Witam! Nie mogę poradzić sobie z wyborem multimetru w klasie cenowej 500-600zł. Znalazłem dwa multimetry (w tytule) godne uwagi. O firmie Brymen słyszałem dużo pozytywnych opinii, ale ten VA38 ma sporo lepszą dokładność. Może ktoś poleci jeszcze jakiś model jego zdaniem godny uwagi? Noty mierników w załączniku! BM857a - 505zł. VA38 - 550zł. Zauważyłem jeszcze, że VA38 jest bardzo podobny do Mastecha MS8218. Nie ma też informacji o współczynniku szczytu odnośnie pomiaru TrueRMS.
VA38 True RMS Multimeter
Contents
Contents
Chapter 1
Safety Information
◎ Meter Safety Standards…………………………………………………………………………………………………. 1
◎ Warning…………………………………………………………………………………………………………………. 1
◎ Limited Guarantee and the Liability Range…………………………………………………………………………….. 2
Chapter 2
Introduction to the Meter
◎ Characteristics………………………………………………………………………………………….……………..… 3
◎ Explanation on Front Panel……………………………………………………………………………………………... 4
◎ Understanding Display Screen………………………………………………………………………………………….. 8
◎ Function Descriptions……………………………………………………………………………………..……………. 11
Chapter 3
Operation Methods
◎ ACV/dBm Measurement…………………………………………………………………………………………………14
◎ DCV/DCV+ACV Measurement………………………………………………………………………………………… 16
◎ DC mV/AC mV /DC mV+AC mV Measurement………………………………………………………………………. 18
◎ Logic Frequency/Duty Ratio Measurement……………………………………………………………….……………. 20
◎ Diode Measurement…………………………………………………………………………………………………….. 22
◎ Resistance/continuity Measurement……………………………………………………………………………………. 24
◎ Capacitance Measurement……………………………………………………………………………………………… 26
◎ DC μA /AC μA/DC μA +AC μA Measurement………………………………………………………………… 28
I
VA38 True RMS Multimeter
Contents
◎ DC mA/AC mA/DC mA +AC mA Measurement……………………………………….……………………………… 30
◎ DC Ampere/AC Ampere/DC Ampere+AC Ampere Measurement……………………….……………………………. 32
◎ Linear Frequency Measurement……………………………………….…………….……………….………..………… 34
◎ Relative Value Measurement………………………………………………………….………………………………… 35
◎ Maximum Value/Minimum Value/Maximum Value-Minimum Value Measurement………………………….……… 35
◎ Backlight Control……………………………………………………………………………………………….………. 36
◎ Data Hold……………………………………………………………………………………………………………….. 36
◎ Automatic Shutdown and Continuous Operation Mode Selection……………………………………………………… 36
◎ Connected to RS-232C Interface Of Computer………………………………………………………………………… 37
Chapter 4
Technological Specifications
◎ General Features………………………………………………………………………………………………………… 38
◎ Range and Accuracy…………………………………………………………………………………………………….. 39
Chapter 5
Maintenance
◎ Replacement of Batteries……………………………………………………………………………………………….. 43
◎ Replacement of Fuse……………………………………………………………………………………………………. 43
◎ Meter Calibration……………………………………………………………………………………………………….. 44
◎ Others ………………………………………………………………………….………..……………………………… 44
II
VA38 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 CATⅢ 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).
l
l
l
l
l
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
1
VA38 True RMS Multimeter
Safety Information
l
l
l
l
l
l
l
l
l
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.
Keep batteries out of reach of children.
If a battery leaks, remove all batteries,taking care to keep the leaked fluid fromtouching your skin or clothes. If fluid from
the battery comes into contact with skin or clothes, flush skin with water immediately.Before inserting new batteries,
thoroughly clean the battery compartment with a damp paper towel, or follow the battery manufacturer’s recommendations
for cleanup.
