current, assuming the voltage or current to be a sine wave. Therefore,
the meter with rectifier type circuit are in error if the input voltage or current
has some other shape than a sine wave. This operating instruction covers
information on safety and caution. Please read relevant information carefully
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and observe all the warnings and note strictly.
2. Safety note
Warning
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:
●Do not apply more than the rated voltage, of marked on the meter, between
the input terminal and grounding terminal..
●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 .
●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.
●Disconnect circuit power and discharge all high voltage capacitors before
testing continuity, diode, resistance, capacitance or current.

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Note international Electrical Symbol.
Dangerous Voltage
Ground
AC （Alternating
current）
Warning see
explain in manual
DC (Direct Current)
Double insulation
AC or DC
Fuse
Measurement category(over voltage category):
This instrument is meet the safety condition of CAT III. The
equipment is used
for measurement in building facilities. Examples are measurements on
distribution boards, circuit breaker and industrial equipment located in
fixed facilities, as a fixed
motor.
If the equipment (include probe assembly; type:T
3009, 10A 1KV
CAT III) is used in a manner not specified by
the
manufacturer, the protection provided by the equi
pment/probe
assembly may be impaired. If necessary, the probe assembly
must be replaced with the type specified in this manual.
3. Explanation of controls and indicators
3-1. Meter illustration
①LCD display
②“REL”push button
③“RANGE”push button
④⑽“BKLIT”/ “PC-Link”push button
⑤“MAX/MIN”push button
⑥“HOLD”push button
⑦“FUNC”push button
⑧“VAHz/%”push button

⑨“PEAK”push button
⑾Rotary Switch(Knob)
⑿Input terminal
⒀“COM”terminal
⒁“10A”input jack
⒂“uA/mA”input jack
3-2. Functional push button
Push button
Function
Func
“FUNC”key is the function select key that acts with trigger.
Use the key as switch of DC/AC,
Resistance/Continuity/Diode .
HOLD
Press “HOLD”to enter and exit the hold mode in any mode.
That act with trigger.
MAX/MIN
This key is act with trigger. Press this key once, the maximum
value is holding (Will displays ‘MAX’symbol in the
LCD)and press once again this key, the minimum value on
holding(Will displays ‘MIN’symbol in the LCD).When
“MAX/MIN”key is pressed for third time, the meter
displays max value, and then, “MAX”and “MIN”symbol
is blinking. The meter returns to normal operation if
“MAX/MIN”key is pressed and held for longer than once
second. after pressing the key, A/D will keep working, and the
display value are always up dated and kept the maximum or
minimum value. (The actual gained value is not the peak
value.). Pressing “HOLD”key in the MAX/MIN mode
Makes the meter stop updating the maximum or the minimum
value.
RANGE
It is the auto/manual measurement push key that act with
trigger. The default is auto measurement when power is on.
To press once time, will switch to manual measurement. If
continue to press the key in the top range, the meter will jump
to the lowest range, and recirculate orderly. If press and hold
this key Over 1second, the meter will switch toAuto
Measurement mode.
REL
Press the “REL”key, you can measure the relative value and ‘REL’sign
will appears on the LCD display in the relative mode.
What is meant by relative value? Press the “REL”key, the meter make
the first measured value into a reference value (You must be decide a
reference value as the input signal.) , and the meter store the displayed
reading as a reference value.
The relative measured value that displayed in LCD is achieved by
subtracting a reference value from the present reading value.
Vx - Vref=Vdisplay
Max/Min mode can be nested in REL mode. The meter displays
maximum or minimum value relative to the reference when
“Max/Min”is pressed in REL mode. This time, pressing “HOLD”
key .the meter stop updating the LCD
displayed value.
VAHz/%
When press this key in the voltage or current measurement mode, the
meter
Will switch to frequency measurement mode, you can reading frequency
value of the present measured voltage or current.
This key acts in activation. Press “VAHz/% ”key when frequency mode
is in operation, the meter will switch to duty cycle measurement mode.
Press this key again to switch to frequency measurement mode also.

