Mastech MS8250A User manual

MS8250A/B
Digital Multimeter
Operation Manual
MS8250A/B Digital Multimeter
Safety information
1. Safety information
Warning
Please particularly note that inappropriate use may cause shock or
damage to the meter. When using, comply with common safety
procedures and completely follow the safety measures stated in the
operation manual.
In order to make full use of the meter’s functions and ensure safety
operation, please carefully read and follow the use methods in the
operation manual.
The meter meets GB/T 13978-92 digital multimeter general technology
conditions, GB4793.1-1995 (IEC 61010-1, IEC 61010-2-032) electronic
measurement instrument safety requirements with secondary pollution and
over-voltage standard of CAT Ⅳ600V.
Please follow the safety operation guidelines to ensure the safe use of meter.
The meter will provide satisfactory service to you if you use and protect it
appropriately.
1.1 Preparation
1.1.1 When using the meter, the user should comply with standard safety
rules:
- General shock protection
- Prevent misusing the meter
1.1.2 Please check for damage that may have occurred during transportation
after receiving the meter.
1.1.3 If it should be stored and shipped under hard conditions, please confirm
if the meter is damaged.
1.1.4 Probe should be in good condition. Before use, please check whether the
probe insulation is damaged and whether metal wire is bare (not
properly insulated).
1.1.5 Use the probe table provided with the meter to ensure safety. If
necessary, it should be replaced with another identical probe or one with
the same capacity.- 1 -

MS8250A/B Digital Multimeter
Safety information
1.2 Usage
1.2.1 When using, select the correct function and measuring range.
1.2.2 Don't exceed the indicated maximum of each measuring range.
1.2.3 When measuring circuits with the meter connected, do not touch the
probe tip (metal part).
1.2.4 When measuring, if the voltage to be measured is more than 60 V DC or
30 V AC (RMS), always keep your fingers always behind finger
protection device.
1.2.5 Don’t measure voltage greater then 600 V.
1.2.6 For manual measuring range, when the value to be measured is
unknown, select, the highest measuring range.
1.2.7 Before rotating conversion switch to change measuring function,
remove probe from the circuit to be measured.
1.2.8 Don't measure resistors, capacitors, diodes and circuit connections with
power.
1.2.9 During tests of current, resistors, capacitors, diodes and circuit
connections, avoid connecting the meter with voltage sources.
1.2.10 Do not measure capacitance before capacitor is discharged completely.
1.2.11 Do not use the meter in explosive gas, vapor or dusty environments.
1.2.12 If you find any abnormal phenomena or failure on the meter, stop using
it immediately.
1.2.13 Do not use the meter unless the bottom case and the battery cover are
completely fastened in their original places.
1.2.14 Don't store or use the meter in direct sunlight or high temperature and
high humidity conditions.
1.3 Mark
Note (Important safety information. Refer to the operation manual)
Can be used for dangerous electric conductor.
Double insulation protection (class II)
CAT ⅣAccording to pulse voltage tolerance protection level provided by
IEC 61010-1 standard overvoltage (installation) level III and
pollution degree 2.
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MS8250A/B Digital Multimeter
Safety information
The meter complies with EU standard
Grounding
1.4 Maintenance
1.4.1 Don't try to open the meter bottom case to adjust or repair. Such
operations only can be operated by technicians who fully understand the
meter and electrical shock hazard.
1.4.2 Before opening the meter bottom case or battery cover, it should remove
probe from the circuit to be measured.
1.4.3 To avoid incorrect readings and possibly causing electric shock, when
" " appears on the meter display, replace the battery immediately.
1.4.4 Clean the meter with damp cloth and mild detergent. Do not use
abrasives or solvents.
1.4.5 When the meter is not used, switch the measuring range to OFF
position.
1.4.6 If the meter is not used for long time, remove the battery to prevent
damage to the meter.
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MS8250A/B Digital Multimeter
Description
2. Description
- The meter is a portable, professional measuring instrument with LCD
display and back light for easy reading by users. Measuring range switch
is operated by one hand for ease of operation. The meter has overload
protection and low battery indicator. It is an ideal multifunction meter no
matter for professionals, factories, schools, fans or family use.