Dispose of batteries in accordance with local and national disposal regulations, including those governing the recovery and
recycling of waste electrical and electronic equipment (WEEE).
Do not heat, open, puncture, mutilate, or dispose of batteries in fire.
VA38 True RMS Multimeter
Safety Information
l
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.
2
Chapter 2
Characteristics
l 50000 counts measurement
l ACV and DCV measurements reach up to 1000V.
l DC measurement accuracy reaches up to 0.03%.
l 0.01 Ω resistance resolution and 1μV voltage resolution.
l Linear frequency measurement, logic frequency/duty ratio measurement.
l Capacitance measurement from 0.01nf to 5000μF.
l AC/DC true RMS measurement.
VA38 True RMS Multimeter
Introduction to the Meter
l
l
l
l
l
l
l
l
l
l
DBm measurement
Maximum value/minimum value measurement, Relative measurement.
50-segment analog bar display.
Automatic shutdown/continuous working mode selection.
Back light control.
PC-LINK: 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 CATⅢ
3
Explanation on Front Panel
The front panel is shown as in Figure 2-1,
explanation being as follows:
15
10
Figure 2-1
14
9
13
8
7
6
12
dBm-
%
Hz
PCLINK
True RMS
AC+DC
11
VA38 True RMS Multimeter
Introduction to the Meter
4
(1) VΩHz 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.
VA38 True RMS Multimeter
Introduction to the Meter
(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.
5
(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
VA38 True RMS Multimeter
Introduction to the Meter
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.
6
(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 PC-LINK 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.
VA38 True RMS Multimeter
Introduction to the Meter
(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.
7
Understanding Display Screen :
15
14
13
12
11
10
9
16
17
1
VA38 True RMS Multimeter
Introduction to the Meter
Figure 2—2
8
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
Indicating the measurement unit being ℃ or ℉ of temperature
1
℃ ℉
1
mnF
Indicating the measurement unit being μF or nF of Capacitance
1
mμA
1
dBmV
Indicating the measurement unit being μA,mA or A of current
Indicating the measurement unit being dBm of power or mV and V of voltage
1
MKΩHz
2
Indicating the measurement unit being MΩ,KΩand Ω of resistance or
MHz, KHz and Hz of frequency
Indicating the measurement unit being the duty ratio of logic impulse
VA38 True RMS Multimeter
Introduction to the Meter
3
AUTO
4
MANUAL
5
51000
6
MAX-MIN
7
REL
8
9
AC
Indicating the measurement being automatic range
Indicating the measurement being manual range
Indicator of range, indicating the full range value of this range in manual
range such as 5, 50, 500 and 1000,5000, etc.
Indicating the display value being the maximum value(MAX),the minimum
value(MIN) or the maximum value-the minimum value(MAX-MIN)
Indicating the measurement being relative measurement while the displayed
value being relative value
Indicating it is now performing the continuity measurement
Indicating it is now in the AC measurement state, while DC and AC
displaying simultaneously, indicating it is DC+AC measurement
9
Tabel1 (continue)
Indicating the measurement vale being negative
10
11
DC
Indicating it is now in the data-holding state
12
13
Indicating it is now in the DC measurement state, while DC and AC
displaying simultaneously, indicating it is DC+AC measurement
Please Wait ...
When measuring 50μF～5000μF capacitor under automatic range, for
ensuring the accuracy of measurement, it is necessary to perform the
measurement after fully discharging capacitor while prompting the
VA38 True RMS Multimeter
Introduction to the Meter
operator to wait
14
15
16
Indication to low voltage of the batteries, showing the energy of
batteries will be exhausted soon
Analog bar, indicating the measurement value with a graphic mode
Indicating the meter being in the state for sending data to the RS-232C
interface of computer
The display zone for the meter’s measurement value, showing all the
measurement values
17
10
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:
VA38 True RMS Multimeter
Introduction to the Meter
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
11
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
VA38 True RMS Multimeter
Introduction to the Meter
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.
