Mastech MS8239A User manual

MS8239A
User's Manual
Digital Multimeter
HOLD
10A
COM
MAX
10A/ 500V
MAX
200mA/250V
600V MAX
600V CAT III
IEC61010-1
BATT.
A
V
V
200
600
20m
200m 10A
200
2k
20k
200k
2M
2
20
200
600
200m
9V
1.5V
12V
MS8239A
Auto Power Off
DIGITAL MULTIMETER

CONTENTS
Safety Indicators..............................1
CONTENTS
Meter Appearance..............................5
Safe Working Habits..........................2
Overview..........................................1
Electric Symbols...............................4
Meter Instructions.............................5
Display..............................................5
Measuring Operation.........................7
Data Hold
DC/AC Voltage Measurement.............7
..........................................7
DC Current Measurement
Resistance Measurement
...................8
...................9
Continuity Measurement...................10
Diode Test........................................10
Battery Test......................................11
General Specifications.......................11
Accuracy Indicators...........................12
DC Voltage..........................................13
AC Voltage..........................................13
Resistance Measurement.....................14
Diode..................................................14
Continuity Measurement.......................14
DC Current..........................................15
Battery Test.........................................15
Maintenance.....................................15
General Maintenance...........................16
Replace Battery...................................16
Replace Fuse.......................................17

01
02
Overview Safe Working Habits
To avoid electric shock or personal injury, please
read “safety information” and “warning and
related notes” carefully before using the meter.
The MS8239A is a small hand-held, safe and reliable
3.5” digital multimeter with stable performance and
novel structure. It can be used to measure DC
voltage, DC current, resistance, diode forward
voltage drop, circuit continuity and to test batteries.
It is an ideal maintenance tool easily carried by a
large number of users.
Warning To avoid possible electric shock or personal injury as
well as damage to the meter or measured objects,
please use the meter according to the following
procedures:
Safety Instructions
The MS8239A digital multimeter has been designed
according to International Electro Safety Standard
IEC-1010 (61010-1@IEC: 2001) concerning safety
requirements for electronic measuring instruments
and hand-held digital multimeters. It meets the
requirements for CAT.III 600V of IEC1010 and grade
2 for pollution.
• Users should use the meter strictly according to
the provisions of this manual. Otherwise, the
warranty for the meter may become invalid.
• The warnings in the user manual are used to remind
users of possible dangers or dangerous actions.
• The notes in the user manual are to remind users
of conditions or actions that may cause damage
to the measured object.
• Check the case before using the meter. Don't use the
meter with damaged case. Check to see if the case is
cracked or lacks plastic parts. Please pay special
attention to the joint insulating layer.
• Check to see if the test wire has insulation damage or
bare metal. Check test wire continuity. If the wire is
damaged, please replace it with a new one before
using the meter.
• Measure known voltage with the meter to verify that
the meter is working properly. If the meter is working
abnormally, stop using it immediately. A protective
device may be damaged. If there is any doubt, please
have the meter inspected by a qualified technician.
• Do not test voltage exceeding rated voltage marked
on the meter.
• When testing voltage exceeding 30v AC voltage RMS,
42v AC peak or 60v DC, be particularly careful to
avoid electric shock.
• When measuring, use correct jack, and select the
proper function and measuring range.
• Do not use the meter in explosive gas, vapor or dusty
environments.
• When using the probe, fingers should be behind the
probe protection device.

03
04
• When connecting circuits, connect the common test
line first, then connect the charged test line. When
disconnecting circuits, disconnect the charged test
line first, then disconnect the common test line.
Before measuring resistance, continuity, and diodes,
first turn off power and discharge all high voltage
capacitors.
• If the meter is not used in accordance with the
instructions, the meter's safety protective function
may become invalid.
• For all DC measurements, to avoid the risk of
electric shock, please use AC function to verify the
existence of any AC voltage. Then, select DC
voltage measuring range equal to or greater than
the AC measuring range.
• Before measuring current, please check the meter
fuse, shut off power to the circuit to be tested, then
connect the meter and energize the circuit.
• When opening the case (or part of the case), turn
the meter off.
• When the battery low voltage indicator “ ”
becomes lit, replace the battery at once. A low
battery will cause meter reading errors and may
result in electric shock or personal injury.
• Before opening the case or the battery cover,
remove the test wire from the meter.
When maintaining the meter, use replacement parts
specified by the factory.
Electric Symbols
Important safety information
AC (Alternating Current)
DC (Direct Current)
AC or DC
Ground wire
Fuse
Accord with the related EU laws and regulations

05
06
(1) LCD display
(2) Data hold key
(3) Function selection rotary switch
(4) Positive input jack of 10A (connected with the
red test probe).
(5) All the common input jacks for measuring
(connected with the black test probe).
(6) Positive input jack of voltage, resistance, mA
current, diode, continuity and battery test
(connected with the red test probe).
Meter Instructions
Meter Appearance
Display
(1) Battery low voltage indicator
(2) Data hold indicator
(3) Numerical value display
(4) Numerical value polarity indicator (negative sign)
HOLD
10A
COM
MAX
10A/ 500V
MAX
200mA/250V
600V MAX
600V CAT III
IEC61010-1
BATT.
A
V
V
200
600
20m
200m 10A
200
2k
20k
200k
2M
2
20
200
600
200m
9V
1.5V
12V
MS8239A
Auto Power Off
DIGITAL MULTIMETER
1
2
3
4
5
6