- The meter is used to measure AC current, DC current, voltage, DC voltage,
frequency, duty ratio, resistance, capacitance measurement and circuit
connection, diode test.
- The meter has automatic measuring range and manual measuring range.
- The meter'sAC current and AC voltage are measured with True RMS.
The meter has:
- reading hold function.
- relative measuring function.
- max. measuring function.
- min. measuring function.
- auto power off function.
- When measuring AC voltage and AC current, the meter can measure
frequency of AC voltage and AC current synchronously.
2.1 Part name
⑵Non-contact voltage detection indicator
⑶LCD display
⑷Key
⑸Functional rotary switch
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MS8250A/B Digital Multimeter
Description
- 5 -

MS8250A/B Digital Multimeter
Description
⑹Input socket
⑺Non-contact voltage induction area
2.2 Switch, button and input jack description
HOLD key: used for reading hold.
FUNC key: used for measuring function switch.
RANGE key: used for switching automatic measuring range or manual
measuring range.
REL key: used for switching relative to measuring function.
Hz% key: used for duty ratio and frequency measurement function switch.
Backlight key: turn on backlight
OFF position: used for shutting off the power.
Jack: voltage, resistance, frequency, duty ratio, capacitance,
diode, circuit connection input wire connecting terminal.
Jack: common wire connecting terminal
Jack: μA and mA current input terminal.
Jack: 20Acurrent input terminal.
2.3 LCD display
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MS8250A/B Digital Multimeter
Description
AC
DC
Diode
Audible continuity
AUTO
Automatic measuring range mode
MAX
Maximum measurement state
MIN
Minimum measurement state
Low battery
%
Percentage (duty ratio)
Hz, kHz
Hertz, Kilohertz (frequency)
mV, V
Millivolt, Volt (voltage)
μA, mA, A
Ampere (current)
nF, μF, mF
Microfarad, Millifarad (capacitance)
Ω, kΩ, MΩ
Ohm, Kilohm, Megohm (resistance)
REL
Relative measurement mode
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MS8250A/B Digital Multimeter
Description
3. Specifications
The meter should be recalibrated annually. When calibrating,
temperature should be 18°C～28°C, and relative humidity should be less than
75%.
3.1 General
3.1.1 Automatic measuring range and manual measuring range
3.1.2 Full measuring range overload protection
3.1.3 The maximum allowable voltage between measurement end and ground:
600V DC or AC (RMS)
3.1.4 Operational height: maximum 2000 m
3.1.5 Display: LCD
3.1.6 Displayed maximum value: digit 3999
3.1.7 Polarity indication: automatical indication, ‘-’ means negative polarity.
3.1.8 Exceeding measuring range display: ‘0L’ or ‘-0L’
3.1.9 Sampling time: digital display is about 0.4 sec/time, analog display 0.04
sec/time (except current measurement). When measuring current, digital
display is about 1 sec/cycle, analog display 0.1 sec/cycle.