Duty cycle range is within 5.0% to 94.9%. If the source frequency duty
cycle is smaller than 5.0%, the ‘UL’sign will be shown on the LCD
display, and then if the duty cycle is larger than 94.9%, the ‘OL’sign
will be shown on the LCD display.
PEAK
Entering PEAK mode will automatically execute peak calibration, if
peak calibration was never done before. When press this key, the meter
can measure maximum peak value, and ‘Pmax’sign will be shown on
the LCD display. when press this key again, the meter measure
Minimum peak value and ‘Pmin’sign will be shown on the LCD
display. If press and held this key over 1 second in ‘Pmin’active, the
meter returned normal operating mode..
BL/
PC-Link
This key is used control Backlight. This key is act with trigger. When
press the key, will enable Backlight for 60 sec. Press the key again
within 60 sec, Backlight will disable. When press this key more than
3secs , ‘PC-Link’sign will be shown on the LCD display, this means
serial data output is enabled.
3-3. Display indicators
Number
Indicator
Meaning
1
Auto
The meter is in the auto range mode.
2
DC voltage or current
3
AC voltage or current
4
Diode
5
MAX
Maximum value
6
MIN
Minimum value
7
HOLD
Data hold
8
Pmax, Pnin
Maximum peak value
and Minimum peak value
9
Low battery indicator
10
MKΩ
ΩKΩMΩis unit of resistance
11
℃/℉
The unit of temperature
(℃: Centigrade; ℉: Fahrenheit)
12
umVA
uV mV V is unit of voltage
uA mAA is unit of current
13
－
Indicate negative reading
14
REL
Relative measurement
15
%
Duty cycle
16
numF
Capacitance Units.
17
Auto- power OF


 

Fig. 2 L C D
4. Specification
4-1. General Feature
●Auto ranging DMM , that full scale is 22000 counts
●Display : 4 1/2 digit LCD display with 46 segment bar graph.
●Over load protection: Used the PTC protection circuit for Resistance,
capacitance
And frequency measurement.
●DATA HOLD function
●MAX/MIN value measurement function
●AUTO/MANUAL Mode selection
●Back Light
●Low battery indication
●True- RMS measurement for AC voltage /AC current measurement
●Relative value measurement function
●USB interface for communication to the computer.
●Auto Power- OFF. The meter has a default auto-power function. If the meter
is idle for more than 15minutes, the meter automatically turns the power off.
User to disable Auto-power OFF, may be power on the meter when any of
the push function, except for HOLD is pressed down.
●Operating temperature & Humidity: 0 ~ 40℃(32 ~104 ℉) & < 80% RH
●Storage temperature & Humidity: -10 ~ 50℃(14 ~ 122 ℉) & <70%RH
●Power Supply: 1.5V Battery(AA Type) x 4
●Safety Class: IEC1010-1, CAT III
●Dimension (L x W x H) & Weight: 205 x 102 x 58mm, Approx. 390g.
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●Environmental condition: （1）Indoor use；
（2）Altitude up to 2000meter.
Accessory：
[1] MS3202 Socket for temperature measurement --- 1pc
[2] USB Cable --- 1pc
[3] CD （with USB program）--- 1pc

4-2. Electrical Specification
Function
Range
Best.
Resolution
Accuracy
Over Load
Protection
DC Voltage
2.2/22/220/1000V
0.1mV
±
(0.05%rdg+3dgt）
○
AC Voltage
(40-400Hz)
2.2/22/220/700V
0.1mV
±(0.8%rdg+4dgt)
○
DC mV
220mV
0.01mV
±
(0.05%rdg+3dgt)
○
AC mV
(40-400Hz)
220mV
0.01mV
±(0.8%rdg+4dgt)
○
DC Current
220u/2200u/22m/
220m/10A
0.01u
±(0.8%rdg+4dgt)
○
AC Current
(40-400Hz)
220u/2200u/22m/
220m/10A
0.01u
±(1%rdg+3dgt)
○
±(1.5%rdg+3dgt)
○
Resistance
220/2.2K/22K/220K/
2.2M/22M/220MΩ
0.01Ω
±(0.8%rdg+2dgt)
○
Capacitance
22n/220n/2.2u/22u/220u/
2.2m/220mF
1nF
±(2.5%rdg+3dgt)
○
Frequency
22Hz/220Hz/2.2KHz/
22K/220KHz
0.01Hz
±(0.2%rdg+3dgt)
○
Continuity
Check
Buzzer sounds
at less than
30Ω
Open circuit voltage:
about 2.7V
○
Diode
Check
Testing Current:
About 1.5mA
Open circuit voltage:
about 2.7V
5. Measurement operation
5-1. Push key function
All the enabled push key function will be reset when the measurement mode
is changed by
Function rotary switch . Change measurement mode by “FUNC”key will
reset enabled range,
“HOLD”, “MAX/MIN”, “REL”and “PEAK”function. The following table
lists .The available push key function versus every measurement mode.
KEYS
MODE
RANGE
HOLD
Max/Min
REL
PEAK
VAHz
Voltage
○
○
○
○
○
○
Current 1
○
○
○
○
○
○
Current 2
X
○
○
AC
○
○
Resistance
○
○
○
○
X
X
Capacitance
○
○
○
○
X
X
Frequency
○
○
X
X
X
○
Duty cycle
X
○
X
X
X
X
Continuity
X
○
○
○
X
X
Diode
X
○
○
○
X
X