12
● 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
the LCD screen will be lighted to prompt the batteries should be replaced.
symbol on
● 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.
VA38 True RMS Multimeter
Introduction to the Meter
● PC-LINK (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.
13
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:
dBm
1. Turn on the power switch and set the rotary switch to the position of V .
2. Insert the red and black testing lines into VΩHz 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
VA38 True RMS Multimeter
Operation Methods
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.
14
ACV/dBm Measurement
V
Warning
Not try to measure
dBm-
PCLINK
a voltage higher then
DCV/DCV + ACV Measurement
%
Hz
True RMS
AC+DC
uA
1000 volt
15
VA38 True RMS Multimeter
Operation Methods
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 VΩHz 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.
16
DCV
VA38 True RMS Multimeter
Operation Methods
Warning
Not try to measure
a voltage higher then
1000 volt
17
DC mV/AC mV/DC mV+AC mV Measurement
VA38 True RMS Multimeter
Operation Methods
The testing chart is shown in the Figure 3-3. The voltage measurement range is of 1μV～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 VΩHz 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.
18
DC mV/AC mV
VA38 True RMS Multimeter
Operation Methods
19
Logic Frequency/Duty Ratio Measurement
VA38 True RMS Multimeter
Operation Methods
The testing chart is shown in the Figure 3-4.The frequency range is of 5Hz～2MHz（Vp 2.5～5V）,while the duty ratio
measurement range being of 5%～95%.And the measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position Hz% .
2. Insert the red testing line into the VΩHz end and the black testing line into the COM end.
3. Press the SELECT key to select the logic frequency(Hz) or duty ratio( % ) modes.
4. Connect the red testing line to high logic level, the black one to low logic level.
5. Read the measured value from the display screen. If the frequency of the measured signal is lower or higher than the
meter’s measurement range, the reading will be displayed as zero. If the amplitude of signal is too low or the low level
is larger than 1 volt, the reading will also displayed as zero.
6. This measurement is of automatic range, it is null to press the RANGE key.
20
Logic Frequency
VA38 True RMS Multimeter
Operation Methods
21
Diode Measurement
VA38 True RMS Multimeter
Operation Methods
The measurement chart is shown in figure 3-5. The measurement range of diode is of 0～2.5V.
The measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position
.
2. Insert the red testing line into the VΩHz end and the black testing line into the COM end.
3. Connect the red probe to the positive polarity of the diode and the black probe to its negative polarity, while the
display screen will display the forward voltage drop.
4. Connect the black probe to the positive polarity of the diode and the red probe to its negative polarity, if OL displaying
on the display screen, it indicates the backward resistance of the diode being normal, while OL not displaying, it
indicates that the diode is backward leaking.
Notes: In case of performing diode test on circuit board, it is necessary firstly to turn off the power of the circuit board and
then perform the measurement. As there may be other parallel circuits, so the displayed value of test is not surely the results
listed in items 3 and 4.
22
Diode Measurement
VA38 True RMS Multimeter
Operation Methods
23
Resistance/continuity Test
VA38 True RMS Multimeter
Operation Methods
The test chart is seen in Figure 3-6. the measurement range of resistance is of 0.01Ω～50MΩ and the measurement
methods are as follows:
1. Turn on the power switch and set the rotary switch to the position
.
2. Insert the red and black testing lines into the VΩH input end and the COM input end respectively.
) modes.
3. Press the SELECT key to select resistance (Ω) or the continuity (
4. For the resistance measurement, connect the red and black probes to the two ends of resistor and read the resistance
value from the display screen. If OL displaying, it indicates the resistor is larger than 50MΩ. As for the continuity
measurement, connect the red and black probes to the two measured points respectively. In case of the resistance
between the two points being less than about 50Ω∽60Ω, the buzzer will sound while the display screen displaying the
value of resistance. If OL displaying, it indicates the resistance between the two points is larger than 500Ω.
