Thank you for purchasing the True RMS 4000 Count Digital
Multimeter from AstroAI. This DMM is battery-powered,
equipped with a 4000-count display and automatic ranging.
This instrument performs AC/DC Voltage, AC/DC Current,
Resistance, Capacitance, Diode Testing, Continuity Testing,
NCV Detection, Live Wire Detection, and Battery Voltage
Testing. Thank you again for choosing AstroAI, if you have any
questions or concerns regarding your product, please contact
us at [email protected].
NOTE: Fully read and understand this manual before using
this Digital Multimeter. If you are a beginner to multimeters,
please read and keep this manual for reference.
WARNING
To avoid possible electric shock or personal injury, and to
avoid possible damage to the Meter or to the equipment being
tested, adhere to the following rules:
● Before using the Meter, inspect the exterior casing. Do not
use the Meter if it is damaged or if all or part of the exterior
casing is removed. Look for cracks or missing plastic. Pay
special attention to the insulation around the connectors.
● Do not use or store the Meter in a high-temperature
environment, do not expose to high levels of humidity, or
near strong magnetic fields. The performance of the Meter
may deteriorate after dampening.
● Inspect the test leads for damaged insulation or exposed
metal. Check the test leads for continuity.
● Pay special attention to the selections when measuring
current and voltage. If you attempt to measure in the wrong
setting, damage can occur to the Meter.
● Do not apply more than the rated voltage, as marked on the
Meter, between the terminals or between any terminal and
grounding.
● When the Meter is working at an effective voltage over 60V
in DC or 30V rms in AC, special care should be taken
because there is a danger of electric shock.
● Use the proper terminals, function, and range for your
measurements.
● When using the test leads, keep your fingers behind the
finger guards.
● Disconnect circuit power and discharge all high-voltage
capacitors before testing resistance, continuity, and diodes.
● Remove the connection between the testing leads and the
circuit being tested. Turn the Meter power off before opening
the Meter case.
● When servicing the Meter, use only the same model number
or identical electrical specifications replacement parts.
● The internal circuit of the Meter shall not be altered to avoid
damage of the Meter and any accident.
● Clean using a soft cloth and mild detergent for the surface of
the Meter. Do not use abrasive materials or solvents to
prevent the surface of the Meter from corrosion and
damage.
● Turn the Meter off when not in use and take out the battery
when it is not going to be used for an extended period of
time. Regularly check the battery as it may leak when it has
not been used for some time.
● Replace the battery as soon as leaking appears. A leaking
battery will damage the Meter.
● Do not move the multimeter while measuring to avoid
inaccurate readings.
ELECTRICAL SYMBOLS
INCLUDED IN BOX
● 1 x Owners Manual
● 1 x Pair of Test Leads
● 1 x AstroAI 4000 Counts Multimeter
DIMENSIONS
M4KOR
FUNC
HOLD
MAX
OFF
V
mV
A
mA
NCV
Live
10A
MAX MAX
COM
！
Ω
VΩLive
mA
1.5 V
9V
+-
12V
+-
600V CAT III
400mA/250V
！
MAX NCV
H
°F°CMKΩHz％n mVAFμ
Live
AC
DC
10A/250V
+-
Astro AI
59.1in
28.7in
MULTIMETER DIAGRAM
3
MAX Button
FUNC Button
1
Hold Button
2
Backlight Button
/ Flashlight Button
4
Rotary Switch
5
10A Terminal
6
COM Terminal
7
Input Terminal
8
NCV Detector
9
Flashlight
10
Indicator Light
11
LCD Screen
12
Test Leads
13
M4KOR
FUNC
HOLD
MAX
OFF
V
mV
A
mA
NCV
Live
10A
MAX MAX
COM
！
Ω
VΩLive
mA
1. 5V
9V
+-
12 V
+-
600V CAT III
400mA/250V
！
MAX NCV
H
°F°CMKΩHz％n mVAFμ
Live
AC
DC
10A/250V
+-
Astro AI
9
11
2
1
5
6
7
3
4
8
10
12
13
GETTING TO KNOW YOUR DEVICE
● BUTTONS FUNCTIONS
FUNC
Button Function
● Use the rotary switch to select a function. Use the
FUNC Button to further select the function if there
are multiple applications in one rotary setting.