Note: Current 1 includes Auto uA, Auto mA, 10A mode.
Current 2 includes Manual 2.2A, 10A mode.
5-2. DC & AC voltage measurement
Warning
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 750Vrms although
readings may be obtained.
To measure mV(millivolt) you can set the rotary switch to mV range, this
range is 220.00mV only.
The DC voltage range are 2.2000V 22.000V 220.00V and 1000V; and then.
The AC voltage ranges are 2.2000V 22.000V 220.00V 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. Set the rotary switch to mV or V position.
Default status is DC voltage measurement mode; and thenAC voltage
measurement mode may be select by FUNC push key.
3. Connect the test lead across with the object being measured.
The measured value will be show on the LCD display.
Note:
When DC orAC voltage measurement has been completed,
disconnect the connection
between the testing lead and the circuit under testing.
5-2. Resistance measuremen
The resistance range are: 220.00Ω2.2000KΩ,22.000KΩ, 220.000KΩ,
2.2000MΩ.
22.000MΩand 220.0MΩ( Note: it is not 220.00MΩto prevent the
least digit from jumping).
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 Ωposition. At the start, the meter is
resistance mode.
In this range, you can switch to continuity and diode check mode by the
“FUNC”key. Its sequence as follows:
Ω→→→Ω
3. Connect the test lead across with the object being measured.
The measured value will be show on the LCD display.
Note:
The test lead can add 0.1Ωto 0.2Ωof error to resistance
measurement. To obtain precision reading in low-resistance
measurement, that is the range of 220.00Ω, 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

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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.
5-3. Diode/Continuity check
①insert the red test lead into the “VΩ”terminal and the black test lead
into the COM terminal.
②Set the rotary switch to Ωposition. To select the
continuity mode, press one time the “FUNC”push button.
③The buzzer sound if the resistance of a circuit under test is less than 30
Ω.
④Select the diode check mode by the “FUNC”key.
⑤Use the diode test mode to check diodes, transistors and other
semiconductor device. In the diode test mode sends a current through
the semiconductor junction, and the measure the voltage drop across
the junction.A good silicon junction drop between 0.5V and 0.8V.
⑥For 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
display.
⑦Reverse the test lead and measure the voltage across the diode again.
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If diode is good, the display shows “OL”.
If diode is shorted, the display shows 0 (zero) in both direction.
If display shows “OL”in both direction, the diode is open.
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5-4. Capacitance measurement
Warning:
To avoid damage to the Meter or to the equipment under test,
disconnect power and
discharge all high-voltage capacitors before measuring
capacitance.
You can use the DC voltage function to confirm that the capacitor
is discharged.
Capacitance ranges are 22.00nF, 220.0nF, 2.200uF, 22.00uF, 220.0uF,
2.200mF and 220.0uF.
To measure capacitance, connect the Meter as follows:
1. Set the rotary switch to“”position.
2. For the convenience of user, provided the MS3202 Multi
Function Socket as accessory. First time, insert the Socket to
the “VΩ”input terminal and “COM”terminal, and then
insert the capacitor to the two holes on the Socket. The pin
marked “Cx/Lx/Temp”is pointed to
the “VΩ”input terminal, and the pin marked “COM”is
pointed “COM”input terminal respectively.
The measured value will be displayed on the LCD display.