5. When the resistance measurement mode being implemented, it is possible to select range by pressing the RANGE key.
The indicator of range indicates the value of range. If OL displaying during manual range measurement, it is necessary
to select a larger range. Under the continuity measurement mode it is null to press the RANGE key.
Notes: In case of performing resistance or continuity test on circuit board, it is necessary firstly to turn off the power of the
circuit board and then perform the measurement. As there may be other parallel circuits, so the displayed value of test is not
surely the actual value of the resistor.
24
VA38 True RMS Multimeter
Operation Methods
25
Capacitance Measurement
VA38 True RMS Multimeter
Operation Methods
The measurement chart is seen in figure 3-7. the measurement range of capacitance is of
10PF～5000μF and the measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position
.
2. Insert the red and black testing lines into the VΩHz input end and the COM input end respectively.
3. If exists voltage in the capacitor, connect the two ends of the capacitor for a short time to discharge.
4. Connect the red and black probes to the two ends of the capacitor, if the measured capacitor is heteropolar, it is
necessary to connect the red probe to the positive polarity of the capacitor and the black probe to its negative polarity.
5. Read the capacitance from the display screen. If capacitance value & gt; 5300μF, the meter will display OL, while
capacitance value & lt; 10PF,it will display zero.
6. It is possible to select range manually by pressing the RANGE key. The indicator of range indicates the value of range.
If OL displaying during manual range measurement, it is necessary to select a larger range.If it has been the largest
range, which means capacitance value & gt; 5300μF.
Notes: When performing measurement on 500μF—5000μF capacitor, in order to ensure measurement accuracy the meter
takes a relative long time to discharge capacitor, so it is relatively slow in refreshing the measured value. In addition,not to
perform Capacitance measurement on a circuit board on which there are other parallel devices, for that may leads to very
large error.
26
Capacitance Measurement
VA38 True RMS Multimeter
Operation Methods
27
VA38 True RMS Multimeter
Operation Methods
DC μA/AC μA /DC μA+ AC μA Measurement
The measurement is seen in Figure 3-8, the measurement range of current is of AC or DC 0.01μA～5000μA , and the
measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position
.
2. Insert the red testing line into the mA/μA input end and the black testing line into the COM input end.
1. Press the SELECT key to select the DcμA, AcμA or the DcμA + AcμA measurement modes.
2. Turn off the power of the measured circuit, connect the red and black probes to the measured circuit in serial way and
then turn on the power of the measured circuit.
3. Read the measured value from the display screen. If it displays as positive during the DC measurement, it means the
current is flowing into the meter from the red testing line, while it displaying as negative, it means the current is
flowing into the meter from the black testing line. If it displays as OL, it means current exceeding range.
4. During measurement of DC μA or AcμA， is possible to select range manually by pressing the RANGE key. Under
it
the DCμA + AcμA measurement mode, automatic range is held and it is null to press the RANGE key.
Notes: Under the DCμA + ACμA measurement mode, it is relatively slow to refresh the measured data as it is needs time
to switch AC and DC measurements and to calculate RMS.
28
VA38 True RMS Multimeter
Operation Methods
DC μA
i
i
AC μA
DC μA+AC μA
Measurement
PCLI NK
dBm-
True RMS
AC+DC
%
Hz
uA
mV
V
mA
dBm
A
V
dBm Hz
VA38 DMM
A
uA mA
10A MAX
10SEC. MAX
V mV
COM
100
Figure 3-8
29
VA38 True RMS Multimeter
Operation Methods
DC mA/AC mA /DC mA + AC mA Measurements
The measurement is seen in the Figure 3-9. The measurement range of current is of AC or DC 1 μA～500mA and the
measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position mA .