● For example: Switching between AC and DC voltage
tests; Selecting between diode and continuity tests.
NOTE: Pay special attention to the selected setting
before performing any tests.
● SETTING FUNCTIONS
● LEAD TERMINALS
● OTHER FUNCTIONS AND FEATURES
Auto Shut Off:
● After 15 of standby, the Meter will automatically turn off. To
turn it on again, just rotate the range switch or press a
button.
● Remove Auto Off: When the multimeter is off, press and
hold the "FUNC” button, and then turn the rotary dial until
the meter beeps. The “APO” icon on the screen will
disappear, which means the auto shut off function is
cancelled. It will be restored again after restarting.
Replacing Batteries:
● If the low battery sign appears on the LCD display, the battery
should be replaced. Remove the rubber cover and the screws
on the back cover, replace the exhausted battery with fresh
batteries. (Size AAA, 1.5V x2).
● NOTE: Replace batteries immediately to prevent inaccurate
readings due to the low power. This also prevents potential
safety hazards.
Replacing Fuses:
Fuses rarely need to be replaced and are usually blown due to
operator error. To replace the fuses:
● Disconnect the test leads.
● Remove the rubber sleeve and the screws on the back
cover of the Meter.
● Open the back of the Meter and replace with fuses of the
same rating.
It is crucial that the replacement fuses have the same rating:
● Fuse 1: F400mA/250V fuse.
● Fuse 2: F10A/250V fuse.
HOW TO USE THIS MULTIMETER
This Digital Multimeter is very sensitive. It will be affected by
nearby magnetic fields. Without touching any objects, there
may be a reading jumping on the screen when it is turned on.
This is a normal occurrence of a digital multimeter and it does
not affect the measurement results.
VOLTAGE NOTES:
● To avoid damage to the meter, do not measure voltage
exceeding 600V DC or 600V AC.
● Pay special attention to the voltage setting of the Multimeter.
The LCD screen will indicate whether the setting is in AC.
Use the “FUNC” button to choose the correct setting.
● If the AC setting is used to measure DC and vice-versa,
there is potential to damage the Meter or any components
you are attempting to test.
RESISTANCE NOTES:
● Do not change the resistance while taking a measurement.
Doing so may damage the Meter and affect the test results.
● Do not test parallel circuits. The accuracy of the measurement
will be affected, and the results may not be accurate.
● Do not directly measure the internal resistance of micrometers,
galvanometers, batteries, and other instruments.
CONTINUITY NOTES:
● The audible “beep” sound indicates the resistance value of
the circuit under test is less than 30Ω.
● Overload Protection: 250V.
DIODE TEST TIPS:
Normal Diode Function:
● If the red test lead is connected to the positive pole of the
diode and the black lead is connected to negative, then the
diode should be in a forward conduction state, and the
displayed value is the forward voltage drop.
● Normal diode forward pressure drop: general silicon tubes
are 0.5-0.7V, germanium tubes are 0.15-0.3V.
● If "000 "is displayed, the diode is broken.
You can also verify that the red test lead is connected to the
negative pole of the tested diode and the black test lead is
connected to the positive pole if the reading displays “OL”.
POLARITY JUDGMENT METHOD:
● Switch the Multimeter to the Resistance setting.
● Connect the two test leads to the two electrodes of the
diode.
● Measure one result, then swap the positions of the test
leads, then measure the second result.
● The larger result is the reverse resistance and the smaller
result is the forward resistance. The smaller resistance is
when the black test lead is connected to the positive end of
the diode and the red lead is connected to the negative end.
How to tell if a common battery has power:
● Set the Multimeter to the appropriate Battery Test setting.
● If it is greater than or equal to the voltage marked on the
battery, it has normal power.
● If the measured voltage is lower than the voltage marked, it
means the battery is aging or needs to be changed.
VIII. NON-CONTACT VOLTAGE (NCV):
The NCV function detects AC voltage without the use of test
leads.
