Mastech MS8218 User manual

MS8218 True RMS Multimeter
Contents
Contents
Chapter 1 Safety Information
◎ Meter Safety Standards………………………………………………………………………………………………….
◎ Warning………………………………………………………………………………………………………………….
◎ Limited Guarantee and the Liability Range……………………………………………………………………………..
Chapter 2 Introduction to the Meter
◎ Characteristics………………………………………………………………………………………….……………..…
◎ Explanation on Front Panel……………………………………………………………………………………………...
◎ Understanding Display Screen…………………………………………………………………………………………..
◎ Function Descriptions……………………………………………………………………………………..…………….
Chapter 3 Operation Methods
◎ ACV/dBm Measurement…………………………………………………………………………………………………
◎ DCV/DCV+ACV Measurement…………………………………………………………………………………………
◎ DC mV/AC mV /DC mV+AC mV Measurement……………………………………………………………………….
◎ Logic Frequency/Duty Ratio Measurement……………………………………………………………….…………….
◎ Diode Measurement……………………………………………………………………………………………………..
◎ Resistance/continuity Measurement…………………………………………………………………………………….
◎ Capacitance Measurement………………………………………………………………………………………………
◎ DC μ A /AC μ A/DC μ A +AC μ A Measurement…………………………………………………………………
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MS8218 True RMS Multimeter
Contents
◎ DC mA/AC mA/DC mA +AC mA Measurement……………………………………….………………………………
◎ DC Ampere/AC Ampere/DC Ampere+AC Ampere Measurement……………………….…………………………….
◎ Linear Frequency Measurement……………………………………….…………….……………….………..…………
◎ Relative Value Measurement………………………………………………………….…………………………………
◎ Maximum Value/Minimum Value/Maximum Value-Minimum Value Measurement………………………….………
◎ Backlight Control……………………………………………………………………………………………….……….
◎ Data Hold………………………………………………………………………………………………………………..
◎ Automatic Shutdown and Continuous Operation Mode Selection………………………………………………………
◎ Connected to RS-232C Interface Of Computer…………………………………………………………………………
Chapter 4 Technological Specifications
◎ General Features…………………………………………………………………………………………………………
◎ Range and Accuracy……………………………………………………………………………………………………..
Chapter 5 Maintenance
◎ Replacement of Batteries………………………………………………………………………………………………..
◎ Replacement of Fuse…………………………………………………………………………………………………….
◎ Meter Calibration………………………………………………………………………………………………………..
◎ Others ………………………………………………………………………….………..………………………………
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MS8218 True RMS Multimeter
Safety Information
Chapter 1
Meter Safety Standards
This style of digital multimeter is designed and manufactured according to the safety requirements set out by the IEC1010-1
standards for electronic test instruments and the hand-hold digital multimeters. Its design and manufacture is strictly based on
the provisions in the 1000V CAT
Ⅲ of IEC1010-1 and the Stipulation of 2-Pollution Grade.
The meter conforms to the European Union’s following requirements:89/336/EEC
(EMC Electromagnetic Compatibility ),73/23/EEC(LVD Low Voltage Protection)and 93/68/EEC(CE Mark).
Warning
Before use of the meter firstly check up if there is any crack on the outer shell or if it lacks any plastic part, and check up
whether the testing line is damaged or has any exposed metal. The meter can be used only if no any insulating problem be
found.
Carefully read the operating methods and safety prompts in this manual. Using it not based on the methods specified in
this manual may cause the meter damaged.
Non-normal meter must not be used. It should be sent for repairing.
The meter must not be used in an environment with combustible gases, steam or dust pollution.
It should be careful to work when measuring votage higher than 30Vac(effective value)or 50Vdc for such voltage having
the risk of shock. Avoid the body directly touching ground or any metal substance in which there may be ground
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MS8218 True RMS Multimeter
Safety Information
potential during measuring. The body should be kept insulated from ground with dry insulating shoes, insulating pads or
insulating clothes.
When performing measurement with a test probe your fingers should be put behind a finger-protector.
Must not try to measure a voltage higher than 1000VAC or 1000VDC,the meter may be damaged and the operator’s safety
may be threatened if the limit for voltage measurement be exceeded.
when the symbol for electric insufficiency appearing on the display screen it is necessary to replace the batteries for
avoiding the possible shock or injure resulted in by erroneous reading.