2. Insert the red testing line into the mA/μA input end and the black testing line into the COM input end.
3. Press the SELECT key to select the DC mA, AC mA or the DC mA + AC mA measurement modes.
4. Turn off the power of the measured circuit, connect the red and black probes to the measured circuit in a serial way and
then turn on the power of the measured circuit again.
5. Read the measured value from the display screen. If it displays as positive during DC measurement, it means the current is
flowing into the meter from the red testing line, while it displays as negative, it means the current is flowing into the meter
from the black testing line. If it displays OL, indicating current exceeding range.
6. When performing DC mA or AC mA measurement, it is possible to select range manually by pressing the RANGE key.
Under the DC mA + AC mA measurement mode the automatic range is held and it is null to press the RANGE key.
Notes: Under the DC mA + AC mA measurement mode, it is relatively slow to refresh the measured data as it needs time to
switch AC and DC measurements and to calculate RMS.
30
VA38 True RMS Multimeter
Operation Methods
DC mA
i
i
AC mA
DC mA+AC mA
Measurement
PCLINK
dBm-
True RMS
AC+DC
%
Hz
uA
mV
V
mA
dBm
A
V
dBm Hz
VA38 DMM
A
uA mA
10A MAX
10SEC. MAX
V mV
COM
100
Figure 3-9
31
VA38 True RMS Multimeter
Operation Methods
DC Ampere/AC Ampere/DC Ampere + AC Ampere Measurement
The measurement is seen in Figure 3-10, the measurement range of current is of AC or DC 0.1mA～10A and the
measurement methods are as follows:
1. Turn on the power switch and set the rotary switch to the position A .
2. Insert the red testing line into the A input end and the black testing line into the COM input end.
3. Press the SELECT key to select the DC A, AC A or DC A + AC A measurement modes.
4. Turn off the power of the measured circuit, connect the red and black probes to the measured circuit in a serial way and
then turn on the power of the measured circuit again.
5. Read the measured value from the display screen. During the DC measurement, if it displays as positive, it means the
current is flowing into the meter from the red testing line, while it displays as negative, it means the current is flowing into
the meter from the black testing line. If it displays OL, it indicates current exceeding range.
6. When performing DC A or AC A measurement, it is possible to select range manually by pressing the Range key. Under
the DC A + AC A measurement mode, automatic range is held and it is null to press the RANGE key.
Notes: Under the DC A + AC A measurement mode, it is relatively slow to refresh the measured data as it is needs time to
switch AC and DC measurements and to calculate RMS.
32
VA38 True RMS Multimeter
Operation Methods
DC Ampere
i
i
AC Ampere
DC Ampere+AC Ampere
Measurement
PCLINK
dBm-
True RMS
AC+DC
%
Hz
uA
mV
V
mA
dBm
A
V
dBm Hz
VA38 DMM
A
uA mA
V mV
COM
500mA MAX
10SE
100
Figure 3-10
33
VA38 True RMS Multimeter
Operation Methods
Linear Frequency Measurement
The measurement is seen in the Figures 3-1, 3-2, 3-3,3-8 and 3-9. The measurement range is of 5Hz～200KHz and the
measurement methods are as follows:
1. When performing voltage or current measurement, in case of measured value being AC or including AC elements, it is
possible to measure and display the alternating frequency by pressing the ～Hz key. However it has a certain
requirements for the amplitude of alternating signal and the meter has varied requirements for signal amplitude when it is
in different ranges, for information of which please refer to Table 3—1.
2. If the position of rotary switch is in ACV or DCV, after pressing ～Hz key the indicator of range will indicates the
meter’s present voltage range. In addition, it is possible to change the range by pressing the RANGE key to meet the
different voltages.
3. Press ～Hz key again to exit linear frequency
Table 3-1
Range
Sensibility(sine wave)
500mV
100mV
5V
0.5V
50V
4V
500V
40V
1000V
400V
1mA
5000μA
500mA
100mA
Notes: During ampere measurement, due to the very small sample resistor, and the very weak frequency signal produced, so
only when current reaching as large as over 5A can the frequency be measured.