TROUBLESHOOTING
DC VOLTAGE
● Input Impedance: 10MΩ
● Overload Protection: 600V
● Max. Input voltage: 600V
AC VOLTAGE
Range
400mV
Resolution Accuracy
0.1mV
4V 0.001V
40V 0.01V
400V 0.1V
600V 1V
±(1.0 % of rdg+ 5dgts)
● Input Impedance: 10MΩ
● Overload Protection: 600V
● Max. Input voltage: 600V
● Frequency Range: 40Hz ~ 1KHZ
● Response: True RMS
DC CURRENT
● Overload Protection:
mA:F400mA/250V fuse
A:F10A/250V fuse
(For measurements >5A: duration <10 seconds, interval >15
minutes)
AC CURRENT
Range
40mA
Resolution Accuracy
0.01mA
400mA 0.1mA
10A 0.01A
±(1.5% of rdg+ 5dgts)
● Overload Protection:
mA:F400mA/250V fuse
A:F10A/250V fuse
(For measurements>5A: duration <10 seconds, interval >15
minutes)
● Frequency Range: 40Hz ~ 1KHZ
● Response: True RMS
RESISTANCE
● Overload Protection: 250V
CAPACITANCE
Range
4nF
Resolution Accuracy
0.001nF
40nF 0.01nF
400nF 0.1nF
4μF 0.001μF
40μF 0.01μF
±(4.0% of rdg + 5dgts)
400μF 0.1μF
4mF 0.001mF
● Overload Protection: 250V
Web:.astroai.com
E-mail:[email protected]
3 YEAR WARRANTY LIMITED WARRANTY FROM ASTROAI
Each AstroAI Digital Multimeter will be free from defects in
material and workmanship. This warranty does not cover
fuses, disposable batteries and damage from neglect, misuse,
contamination, alteration, accident, or abnormal conditions of
operation or handling, including overvoltage failures caused by
use outside the Multimeter’s specified rating, or normal wear
and tear of mechanical components. This warranty covers the
original purchaser only and is not transferable. If this product
is defective, please contact AstroAI Customer Support at
BATTERY TEST
Range
1.5V
Resolution Load Resistance
0.001V
9V 0.01V
12V 0.01V
30Ω
300Ω
300Ω
True RMS 4000 Count
Digital Multimeter
V1.0
M4KOR
FUNC
HOLD
MAX
OFF
V
mV
A
mA
NCV
Live
10A
MAX
MAX
COM
！
Ω
VΩLive
mA
1.5V
9V
+-
12V
+-
600V CAT III
400mA/250V
！
MAX NCV
H
°F°CMKΩHz％n mVAFμ
Live
AC
DC
10A/250V
+-
AstroAI
Compliant with
EU Standards
Warning
Earth Ground
DC(Direct Current)
Fuse
AC and DC
Double Insulation
Low Battery Symbol
Category III test equipment is suitable for testing
and measurements of circuits connected to the
power distribution portion of a low-voltage power
supply unit in a building.
CATⅢ
！
AC
(Alternating Current)
Setting
Function
AC/DC Voltage Test:0.01V~600V
AC/DC Voltage Test:0.1mV~400mV
Resistance Test:0.1Ω~40MΩ
NOTE: Use the FUNC Button to further select the function
if there are multiple functions in one rotary setting.
V
mV
Ω
Capacitance Test:0.01NF~4MF
Audible Continuity Test
Diode Test
Battery Voltage Test:1.5V, 9V, 12V
AC/DC Current Test:400mA~10A
AC/DC Current Test:0.01mA~400mA
A
mA
+-
、
NCV Detection
Live Wire Detection
NCV
Live
1
3
2
1
Plug the red test lead into this terminal for
currents between 400mA and 10A.
2
Plug in the red test lead for all measurements
except when current is greater than or equal
to 400mA.
3
Plug the black test lead into this terminal.
BATTERY TEST TIPS:
How to tell if a car battery is aging:
● Set the Multimeter to the appropriate Battery Test setting.
● Connect the test leads to the positive and negative terminals
of the battery.
● Start the car and turn on the air conditioner in the car. Check
the voltage indication.
● If the voltage drops severely, the battery is aging. If the
battery voltage is significantly lower than 12V during this
test, it means the car battery needs to be replaced.