In case of replacing batteries, it is necessary firstly to pull out the testing line. AA batteries should be used and they should
be put into the meter with the proper polarity.
Must not make any voltage measurement when the testing line being inserting into the current hole.
Repair and calibration of the meter must be carried out by experienced professionals, unprofessionals should not repair and
calibrate the meter by themselves.
Limited Guarantee and the Liability Scope
This company will undertake repairs freely for any quality problem of the meter which if should be found within 18 months
from the date at which it was bought, but which not including replacement of fuse and batteries as well as any damage caused
by negligence, wrong use, pollution, change of circuit and non-normal use.
For maintenance beyond the 18-month guarantee period, the company will charge a certain repair fee and materials cost.
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MS8218 True RMS Multimeter
Introduction to the Meter
Chapter 2
Characteristics
50000 counts measurement
ACV and DCV measurements reach up to 1000V.
DC measurement accuracy reaches up to 0.03%.
0.01
Ω resistance resolution and 1 μ V voltage resolution.
Linear frequency measurement, logic frequency/duty ratio measurement.
Capacitance measurement from 0.01nf to 5000 μ F.
AC/DC true RMS measurement.
DBm measurement
Maximum value/minimum value measurement, Relative measurement.
50-segment analog bar display.
Automatic shutdown/continuous working mode selection.
Back light control.
RS-232C infrared interface.
Display, record and graphics software of computer.
Overload protection.
Sound alarm for wrong current measurement.
Secondary plasticizing meter shell, with insulating performance reaching 1000V CAT Ⅲ
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MS8218 True RMS Multimeter
Introduction to the Meter
Explanation on Front Panel
The front panel is shown as in Figure 2-1,
explanation being as follows:
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MS8218 True RMS Multimeter
Introduction to the Meter
(1) V Ω Hz end
It is the input end for all measurement functions except for current measurement, connected with a red meter probe.
(2) COM end
It is the negative input end for all measurements, connected with a black meter probe.
(3)µA/mA end
It is the positive end for measurement of µA or mA current, connected with a red meter probe.
(4)A end
It is the positive input end for measurement of 0.5A-10A current, connected with a red meter probe.
(5)Rotary switch
Used for selecting measurement functions such as voltage, current, resistance and Capacitance.
(6)POWER switch
Used for putting on or off the operating power for the meter.
(7)RANGE key
For various kinds of measurements it is used manually to select range. Under the automatic range state (AUTO displaying), it
will enter manual range state(MANUAL displaying) with a press on RANGE, after that the range will be changed with a press
on RANGE while the small digits on the left lower corner indicating the actual range. When the RANGE key being released
after pressing for two seconds the meter will return back to the automatic state. When performing logic frequency measurement
and diode measurement pressing RANGE will be void. During dBm measurement, pressing RANGE key will alter the virtual
resistance value for calculating dBm.
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MS8218 True RMS Multimeter
Introduction to the Meter
(8) SELECT key
When setting the rotary switch to a measurement function, the meter will enter its first measurement mode, while pressing the
SELECT key it is possible to select the second or the third measurement mode. However, there is only one for the diode and
Capacitance measurements.
(9)WAKE key
After the meter being automatically shutdown, by pressing the WAKE key it can be woken up to resume the measurement. In
case of pressing POWER switch(for putting on the unit) and WAKE key simultaneously, the meter will in a continuously
working state without the automatic shutdown function.
(10)MAX/MIN key
Press MAX/MIN key to enter the record state for the maximum and minimum value and simultaneously display the maximum
value. By pressing this key again it will be possible to display the minimum value and the maximum value-minimum value.
When releasing the key after pressing it for two seconds, the maximum and minimum record state will be exited. Pressing this
key will be void during frequency
、 diode measurement.
(11)REL △ key
By pressing REL △ to enter the relative measurement state, the meter will remember the value measured at the time when
pressing the key(it is called the initial value), and after that the value displayed in the meter will be equivalent to the present
value – the initial value. By pressing the key again the relative measurement state will be exited. Pressing the key will be void
during the frequency and diode measurements.