3.1.10 Unit display: has function and power unit display.
3.1.11 Auto off time: 30 sec
3.1.12 Operating power supply: 9V, 6F22 battery.
3.1.13 Battery low voltage indication: LCD displays symbol.
3.1.14 Temperature coefficient: less than 0.1×accuracy/°C
3.1.15 Operating temperature: 0°C ～40°C
3.1.16 Storage temperature: -10°C ～50°C
3.1.17 Dimension: 180×86×52mm
3.1.18 Weight: about 250 g (not including battery)
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MS8250A/B Digital Multimeter
Description
3.2 Technical indicators
Environment temperature: 235°C, relative humidity (RH): <75%
3.2.1 DC voltage
Measuring
range
Resolution
Accuracy
400mV
0.1mV
(0.8% reading + 3 digits)
4.0V
0.001V
(0.5% reading + 5 digits)
40V
0.01V
400V
0.1V
600V
1V
- Input impedance: 10M 
- Overload protection: 400mV measuring range: 250V DC or AC (RMS),
4.0V-600V measuring range:
600V DC or 600VAC (RMS)
- Maximum input voltage: 600V DC
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MS8250A/B Digital Multimeter
Specification
3.2.3 AC voltage
Measuring
range
Resolution
Accuracy
400mV
0.1mV
(1% reading + 5 digits)
4V
0.001V
(0.8% reading + 5 digits)
40V
0.01V
400V
0.1V
600V
1V
±(1.2% reading +3 digits)
- Input impedance: 10M 
- Maximum input voltage: 600V AC (RMS)
- Frequency range: 50 ~ 60Hz
- Response: true RMS
3.2.4 Resistance
Measuring
range
Resolution
Accuracy
400
0.1
(1% reading + 5 digits)
4k
0.001k
40k
0.01k
400k
0.1k
4M
0.001Mk
10M
0.1M
(1.2% reading + 15 digits)
- Open circuit voltage: about 0.4V
- Overload protection: 250V DC orAC (RMS)
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MS8250A/B Digital Multimeter
Specification
3.2.5 Capacitance
Measuring
range
Resolution
Accuracy
40nF
0.01nF
(3.0% reading + 5 digits)
400nF
0.1nF
4F
0.01F
40F
0.01F
100F
0.1F
- Overload protection: 250V DC orAC (RMS)
3.2.6 Diode test
Measuring
range
Resolution
Function
0.001V
Display approximate diode forward
voltage value
- Forward DC current is about 1mA
- Backward DC voltage is about 3.3V
- Overload protection: 250V DC orAC (RMS)
3.2.7 Circuit continuity test
Measuring
range
Resolution
Function
0. 1
If the resistance of circuit to be measured
is less than 50, the meter's built-in
buzzer will sound.
- Open circuit voltage is about 1.2V
- Overload protection: 250V DC orAC (RMS)
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MS8250A/B Digital Multimeter
Specification
3.2.8 Frequency
3.2.8.2 Pass Hz grade:
Measuring
range
Resolution
Accuracy
5Hz
0.01Hz
(0.5% reading + 2 digits)
50Hz
0.1Hz
500Hz
0.001kHz
5kHz
0.01kHz
50kHz
0.1kHz
500kHz
1kHz
5MHz
10kHz
Overload protection: 250V DC or AC (RMS) - measurement signal: Vpp3V
AC signal
3.2.8.3 Duty ratio
Measuring range
Resolution
Accuracy
10 - 95%
0.1%
2.0%
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MS8250A/B Digital Multimeter
Specification
3.2.9 DC current
Measuring range
Resolution
Accuracy
400A
0.1A
(0.8% reading + 2 digits)
4000A
1A
40mA
10A
400mA
100A
20A
10mA
(1.2% reading + 2 digits)
Overload protection:
A and mA grade: Fuse F400mA/250V, A grade: Fuse F20A/250V.
When measuring current is greater than 5A, the continuous measurement time
should not be more than 10 seconds. After measuring, disconnect the current.
3.2.10 AC current
Measuring range
Resolution
Accuracy
400A
0.1A
(1.5% reading + 2 digits)
4000A
1A
40mA
10A
400mA
100A
20A
10mA
(3.0% reading + 5 digits)
Overload protection:
A and mA grade: Fuse F600mA/250V, A grade: Fuse F20A/250V.
- Frequency range: 50 ~ 60Hz
- Response: true RMS
When measuring current is greater than 5A, the continuous
measurement time should not be more than 10 seconds. After
measuring, disconnect the current.
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MS8250A/B Digital Multimeter
Specification
4. Operating guidance
4.1 Reading hold
4.1.1 In the process of measurement, if reading hold is required, press
“HOLD” key, the value on the display will be locked.
4.1.2 Press “HOLD” key again to cancel reading hold.
4.2 Measuring range switch
4.2.1 When turning the conversion switch to current, voltage, resistance,
capacitance, frequency grade, the meter is in automatic measuring range
mode.