34
VA38 True RMS Multimeter
Operation Methods
Relative Value Measurement
Except for frequency、duty ratio and diode measurements, all other measurements can employ relative measurement. Press
RELΔ key to enter relative measurement and the meter will record the initial value when pressing the key. And the later
displayed value is:
Displayed value = present measurement value — Initial value
Press RELΔagain to exit relative measurement. Changes of measurement value may be found in relative measurement which
also can be used for the small resistance and the small capacitance measurements, for example, when performing resistance
measurement, connect the red testing line and the black testing line in short, press the REL△ key to record the values of
resistance (resistance of both the red and black lines), and after that performing resistance measurement again the lead
resistance will have been taken off from the displayed value. When performing capacitance measurement, open the red and
black testing line, press REL△ key to record the distributed capacitance, and after that performing capacitance measurement
again, the distributed capacitance will have been taken off from the displayed value. During relative measurement, analog bar is
always indicating the present measurement value but not the relative value. When measurement over, OL will display instead of
showing the relative value.
Notes: When going to relative value measurement under DC+AC mode, press RELΔ immediately after the digits refresh.
Maximum Value/Minimum Value/Maximum Value-Minimum Value Measurement
Except for frequency and diode measurements, by pressing the MAX/MIN key the meter will enter the maximum value and
minimum value record state and display the maximum value. The meter measures the present value and continuously judges if
it is necessary to update the maximum or minimum value. Pressing the MAX/MIN key again it is possible to select displaying
35
VA38 True RMS Multimeter
Operation Methods
the minimum value, the maximum value — minimum value or the maximum value. When the meter being in the maximum
and the minimum value record state, the analog bar is always indicating the present measurement value but not the MAX/MIN
value. Under the maximum and minimum value record state, press the MAX/MIN key for two seconds and then release it, the
meter will exit the MAX/MIN record state. When measurement over, OL will display instead of showing the MAX/MIN value.
Backlight Control
Pressing the LIGHT key, the LCD display screen’s backlight will be lighted and after 30 seconds it will automatically go out.
If press the LIGHT key again when the backlight is lighting, the backlight can be turned off in advance. Lighting the backlight
will cause three-times higher energy consumption than the ordinary operation. So by less use of backlight, power can be saved.
Data Hold
By pressing the HOLD key it is possible to hold the measurement value and the state at the moment of pressing the HOLD key.
While pressing the key again data measurement will be resumed.
Automatic Shutdown and Continuous Operation Mode Selection
After turning on power, the meter will in default enter the auto-shutdown timing state. Within 15 minutes after stopping to press
any key or turn the rotary switch, the meter will automatically turn off. After auto-shutdown, by pressing the WAKE key or
turning the rotary switch it is possible to wake the meter to resume operation. If you want the meter operates continuously
without shutdown, it will be done by pressing the WAKE at the same time when turning on power.
36
VA38 True RMS Multimeter
Operation Methods
Notes: After auto-shutdown there will still be a little electricity consumption in the meter, so it is recommended to turn off the
power when the meter is to remain un-working for a long time.
Connected to Computer RS-232C Interface
Pressing the HOLD key for two seconds and then releasing it, the meter will begin to send the measured data and state to
computer while the LCD display screen displaying
. Then it will be able to record、 analyze、 draw and print all
the measurement on computer as long as you insert one end of the RS-232C cable (options) into the front socket of the meter
and another end into the computer RS-232C interface and run the record and graphics software (options).And press the HOLD
key for two seconds and then release it again, the meter will stop to send data to computer, symbol
on the LCD
display screen will go out. When the meter sends data to computer it will cause the increase of the electricity consumption.
So
should be turned off when no need to transmit data.