07
08
Measuring Operation DC Current Measurement:
Data Hold
The data hold function can keep the current readings
on the display. To enter and exit reading maintenance
mode:
Press the “HOLD” key, the reading will be stored
and “H” symbol will display on the LCD display.
Press the “HOLD” key again to return the meter
to the normal measurement state.
1
2
AC/DC Voltage Measurement:
Rotate the function selection switch to appropriate
AC or DC voltage measurement position.
Connect the black and red test probes to the COM
input jack and VΩmA input jack, respectively..
Measure the voltage of circuit to be tested with
other ends of test probes (connected with the
circuit to be tested in parallel).
Read the measured value from the LCD display.
When measuring the DC voltage, the display will
simultaneously show the voltage polarity which is
connected with the red test probe.
1
2
3
4
Don't measure any RMS voltage higher than 600V
DC or AC, to prevent injury or damage to meter
and equipment.
Warning
Turn off the power to the circuit to be tested.
Discharge all the high voltage capacitors on the
circuit to be tested.
Rotate the function selection switch to the
appropriate DC current position.
Depending on the size of the current to be
measured, connect the red test probe to 10A or mA
input jack; connect the black test probe to COM
input jack.
Turn off the circuit to be tested. Connect the black
test probe to one end of the disconnected circuit
(low voltage relatively), and the red test probe is
connected to the other end of disconnected circuit
(high voltage relatively). (Reversing test probes
would make reading become negative, but the
meter won't be damaged.)
Connect the power supply to the circuit, then read
the display reading. If the display shows only “1”,
the input is out of the selected input range. In this
case, rotate the switch to a higher measuring range.
1
2
3
4
5
To prevent injury or damage to meter and
equipment, do not make current measurements
if voltage exceeds 250V.
Warning

09
10
Before measuring current, first check the meter's
fuse. When measuring, use correct input end and
function. When the test probe is inserted to the
current input end, don't connect the other end of
the test probe with any circuit in parallel.
Note
Resistance Measurement:
Rotate the function selection switch to an
appropriate resistance position, and turn off the
power to the circuit to be tested
Connect the black and red test probe to COM
input jack and VΩmA input jack, respectively.
Measure the resistance of the circuit with other
ends of test probes.
Read the resistance value from the LCD display.
1
2
3
4
Here are some tips for measuring resistance:
• The resistance measured on a circuit is usually
different from the rated value of resistance. This is
because the test current of the meter will flow
through all the possible channels between the
test probes.
• When measuring low resistance, to ensure the
accuracy of the measurement, make a short circuit
between the test probes and read the resistance
value of the short circuit. This resistance value
should be subtracted after measuring the
resistance to be tested.
• When there is no input (for example, open circuit),
the display will show “1”, which means that the
measured value is out of range.
When measuring resistance or circuit continuity,
to avoid injury or meter damage, turn off the power
to the circuit and discharge all capacitors.
Warning
Continuity Measurement:
1
2
3
4
Rotate the function selection switch to continuity
measurement position, and turn off the power to
the circuit to be tested
Connect the black and red test probe to COM input
jack and VΩmA input jack, respectively.
Measure the circuit to be tested with other two ends
of the test probes.
If the measured circuit resistance is less than
about 50Ω, the buzzer will sound continuously.
When measuring resistance or circuit continuity,
to avoid injury or meter damage, turn off the power
to the circuit and discharge all capacitors
Diode Test:
Warning
Rotate the function selection switch to diode
position, and turn off the power to the circuit to
be tested
Connect the black and red test probe to COM input
jack and VΩmA input jack, respectively.
1
2

11
12
Connect the black and red test probe to cathode
and anode of the diode to be tested, respectively.
The meter will display the diode's forward bias
voltage value. If the test probe polarity is reversed,
the meter will display “1”, which distinguishes the
diode's cathode and anode.
3
When measuring diodes, to avoid injury or meter
damage, turn off the power to the circuit and
discharge all capacitors.
Warning
Battery test
Place the function measuring range switch to the
battery testing position.
Insert the red probe to VΩmA input jack. Insert the
black probe to COM input jack.
Connect free end of the red probe to positive and
the free end of the black probe to negative end of
the battery to be tested.
Read the result from the LCD display.
Don't input voltage higher than 60V DC or 30V AC,
to prevent electric shock or meter damage.
General specifications
Warning
• Operating environment and condition: 600V
CAT. III, pollution grade: II.
Elevation < 2000 m
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2
3
4
• Environmental temperature and humidity: 0~40°C,
<80% RH (do not use meter when temperature <10°C).
• Storage temperature and humidity: -10~60°C and
<70% RH (remove the battery).
• Temperature coefficient: 0.1 Accuracy /°C(<18°C
or >28°C).
• The maximum allowable voltage between
measurement end and ground: 600V DC or 600V
AC RMS.
• Fuse protection: grade mA: fuse F200mA/500V
grade 10A: fuse F10A/500V
• Sampling rate: about 3 times/s.
• Display: 3.5” digital LCD display.
• Over-range indication: LCD will show “1”.
• Low battery indication: When the battery voltage is
lower than the normal operating voltage, “ ”will
display on the LCD display.
• Input polarity indication: automatically display “-”.
• Power supply: AAA 1.5V batteries.
Accuracy Indicators
Accuracy: ±(% of reading + digits) with one year of
warranty. Reference conditions: environmental
temperature is from 18°C~28°C, relative humidity is
not more than 80%.