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MS8218 True RMS Multimeter
Introduction to the Meter
(12)HOLD key
Used to maintain the measurement data unchanging, by pressing the key again it will resume the measurement. When
releasing the key after pressing it for two seconds, the meter will enter the state connecting with the RS-232C interface of
computer while sending measurement information to computer. When releasing the HOLD key after pressing it for two seconds
again, it will stop to send data to the RS-232C interface.
(13)LIGHT key
By pressing this key for a time, the backlight of the LCD screen will be opened and after five seconds the meter will
automatically turn off the backlight. It is also possible to turn off the backlight by pressing the LIGHT key before the five
seconds.
(14)
～
～～
～ Hz key
During the voltage or current measurements, by pressing ～ Hz key the meter will enter the linear frequency measurement
state. At this time what being measured is the frequency of voltage or current. By pressing this key again it will exit the linear
frequency measurement state.
(15)LCD screen
Used for displaying the measuring results and various symbols.
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MS8218 True RMS Multimeter
Introduction to the Meter
Understanding Display Screen :
Figure 2—2
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MS8218 True RMS Multimeter
Introduction to the Meter
LCD screen is shown as in Figure 2-2, with its every symbol’s meaning shown as in the Table 1:
Number of Order Symbol Functions
1
℃
℃℃
℃ ℉
℉℉
℉ Indicating the measurement unit being
℃ or ℉ of temperature
1 mnF Indicating the measurement unit being
μ F or nF of Capacitance
1 m
μ
μμ
μ A Indicating the measurement unit being
μ A,mA or A of current
1 dBmV Indicating the measurement unit being dBm of power or mV and V of voltage
1 MK
Ω
ΩΩ
Ω Hz Indicating the measurement unit being M
Ω ,K Ω and Ω of resistance or
MHz, KHz and Hz of frequency
2
Indicating the measurement unit being the duty ratio of logic impulse
3 MAX-MIN Indicating the display value being the maximum value(MAX),the minimum
value(MIN) or the maximum value-the minimum value(MAX-MIN)
4 AUTO Indicating the measurement being automatic range
5 MANUAL Indicating the measurement being manual range
6 51000 Indicator of range, indicating the full range value of this range in manual
range such as 5, 50, 500 and 1000,5000, etc.
7
Indication to low voltage of the batteries, showing the energy of batteries will
be exhausted soon
8
Indicating the measurement being relative measurement while the displayed
value being relative value
9 Indicating it is now performing the continuity measurement
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MS8218 True RMS Multimeter
Introduction to the Meter
Tabel1 (continue)
10
AC
Indicating it is now in the AC measurement state, while DC and AC
displaying simultaneously, indicating it is DC+AC measurement
11 Indicating the measurement vale being negative
12
DC
Indicating it is now in the DC measurement state, while DC and AC
displaying simultaneously, indicating it is DC+AC measurement
13
Indicating it is now in the data-holding state
14
Please Wait ...
When measuring 50 μ F ～ 5000 μ F capacitor under automatic range, for
ensuring the accuracy of measurement, it is necessary to perform the
measurement after fully discharging capacitor while prompting the
operator to wait
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Analog bar, indicating the measurement value with a graphic mode
16
Indicating the meter being in the state for sending data to the RS-232C
interface of computer
17
The display zone for the meter’s measurement value, showing all the
measurement values
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MS8218 True RMS Multimeter
Introduction to the Meter
Function Descriptions
Along with the conventional measurement functions this meter also possesses some special functions which being described as
follows:
● True effective value (TRUE RMS) measurement: all the measurement values of this meter on the AC voltage and AC
current are true effective values, which distinguishing this meter from the low-grade meters which only can measure the AC
average value.
● dBm measurement: dBm measurement is a value calculated and displayed under the current AC voltage, with a virtual
resistance R obtained through RANGE key and according to the following formula:
It is the AC power expressed in the logarithmic form.
● DC+AC measurement: when measuring voltage or current having both the AC and the DC components, in case of selecting
the DC+AC measurement mode, this meter will perform measurements on both DC and AC components respectively and
then calculate and display the results according to the following formula:
DC+AC measurements reflect the general effective values generated jointly by both the DC and AC components.