Range
40mA
Resolution Accuracy
0.01mA
400mA 0.1mA
10A 0.01A
±(1.2% of rdg+ 5dgts)
Range
400Ω
Resolution Accuracy
0.1Ω
4kΩ 0.001kΩ
40kΩ 0.01kΩ
400kΩ 0.1kΩ
4MΩ 0.001MΩ
40MΩ 0.01MΩ
±(1.0% of rdg + 5dgts)
HOLD
MAX
● Press this button to display and hold the maximum
value the multimeter records during a
measurement test. The maximum values will be
cleared when the test function changes or the
meter is turned off.
● Backlight: Press this button to turn on/off the
screen’s backlight.
● Flashlight: Press this button to turn on/off the
flashlight.
● Press this button while performing a test to hold
(freeze) the reading for easy recording.The screen
will display“ ”when the hold function is
activated.Press the button again to cancel the data
hold.
H
-2- -3- -4- -5- -6-
-7-
-8- -9- -11- -12- -13- -14- -15- -16- -17- -18- -19- -20- -21- -22- -23-
The reading does
not stabilize
● Check the test leads for damage.
● Check the contact between test
leads and object being measured.
● Check the connection between the
test leads and the Meter.
Reading is not
accurate
● Check the test leads for damage.
● Check if the battery needs to be
replaced.
A certain range is
not available
● Adjust the setting of the Rotary Dial
to the required setting.
Range error is
large
● The variable value of shunt
resistance needs to be adjusted or
replaced.
No reading
● Check whether the fuse is intact.
● Check the test leads for damage.
4V 0.001V
40V 0.01V
400V 0.1V
600V 1V
±(0.5% of rdg + 5dgts)
Range
400mV
Resolution Accuracy
0.1mV
CURRENT NOTES:
● If you insert the red test lead into the 10A jack, be sure to
insert the test lead back into the "Input" jack after the test to
avoid forgetting to switch the jack for the next operation and
burn the Multimeter.
● When testing a high current, for safety reasons, each
measurement should not exceed 10 seconds, and the
interval time between tests should be greater than 15
minutes.
尺寸：100*140mm
Ⅰ. MEASURING VOLTAGE:
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the
“COM” (black) terminal.
● Turn the rotary dial to the“ ”setting. When
the voltage is below 400mV, turn the dial to
the“ ”setting. Press the “FUNC” button
to switch between AC/DC. The screen will
indicate “DC” when in the DC setting and
“AC” when in the AC setting.
V
mV
V
AC
V
DC
-10-
● Connect the two test leads to the neutral and live wires
respectively (red to live, black to neutral).
● After the reading stabilizes, record the reading from the LCD
screen.
● Turn the rotary switch to the OFF position to turn off the
Meter.
Ⅱ. MEASURING RESISTANCE:
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the
“COM” (black) terminal.
● Turn the rotary dial to the“ ”setting.
Ω
● Place the test leads at both ends of the resistance to be
measured and maintain a strong contact.
● The results will be displayed on the LCD screen.
● If the measured value is equal to the nominal resistance of
the resistor or within the range of error, the resistor is
functioning correctly.
If there is a large deviation between the nominal resistance
and the measured resistance, the resistor is bad.
If the measured resistance is infinite (open circuit), zero
(short circuit), or unstable, it means the resistor is damaged
and can no longer be used.
III. MEASURING CAPACITANCE:
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the
“COM” (black) terminal.
Ω● Turn the rotary dial to the“ ”setting. Press the
“FUNC” button to switch to Capacitance Test.
● Create a strong connection between the test leads and both
ends of the capacitor.
● Measurement results will be displayed on the LCD screen.
Ⅳ. CONTINUITY TEST:
● Deenergize the circuit you will be testing.
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the “COM”
(black) terminal.
● Turn on the Multimeter by setting it to“ ”.
Touch the test lead tips together to check if
they are connected normally. An audible
sound should occur.
● Place the test leads on both sides of the object
to be measured.
If the line is connected, the buzzer will beep,
and the indicator light will turn green. The
screen will also display a resistance reading.
If there is no continuity, the buzzer will not sound, and “OL” will
be displayed on the screen, indicating infinite resistance.