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14
Resolution Accuracy
200mV
2V
0.1V
0.001V
0.1mV
0.01V
1V
DC Voltage
20V
200V
600V ±(0.8% of reading +3 digits)
Input impedance: 1MΩ
Maximum input voltage: 600V DC or AC RMS, 250V DC
or AC RMS with the measuring range of 200mV.
Resistance
Measuring range
±(0.5% of reading +3 digits)
Resolution Accuracy
200V
600V 1V
0.1V
AC Voltage
Input impedance: 1MΩ
Maximum input voltage: 600V DC or AC RMS, 250V DC
or AC RMS with the measuring range of 200mV.
Frequency response: 40Hz~400Hz, sine wave RMS
(average response)
Measuring range
±(1.2% of reading +10 digits)
Resolution Accuracy
200Ω
2kΩ
0.1kΩ
0.001kΩ
0.1Ω
0.01kΩ
0.001MΩ
20kΩ
200kΩ
2MΩ
Measuring range
±(0.8% of reading +5 digits)
Overload protection: 250V DC or AC (RMS)
2V
Forward DC current:
about 1mA; Reverse
DC voltage: about
2.5V. Display
approximation of
diode forward
voltage drop.
Diode
Measuring
range
Function Test EnvironmentResolution
0.001V
Diode Test
Overload protection: 250V DC or AC (RMS)
When built-in buzzer
sounds, the resistance
to be tested is less than
about 60Ω.
Continuity Measurement
Function Test Environment
Description
Open circuit voltage:
about 2.5V
Overload protection: 250V DC or AC (RMS)

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16
Direct Current
Resolution Accuracy
20mA
200mA 0.1mA
0.01mA
10mA10A
Measuring range
±(1.0% of reading +5 digits)
Overload protection: grade mA: Fuse (F200mA/600V)
protection; grade 10A: Fuse (F10A/500V) protection.
Maximum input current: grade mA: 200mA DC or AC
RMS; grade 10A: 10A DC or AC RMS
When measured current is greater than 2A, the
continuous measurement time cannot be not more
than 2 minutes. Disconnect the current and wait 10
minutes before making another measurement.
±(2.0% of reading +10digits)
Battery Test
Resolution Built-in load resistance
12V
9V 0.01V
0.01V
0.001V1.5V
Measuring range
300Ω
1.8kΩ
36Ω
Overload protection: Fuse (F200mA/500V) protection;
Maintenance
This section provides basic maintenance information,
including instructions for the replacement of fuse and
battery. Do not try to repair the meter unless you are
an experienced maintenance person with the relevant
calibration, performance testing and maintenance data.
To avoid injury or damage to the meter, don't wet
the inner parts of the meter. Before opening the
case or battery cover, remove the connecting
cable between the test probe and the input signal.
Warning
General Maintenance
Regularly clean the meter case with damp cloth and
a small amount of detergent. Do not use abrasives or
chemical solvents. If the input jack becomes dirty or
wet, it may affect the measurement readings.
To clean input socket:
Turn off the meter and pull out all the test probes
from the input jack.
Remove all dirt from the jacks.
Apply detergent or lubricant to a new cotton ball
(such as WD-40).
Clean each jack with a cotton ball and lubricant to
prevent contamination by moisture in the socket.
1
2
3
4
Replace Battery
To avoid incorrect readings and possible electric
shock or personal injury, when “ ” appears on
the meter display, replace the battery immediately.
To avoid electric shock or personal injury, before
opening the battery cover to replace battery, turn
off the meter and make sure that the test probe is
disconnected from the measurement circuit.
Warning

17
Replace Fuse
Please follow these steps to replace battery:
Turn off the power to the meter.
Remove all test probes from the input jacks.
Loosen screws on the battery cover with
screwdriver.
Remove the battery cover.
Remove old batteries.
Replace with two new AAA batteries, placing
the positive and negative ends in their correct
positions.
Replace the battery cover and tighten the screws.
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2
3
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7
To avoid electric shock or personal injury, before
opening back cover to replace fuse, turn off the
meter and disconnect the test probe from the
measurement circuit.
Warning
To replace fuse:
Turn off the power to the meter.
Remove all test probes from the input jacks.
Loosen screws on the back cover with screwdriver.
Remove the back cover.
Remove the blown fuse.
Replace with new fuse with the same type.
Put the back cover and tighten the screws.
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HYS007065