● Automatic and manual ranges: When turning on the meter’s power switch the meter defaults the automatic range
state(AUTO displaying), and simultaneously it will automatically select the proper range according to the measured electric
parameters. If OL being displayed under automatic range, it indicates the measured value exceeding the meter’s maximum
range. Pressing the RANGE key under the automatic range the meter will enter the manual range(MANUAL displaying),
then pressing the RANGE key again it will be possible to select the required range. The indicator for range will display the
maximum value of this range. If OL displaying under the manual range, it indicates the measured value exceeding the
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MS8218 True RMS Multimeter
Introduction to the Meter
selected range. Press the RANGE key under the manual range for two seconds and then release it, the meter will go back to
the automatic range state.
● Linear frequency measurement: Pressing the ～ Hz key when the meter performing measurements on AC voltage or current
as well as on mixture signal of AC and DC, it will be capable to measure the frequency of the AC component. However it
has a certain requirements on the amplitude of the AC component.
● Logic impulse duty ratio measurement: logic impulse duty ratio refers to ： (high level width/impulse cycle) × 100%
● Diode measurement: during diode measurement the meter is indicating to the forward voltage drop of the diode
● Relative measurement: during relative measurement the meter remembers internally the instantaneously measured
value(called initial value)when pressing the REL Δ key, and the later displaying value being:
present value – initial value
The relative measurement value reflects the changes of the measured value. It also can be used to take off the errors
brought about by lead resistance or distributed capacitance during measuring low resistance and low capacitance. Due to
subtraction calculation, negative value may appear during measuring AC current, resistance and capacitance.
● Maximum/minimum value measurement: by pressing MAX/MIN keys the meter can enter the maximum/minimum value
record state, and it will continuously update the maximum/minimum values based on the new measurement results. Pressing
the MAX/MIN key can display the maximum value, the minimum value and the maximum value-the minimum value in
cycles. After exiting the MAX/MIN measurement state the recorded maximum value/minimum values will disappear.
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MS8218 True RMS Multimeter
Introduction to the Meter
● Automatic shutdown and the continuous operating mode: after the meter being turned on, in case of stopping to pressing
any key or stopping to turning the rotary switch for more than fifteen minutes, the meter will automatically shutdown. As
the meter will still consume a little energy after its automatic shutdown, so it is better to turn off the POWER switch if the
meter remains idle for a long time. If you want the meter to operate continuously without automatically turning off, it can be
done only just by pressing down the WAKE key at the same time when turning on the POWER switch.
● Low voltage detection: when the meter detecting the total voltage of the batteries lower than 6.8V, the symbol on the
LCD screen will be lighted to prompt the batteries should be replaced.
● Analog indication bar: analog indication bar is used for graphic measurement value and it always synchronizes with the size
of the present measured value. During the maximum value/minimum value measurement and the relative value
measurement it sill synchronizes with the size of the present measured value, and not indicating the maximum
value/minimum value or the relative value.
● RS-232C interface: press the HOLD key for two seconds and then release it, the meter will open the infrared interface for
sending the measured data and status to the RS-232C interface of computer. Equipped with record and graphic software
(options)the meter can display, record and describe the measured electric quantity on computer. As the data transmission
between the meter and computer is depending on light coupling, so measurement of high voltage will not affect the safety
of computer.
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MS8218 True RMS Multimeter
Operation Methods
Chapter 3 Operation Methods
ACV/dBm Measurement
The measurement is shown as in Figure 3-1, with voltage range being of AC 0.5V ～ 1000V and the measurement methods
being as follows:
1. Turn on the power switch and set the rotary switch to the position of V
～ /dBm .
2. Insert the red and black testing lines into V Ω
ΩΩ
Ω Hz end and COM end respectively.
3. Select the ACV or dBm measurement mode with the SELECT key.
4. Connect the meter to the two ends of the measured voltage with the red and black probes.
5. Read the meter’s data from the display screen. When OL displaying on the meter, it indicates the measured voltage
exceeding the meter’s range and it is necessary to remove both the red and black probes from the measured circuit
immediately.