4.2.2 Press “RANGE” key, the meter will enter the manual range mode.
Ppress once, the measuring range will go up with one grade. If it is
pressed at the highest measuring range, it will go to the minimum
measuring range.
4.2.3 If the user presses “RANGE” key more than 1 sec, the meter will
restore automatic measuring range.
Note:
Frequency and capacitance measurement can't be set to manual
measuring range mode.
4.3 Relative measurement mode switch
4.3.1 Press “REL” key to enter the relative measurement mode. When
making relative measurement, the measurement value at the moment of
pressing REL key in the internal memory of the meter is called initial value.
The display value after that is the current measurement value - initial value.
4.4 Duty ratio and frequency measurement choice
4.4.1 Press “Hz%” key at Hz grade. The meter will enter the duty ratio
measurement state. Press “Hz%” key again. The meter will enter
frequency measurement state.
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MS8250A/B Digital Multimeter
Operating guidance
4.5 Function switch
4.5.1 When measuring voltage and current, press “FUNC” key to switch AC
voltage and AC current.
4.5.2. When measuring voltage and current, press “FUNC” to switch different
measuring signals.
4.6 Backlight
4.6.1 Press “ ” key to open the backlight, the backlight will
automatically trun off after 20 seconds.
4.7 Automatic 9ower-off
4.7.1 If there is no operation for 30 minutes after turning the machine on, the
meter will automatically power off to save the battrery.
4.7.2 After automatic power-off, press any key to turn the meter on again.
4.7.3 Holding the “FUNC” key when powering on will cancel automatic
power-off function.
4.9 NCV (non-contact voltage detection)
4.9.1 Turn the meter to NCV grade
4.9.2 Place the meter top close to the conductor. When test voltage is
greater than 110 Vac (RMS), the meter induction voltage indicator will turn
on and buzzer will give dripping alarm sound.
Note: 1: Even there is no indication, voltage may still exist. Don't use
non-contact voltage detector to judge whether there is voltage in the wire.
Detection operation could be affected by socket design, insulation thickness,
type and other factors.
2: When inputting voltage on the meter input terminal, due to the existence of
the induced voltage, voltage induction indicator also may light.
3: Interference sources in the external environment (such as flashlight, motor,
etc.) may trigger erroneous non-contact voltage detection.
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MS8250A/B Digital Multimeter
Operating guidance
4.10 AC voltage/DC voltage measurement
Voltage is the potential difference between two points. AC voltage polarity
changes over time, while DC voltage polarity does not change over time.
DC voltage measuring range of this meter: 400.0mV, 4.000V, 40.00V,
400.0V, 600V; AC voltage measuring range of this meter: 400.0mV, 4.000V,
40.00V, 400.0V, 600V. The 400mV measuring range can be entered only in
the manual measuring range mode.
To measure AC and DC voltage:
4.10.1 Rotate switch to voltage position.
4.10.2 Respectively connect black and red test probes to COM input socket
and V input socket.
4.10.3 Measure the voltage of circuit to be tested with other two ends of test
probes. (Connected with the circuit to be tested in parallel)
4.10.4 Read the measuring voltage value from LCD display. When
measuring DC voltage, the display will simultaneously show the voltage
polarity which is connected with red test probe.
4.10.5 Press FUNC key to switch AC voltage, DC voltage measurement.
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MS8250A/B Digital Multimeter
Operating guidance
4.11 Measurement
Resistance range of this meter: 400.0, 4.000k, 40.00k, 400k, 4.000M,
10.00M.
To measure resistance:
4.11.1 Rotate rotary switch to position.
4.11.2 Respectively connect black and red test probes to COM input socket
and V input socket.
4.11.3 Measure the resistance value of circuit to be tested with other two ends
of test probes.
4.11.4 Read the measuring resistance value from LCD display.
4.12 Measurement
When measuring resistance, press FUNC key to switch continuity test.
4.12.1 Respectively connect black and red test probes to COM input socket
and input socket.