Ω
V. DIODE TEST:
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the “COM”
(black) terminal.
● Turn the rotary dial to the“ ”setting. Press the
“FUNC” button to switch to Diode Test.
● Connect the red test lead to the positive end of the diode
and the black test lead to the negative end.
NOTE: Generally, the positive end of the diode is the longer
end.
V
● The LCD will display the reading of the voltage
decreased by the diode. If the leads are
connected incorrectly to the diode’s electrodes,
the LCD will display “OL”.
VI. BATTERY TEST:
● Insert the red test lead into the “Input” (red)
terminal and the black test lead into the
“COM” (black) terminal.
● Use the Rotary Dial to select the Battery Test Setting of the
battery for testing 1.5, 9, and 12V“ ”batteries.
● After the reading is stable, get the reading from the LCD
screen.If the battery voltage is low, the indicator light will turn
red.
● Connect the red test lead to the positive electrode and the
black test lead to the negative electrode.
Ⅶ. MEASURING CURRENT:
● Turn the rotary dial to the“ ”or“ ”setting,
according to the current level.
● Press the “FUNC” button to switch between
AC/DC. When the screen displays “DC” the
Meter is in the DC function, when “AC” is
displayed, the Meter is in the AC function.
m A
DC
m A
AC
● Under the“ ”setting, connect the red test
lead to the 10A (red) terminal and the black
test lead to the COM (black) terminal.
● Under the“ ”setting, connect the red test
lead to the“ ”(red input) terminal and the
black test lead to the COM (black) terminal.
VΩLive
mA
● Disconnect the power supply of the circuit under test.
Connect the Meter to the circuit under test in series, and
then turn on the power supply of the circuit.
● The reading will be displayed on the LCD screen.
AUTOMOTIVE PARASITIC BATTERY DRAIN:
● Check if the battery voltage and power generation are
within normal range. The battery voltage is generally
around 12.7V and the power generation is around 14V.
● Turn off all electrical accessories inside and outside the car
and close the doors.
● Remove the negative electrode of the battery. Set the
Multimeter to the maximum current level and connect the
Meter in series to the battery. Connect the red test lead to
the negative line and the black test lead to the battery
terminal.
● Adjust the Meter, if necessary, to a lower range.
● Wait for about 30 minutes; after all the modules of the
vehicle enter the sleep state, read the accurate static
discharge current. The discharge current is generally 0.02A
(20mA), however, this can vary depending on the vehicle.
Generally, it is normal to not exceed 50mA.
● If the drain is larger than 50mA, begin checking fuses
individually for which circuit is carrying the excess load.
If a removed fuse reduces the battery draw to below 50mA,
it can be determined the corresponding circuit is drawing
the excess discharge.
● Set the Rotary Dial to the NCV function“ ”.
● Move the NCV detector close to the point to be tested.
● When the Meter senses a weak AC signal, the green
indicator light will turn on and the buzzer will emit a slow,
audible beep.
● When the Meter senses a strong AC signal, the red
indicator light will turn on and the buzzer will emit a quick
beep.
NCV NOTE: This function does not affect the Meter’s
measurement after exiting the NCV setting. If the range
switch is not in the NCV position, the Meter will operate
normally.
Ⅸ. LIVE WIRE DETECTION:
● Insert the red test lead into the “Input” (red)
terminal. Do not insert the black test lead
into any terminal.
● Turn the Rotary Dial to the“ ”setting. Press the
“FUNC” button to switch to Live Wire Detection
and the screen will show “Live”.
● Touch the point to be measured with the tip of the red test
lead.
● When the Meter senses a weak AC signal, the green
indicator light will turn on, and the buzzer will emit a slow,
audible beep.
● When the Meter senses a strong AC signal, the red indicator
light will turn on, and the buzzer will emit a quick beep.
● When testing the current, there must be a load in the circuit.
Do not connect the multimeter in series with the circuit
without a load to measure; doing so can potentially damage
the Meter.
● Do not apply a current exceeding the Meter’s range to avoid
damaging the Meter.
● If the measured value is 0, it means the battery has a large
internal resistance or the battery is broken.
NOTE: Do not directly test the battery with the Current or
Resistance Settings.