6. By pressing the RANGE key it is possible to select range manually. Indicator of range displays range. While displaying
OL during manual range measurement, it is necessary to select a larger range. When OL displaying under the maximum
range, it indicates the voltage exceeding 1000V,so it is necessary to remove both the red and black probes from the
measured circuit immediately.
7. To perform dBm measurement, press the RANGE key to select the resistance value needed for calculating dBm,there are
4,8,16,32,50,75,93,110,125,135,150,200,250,300,500,600,800,900,1000 and 1200 ohms being possible to be selected
respectively.
Notes: in case of probe hanging in the air, the voltage inducted by the testing line may cause unstable readings on the display
screen, but that will not affect the accuracy of measurement.
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MS8218 True RMS Multimeter
Operation Methods
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ACV/dBm Measurement
Figure 3-1
Warning
Not try to measure
a voltage higher then
1000 vol t

MS8218 True RMS Multimeter
Operation Methods
DCV/DCV + ACV Measurement
The measurement is shown in Figure 3-2,the range of voltage is of AC or DC 0.5V ～ 1000V and the methods are as follows:
1. Turn on the power switch and set the rotary-table switch to the position V.
2. Insert the red testing line into the V Ω
ΩΩ
Ω Hz end and the black testing line into the COM end.
3. Press SELECT key to select DCV or DCV + ACV measurement mode.
4. When performing DCV measurement, connect the red probe to the positive polarity of the measured voltage and the
black probe to the negative polarity of the measured voltage. While performing DCV + ACV measurement, it will be
done by connecting the red probe and the black probe into the two ends of the measured voltage.
5. Read the measured value from the display screen. If OL displaying on the meter, it indicates the measured voltage
exceeding the range of the meter and it is necessary to remove the both red and black probes from the measured circuit
immediately.
6. When performing DCV measurement, by pressing the RANGE key it is possible to select range manually. The
indicator of range indicates the range value. If OL displaying during manual range measurement, it is necessary to
select a larger range. If OL displaying under the maximum range, it indicates the voltage exceeding 1000V and it is
necessary to remove the both red and black probes from the measured circuit immediately.When performing DCV +
ACV measurement automatic range will be held and it is null to press the RANGE key.
Notes: in case of probe hanging in the air, the voltage inducted by the testing line may cause unstable readings on the
display screen, but that will not affect the accuracy of measurement. When performing DCV + ACV measurement it will be
relatively slow to refresh the measured data as it needs time to switch AC and DC measurements and to calculate RMS.
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MS8218 True RMS Multimeter
Operation Methods
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DCV
DCV + ACV Measurement
Figure 3-2
Warning
Not try to measure
a voltage higher then
1000 vol t

MS8218 True RMS Multimeter
Operation Methods
DC mV/AC mV/DC mV+AC mV Measurement
The testing chart is shown in the Figure 3-3. The voltage measurement range is of 1 μ V ～ 500mV and the measurement
methods are as follows:
1. Turn on the power switch and set the rotary switch to the position mV .
2. Insert the red testing line into the V
Ω
ΩΩ
Ω Hz end and the black testing line into the COM end.
3. Press the SELECT key to select DCmV or AcmV or DCmV + AcmV measurement modes.
4. When performing DCmV measurement, connect the red probe to the positive polarity of the measured voltage and the
black probe to its negative polarity. While performing ACmV or DCmV+ ACmV measurement, it will be done by
connecting the red probe and the black probe into the two ends of the measured voltage.
5. Read the measured value from the display screen. If OL displaying on the meter, it indicates the measured voltage
exceeding the range of the meter and it is necessary to remove both the red and black probes from the measured circuit
immediately.
6. When performing DCmV or ACmV measurement, by pressing the RANGE key it is possible to select range manually.
The indicator of range indicates the range value. If OL displaying during manual range measurement, it is necessary to
select a larger range. If OL displaying under the maximum range, it is necessary to remove both the red and black
probes from the measured circuit immediately. When performing DCmV + ACmV measurement automatic range will
be held and it is void to press the RANGE key.
Notes: In case of probe hanging in the air, the voltage inducted by the testing line may cause unstable readings on the
display screen, but that will not affect the accuracy of measurement.When performing DCmV + ACmV measurement it will
be relatively slow to refresh the measured data as it needs time to switch AC and DC measurements and to calculate RMS.
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