4.12.2. Measure the resistance value of circuit to be tested with other two
ends of test probes
4.12.3. During continuity test, if the measured circuit resistance is not
greater than about 50, the buzzer may issue continuous sound.
4.13 Measurement
When measuring continuity, press FUNC key to switch to diode test.
4.13.1 Respectively connect black and red test probes to COM input socket
and input socket.
4.13.2. Measure two ends of diode to be measured with other two ends of
test probes
4.13.3. The meter will display the forward voltage drop value of the diode.
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MS8250A/B Digital Multimeter
Operating guidance
4.14 Capacitance measurement
Capacitance range of this meter: 40.00nF, 400.0nF, 4.000F, 40.00F,
100.0F
To measure capacitance:
4.14.1 Rotate rotary switch to position.
4.14.2 Respectively connect black and red test probe to COM input socket
and input socket.
4.14.3 Measure the capacitance value of circuit to be tested with other two
ends of test probes and read the measuring value from LCD display.
4.15 Frequency and duty ratio measurement
Capacitance range of this meter: 5Hz, 50Hz, 500Hz, 5kHz, 50kHz, 5MHz
To measure capacitance:
4.15.1 Rotate the switch to Hz position.
4.15.2 Respectively connect black and red test probe to COM input socket
and Hz input socket.
4.15.3 Measure the frequency to be measured with other two ends of test
probes and read the measuring value from LCD display.
4.16 Current measurement
Current range of this meter: 400A, 4000A, 40.00mA, 400.0mA,
10.000A;
4.16.1 Cut off the power supply of circuit to be tested. Discharge all high
voltage capacitors on the circuit to be tested.
4.16.2 Rotate switch to the appropriate position (uA, mAor Agrade).
4.16.3 Connect the black test probe to the COM input socket. If the current
to be tested is lower than 600mA, connect the red test probe to the mA input
socket; if the measured current is between the range of 600mA~10A, the
red test probe should be connected to 20A input socket.
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MS8250A/B Digital Multimeter
Operating guidance
4.16.4 Cut off the circuit to be tested. Connect the black test probe to one
end of disconnected circuit (low voltage relatively), and connect the red test
probe to the other end of disconnected circuit (high voltage relatively).
4.16.5. Connect the power supply of circuit to be tested, then read the display
reading. If the display shows only “OL”, the input is out of the selected input
range, so please rotate the switch to a higher measuring range.
4.17 Communicate with computer (only for MS8250B)
One end of USB cable is connected to one end of the meter, the other end is
connected to computer USB interface, at this time, the meter will display
PCLINK, open the special software of this machine to read and save the meter
measuring data.
5. Maintenance
5.1 Replace battery
Warning
Before opening the meter battery cover, remove probe from the
circuit to be measured to avoid electric shock.
5.1.1 When the battery indicator “ ” appears, the battery should be
replaced immediately.
5.1.2 Unscrew the fastening screw of the meter battery cover and remove it .
5.1.3 Replace battery.
5.1.4 Install the battery cover.
Note:
The battery polarity can't be reversed.
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MS8250A/B Digital Multimeter
Attachments
5.2 Replace probe
Warning
When replacing probe, replace with another identical probe or one
with the same capacity. The probe should be in good condition, with
a capacity of 1000V, 10A。
If the probe is damaged, such as having a bare metal wire, it should be
replaced immediately.
6. Accessories
1)
Probe
1 pc
2)
Operation Manual
1 pc
3)
Battery
9V 6F22
1 pc
4)
Interface cable
USB interface cable
(MS8250B)
1 pc
5)
CD
Communication software
CD (MS8250B)
1 pc
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Dongguan Huayi Mastech Co., Ltd
Shenzhen Huayi Mastech Co., Ltd
Address: Floor 9, Block 3 West, Saige Science
& Technology Park, North Huaqiang Road,
Shenzhen City
Tel.: [phone] 0755-83766670
Fax.: [phone]
Post Code: 518028
E-mail: [email protected]
Website: www.mastech.cn
HM0465401