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NOTE:
[1] You can used the MS3202 Socket according to the capacitor pin size.
. The pin( marked ”Cx/Lx/Temp”) of MS3202 Socket must be pointed
to the “VΩ”input terminal.
If the capacitor pin is thick ( i.e, Diameter of pin >1 mm),
the insert to the MS3202 socket is disabled. In this case ,
directly insert the capacitor under test to the “COM”and
“VΩ”terminals, or using the leads(probe) to measuring
capacitance of capacitor.
[2] To increase the accuracy of capacitance measurement when measuring
under 5nF capacitance, you can connecting 0.15uF Capacitor in parallel
with the capacitor being
measured , or use relative measurement mode to automatically subtract the
capacitance build-in equalized capacitance and residual capacitance of
PCB lead wire from the result. .
5-5. Frequency & Duty cycle measurement
The normal measurement ranges are 22.00Hz, 220.0Hz, 22.000KHz,
220.00KHz,
2.2000MHz., 22.000MHz and 220.00MHz.
1. Set the rotary switch to ‘Hz/%’position，and the‘Hz’sign shown
on the LCD display.
2. Insert the red test lead into the “ VΩ”input terminal and the black
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3. test lead into the “COM”terminal.
4. Connect the test leads across with the circuit under testing. The
measured value shown.
on the LCD display.
5. To switch to the duty cycle mode , press “VAHz/%”. Push key.
The duty cycle mode range is within 5.0% to 94.9%. The minimum
resolution is 0.1%.
If the sorce frequency duty cycle is smaller than 5.0%, the “UL”sign
will be shown on
The LCD display, and then, if the duty cycle is larger than 94.9%, the
“OL”sign will be shown on the LCD display.
NOTE: Input signal level must be higher than 0.7V (it is sensitivity).
5-6. DC uA/AC uA measurement
1. Set the rotary switch to the uA position.
2. Select the DC uA or AC uAwith “FUNC”push button. The meter
default to DC current measurement mode.
3. Turn off power to the circuit. Break the circuit point to be measured.
4. Connect the two test lead to complete the broken circuit.
5. If the measured current is too high, the display will indicate “OL”. In
this care, the higher current range (mA orA) should be selected.
5-7. DC/AC mA measurement
1. Turn off power to the circuit. Set the rotary switch to the mA position.
2. The meter default to DC current measurement mode. SelectAC mA
measurement mode by “FUNC”push button.
3. Break the current path to be tested. Connect the red test lead to the

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4. more positive side of the break and the black test lead to the more
negative side of the break.
5. Turn on power to the circuit. The measured value show on the display.
5-8. DC/AC 10A measurement
1. Turn off power to the circuit. Set the rotary switch to theA position.
Default mode is
DC A measurement mode and selectAC A measurement mode by the
FUNC key.
2. Insert the red test lead into the input terminal marked as “10A”.
3. The measuring procedure is same as that of mA or uA.
Note:
For safety sake, the measuring time for high current should be ≤
10 second for each measurement and the interval time between
two measurement should be greater than 5 minutes.
When current measurement has been completed, disconnect the
connection between the testing lead and the circuit under test.
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6. Maintenance
6-1. Replacing the battery
When meter display the battery must be replace to maintain
normal operation.
①Disconnect and remove all test probes from any live
source and meter.
②Open the battery cover on the bottom case by
screwdriver.
③Remove old battery and snap new one into battery
holder
6-2. Fuse replacement
Replacing the defective fuse should the done according to the following
procedure.
①To avoid electrical shock, remove the test lead and any
input signal before opening the bottom case.
②Remove the battery cover and remove the three screws from
the bottom case.
③Lift the button case until it gently unsnaps from the top case.
④Remove the defective fuse and insert a new fuse of the same
size and rating.
⑤Replace the bottom case and reinstall all the screw.

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6-3.Cleaning and Decontamination
The meter can be cleaned with soft clean cloth to remove any oil, grease or
grim.
Do not use liquid solvent or detergent.
7. USB Interface with a Personal Computer (PC)
7-1. Connect the Meter to PC with USB cable
In this meter used special USB cable with A type USB
connector and
mini-USB connector.
7-2. Installation of application software:
First you must be install the <USB –RS232 Driver> & < MS8240D USB
Program>.
The install process is automotive.
First, insert the CD to the CD driver of PC.
1. Double click G：\\MS8240D USB PROGRAM\driver-232\steup.exe
2. The dialog window will be displayed in the screen of PC as following, and
then click the <INSTALL> Soft key on the screen.
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3：Click the <FINISH>soft key after the setup is completed.
4：Double click G:\\MS8240D USB PROGRAM\MS8240D USB PROGRAM
\steup.exe
5：Connecting the USB Cable between the DMM and PC。

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6：First, execute the file: \\PCLink for
multimeter\multimeter.exe , so that wll display
Following dialog window.
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7：Select the communication port from the <ComSelect> menu. You are
must be Select the COM4.
8：Power on the DMM and then push the “PC-Link”button more than 3secs
to inert to the
Communication mode. The ‘PC-Link’symbol will be displayed on the
LCD.

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9: Click the <Connect> key on the screen . The measured data will be
displayed on the screen of PC as following screen.
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*** Note：
If communication is failed，should be adjusting the interval
betwee the two infrared light emitting diode and
phototransistor on the SUB PCB.
First, open the back case and applied ±3V power supply to
the spring terminal on the SUB PCB. You can lightly stir the
two device and observe the screen as the same time.
In common case, the light emitting diode and
phototransistor is not easy fail. However, the interval
between the two device is affect to the
data (ASCII code) transfer.
—
END —.