37
VA38 True RMS Multimeter
Technological Specifications
Chapter 4
Technological Specifications
General Features
● Voltage between the measurement end and ground is of 1000V AC/DC. 1000V CAT Ⅲ, 2th pollution grade.
● 50000 counts, automatic/manual range, basic sampling rate 2.5 t/s and 51 segment analog bar.
● When rotary switch being in the positions of mV, logic frequency, diode, resistance and capacitance, the maximum
overload protection voltage will be 250V(effective value),while in the positions of μA/mA the protection current being
0.64A,and in the position of A, the protection current being 12.5A.
● Over range indication OL.
● When the total voltage of batteries being lower than 6.8V, the symbol for battery display will be lighted.
● Fuse being 0.63A/500V(μA/mA end) and 12.5A/500V (A end).
● Six 7# AA batteries X 1.5V.
● Infrared coupling RS-232C interface.
● Operating temperature: 0℃～30℃ (relative humidity 0～80%)
31℃～51℃ (relative humidity 0～50%)
● Storage temperature: -20℃～60℃ (relative humidity & lt; = 80%)
● Altitude:
operation less than 2000m,
storage
less than 10000m
● Volume：200mm X 100mm X 40mm
● Weight：560g
38
VA38 True RMS Multimeter
Technological Specifications
Range and Accuracy
The below-listed accuracies under different ranges refer to those which are guaranteed by the meter within one-year calibration,
with normal use under the operating temperature of 18℃-28℃ and relative humidity less than 80%.The presentation for
accuracy is: ± (**% reading digits + number of lower digits)
● AC Voltage/DC Voltage + AC Voltage
Range
Resolution
50mV
500mV
5V
50V
500V
1000V
0.001mV
0.01mV
0.1mV
1mV
10mV
0.1V
40Hz-1KHz
±(0.5% + 40)
±(0.5% + 40)
±(0.5% + 40)
±(0.5% + 40)
±(0.5% + 40)
±(0.5% + 40)
Accuracy
1KHz-10KHz
±(1% + 40)
±(1% + 40)
±(1% + 40)
±(1% + 40)
±(1% + 40)
unspecified
10KHz-20KHz
±(2.5% + 40)
±(2.5% + 40)
±(2.5% + 40)
±(2.5% + 40)
unspecified
unspecified
Notes: above accuracies can be guaranteed within 10%-100% of the full range.
● DC Voltage
Range
50mV
500mV
5V
50V
500V
1000V
Resolution
0.001mV
0.01mV
0.1mV
1mV
10mV
0 .1V
Accuracy
±(0.03%+10)
±(0.03%+6)
±(0.03%+6)
±(0.03%+6)
±(0.03%+6)
±(0.03%+6)
Notes: above accuracies can be guaranteed within the full range
39
VA38 True RMS Multimeter
Technological Specifications
● AC Current/DC Current + AC Current
Resolution
40Hz∽1KHz
Accuracy
1KHz∽10KHz
10KHz∽20KHz
500μA
0.01μA
±(0.75%+20)
±(1%+20)
±(2%+20)
5000μA
50mA
500mA
5A
10A
0.1μA
1μA
10μA
0.1mA
1mA
±(0.75%+10)
±(0.75%+20)
±(0.75%+10)
±(0.75%+20)
±(1.0%+10)
±(1%+10)
±(1%+20)
±(1%+10)
±(1.5%+20)
±(1.5%+10)
±(2%+10)
±(2%+20)
±(2%+10)
±(5%+20)
Unspecified
Range
Voltage Drop
102µV/µA
1.5mV/mA
30mV/A
Notes: above accuracies can be guaranteed within 10%-100% of the full range
● DC Current
Range
500μA
5000μA
50mA
500mA
5A
Resolution
0.01μA
0.1μA
1μA
10μA
0.1mA
Accuracy
±(0.15%+15)
±(0.15%+10)
±(0.15%+10)
±(0.15%+10)
±(0.5%+10)
10A
1mA
±(0.5%+10)
Notes: above accuracies can be guaranteed within the full range
40
Voltage Drop
102µV/µA
1.5mV/mA
30mV/A
VA38 True RMS Multimeter
Technological Specifications
● Resistance
Range
Resolution
500Ω
5KΩ
50KΩ
500KΩ
5MΩ
50MΩ
0.01Ω
0.1Ω
1Ω
10Ω
100Ω
1KΩ
Accuracy
±(0.1%+10)
±(0.1%+5)
±(0.1%+5)
±(0.1%+5)
±(0.1%+10)
±(0.5%+10)
Notes: above accuracies can be guaranteed within the full range
● Capacitance
Range
50nF
500nF
5μF
50μF
500μF
5000μF
Resolution
0.01nF
0.1nF
1nF
10nF
0.1μF
1μF
Accuracy
±(1%+5)
±(1%+5)
±(1%+5)
±(1%+5)
±(2%+5)
±(2%+5)
Notes: above accuracies for film capacitor or better can be guaranteed within the full range.
● Diode
Range
2.5V
Resolution
0.1mV
Accuracy
±(1%+5)
Notes: the test current is about 0.7mA
41
VA38 True RMS Multimeter
Technological Specifications
● Logic Frequency
Frequency Range
5Hz∽2MHz
Sensitivity
Vp 2∽5V square wave
● Linear Frequency
Frequency Range
Voltage/Current Range
Sensitivity
500mV
100mV
5V
0.5V
50V
4V
5Hz∽200KHz
500V
40V
(sine wave)
1000V
400V
1mA
5000μA
500mA
100mA
Notes: Low voltage or low frequency would lower the accuracy.
● Duty Ratio
Frequency Range
5Hz∽500KHz
42
Duty Ratio Range
5%∽95%
Resolution
0.01%
Accuracy
±(0.006%+4)
Accuracy
±(0.006%+4)
Accuracy
±(2%+5)
VA38 True RMS Multimeter
Maintenance
Chapter 5
Maintenance
Replacement of Batteries
If symbol
appears on the LCD screen during measurement, it indicates the total voltage of batteries being lower than
6.8V. For ensuring measurement accuracy, it is necessary to replace the batteries. Before the replacement, must take off the red
and black testing lines from the measured circuit and turn off the power of the meter. Loose the fixing screws of the cover by
a standard screwdriver, then remove the cover to take out all the old batteries, replacing them with the 7# batteries. Take care to
put in the batteries as the polarity specified on the shell of the meter. Put the cover as its origin. The meter must not be used
until the cover of batteries being put properly and locked in.
Replacement of Fuse
It must take off the red and black testing lines from the measured circuit and turn off the power of the meter before replacement
of fuse. It should only use fuse of the same model and the same electric specifications. Two fuses must not be put wrong in
positions during their replacement. And the meter must not be used until the cover of fuses being put properly and locked in.
Notes: generally, fuses will not be blown under the normal use of the meter. In case of blowing it is necessary first to find out
the reasons for the blowing and then take an account on the use of the meter. Generally, blowing may attribute to:
● Perform voltage measurement when the rotary switch being in the position of current.
● Current exceeds range.
43
VA38 True RMS Multimeter
Maintenance
Meter Calibration
There is no any component which can be used for calibration in the meter, calibration of the meter is implemented depending
on the built-in software in the meter. Professionals and accuracy-even-higher standard signal sources are required for
calibration of the meter. Users possessing such conditions may contact us for calibration methods when there is a need on
calibration meter, while those who having not such conditions can contact us for calibration matters.
Others
● In case of any default being found this meter must not be used continuously.
● When the meter needs repair, please send it to experienced professionals or the appointed maintenance department for
repairing.
● It should use soft cloth but not organic solvents which have corrosive and dissolving effect on the shell of meter to clean the
meter, and it should guard against water dropping into the meter.
44