AstroAI CM4K0R Digital Clamp Meter User Manual

Introduction

Thank you for purchasing the AstroAI Auto Ranging 4000 Counts Digital Clamp Meter. This clamp meter is designed for safe and accurate use by professionals and DIYers. This manual provides all safety information, operation instructions, specifications, and maintenance information for the meter. The instrument measures AC/DC Voltage, AC/DC Current, Resistance, Audible Continuity, Diode, Frequency, Capacitance, NCV (Non-Contact Voltage), Live Wire test, and Duty Cycle testing. For any questions, please contact support@astroai.com.

! Fully read and understand this manual before using this digital clamp meter.

Warning

To avoid electric shocks, personal injury, and damage to the clamp meter/equipment being tested, adhere to the following rules:

• Use the meter strictly in accordance with this manual; failure to do so may weaken or damage the meter's internal protections.
• Be especially careful when measuring over 60 V DC, 30 V AC RMS, or 42 V peak value, as there is an increased danger of electric shock.
• Do not apply more than the rated voltage, as marked on the meter, between terminals or between any terminal and grounding.
• Check meter operation by measuring a known voltage; do not use if readings are incorrect or the meter is damaged.
• Before use, check for damage to the plastic parts of the casing. Do not use if any part of the exterior casing is damaged.
• Before use, check test leads for cracks or damage. If damaged, replace them immediately with leads of the same model and electrical specifications.
• Only use this meter within the measurement ranges listed in this manual and on the meter.
• Replace the battery as soon as the low-battery indicator appears to avoid measurement errors.
• Do not use the meter around explosive gas, steam, or in humid environments.
• Comply with local and national safety regulations. Wear personal protective equipment (e.g., approved rubber gloves, masks, flame-resistant clothing) to prevent injury from electric shocks and arcs when hazardous live conductors are exposed.
• When using test leads, keep fingers behind the finger guards.
• Do not measure current when the test lead is inserted into the INPUT Terminal.
• Do not let the meter operate alone; ensure supervision when in use.
• When measuring, connect the neutral or ground wire first, then the live wire. When disconnecting, disconnect the live wire first, then the neutral wire, and finally the ground wire.
• Before opening the case or battery cover, remove test leads. Do not use the meter when it is disassembled or the battery cover is open.
• To ensure safety, use only the equipped test leads. Replace damaged test leads with the same model and electrical specifications.

Package Includes

• User Manual × 1
• Pair of Test Leads × 1
• Storage Bag × 1
• AstroAI 4000 Counts Clamp Meter × 1

Electrical Symbols

• ~ AC (Alternating Current)
• -- DC (Direct Current)
• ~-- AC and DC
• 카 Capacitance Test
• Ω Resistance Test
• Π Double Insulation
• NCV Non-Contact Voltage Setting
• mV/V Voltage
• Live Live Wire Detection
• Low Battery Symbol
• ))) Audible Continuity Test
• →|- Diode Test
• = Earth Ground
• Hz Frequency
• ! Warning
• % Duty Cycle
• mA/A Current
• CE Compliant with EU Standards

Dimensions and Diagram

Dimensions: 7.68 in / 19.5 cm (length), 2.68 in / 6.8 cm (jaw opening), 1.14 in / 2.9 cm (width).

Diagram:

• [1] Storage Bag: A bag with the AstroAI logo.
• [2] Test Leads: A pair of test leads with probes.

Meter Diagram Description:

The clamp meter features a clamp jaw [4] with an NCV detector [3] at the tip. A trigger [7] is located below the jaws. The front panel includes a flashlight [5], a rotary switch [8] for selecting measurement functions (OFF, Hz, 400A, LPF/40A, Ω, ))), →|-, Hz/%, NCV/Live), a FUNC button [10], a ZERO button [11], and a MAX/MIN button [12]. The LCD screen [13] displays readings. The bottom has a COM terminal [14] and an INPUT terminal [23]. An indicator light [21] and a flashlight/backlight button [22] are also present.

Button Functions

FUNC Button [10]

Use the FUNC Button to further select the function if there are multiple functions in one rotary setting. Note: Pay special attention to ensure the selected setting is correct before performing any test.

HOLD Button [24]

Press the HOLD Button to hold or cancel the data. Press this button while performing a test to hold (freeze) the reading for recording. While the hold function is active, the screen will keep the reading displayed. Press the HOLD Button again to turn off this function. Note: The screen will display "H" when the data hold function is activated.

MAX/MIN Button [12]

Press the MAX/MIN Button to toggle the maximum value record. Use this function to record the maximum/minimum value in the measurement scale. First, connect the meter to the circuit, then press the MAX/MIN Button (do not remove test leads during this measurement) to turn on the maximum/minimum value function. The LCD display will show the maximum/minimum value of all the measured data. Press and hold the button for more than two seconds to exit this function. Note: The screen will display "MAX" when the maximum value function is turned on. The screen will display "MIN" when the minimum value function is turned on.

Flashlight/Backlight Button [22]

Press and hold the [Flashlight/Backlight Button] to turn on the flashlight. Press the [Flashlight/Backlight Button] to turn on the backlight; this makes it easier to read the screen in dim light. Press the [Flashlight/Backlight Button] again to turn off the backlight. Press and hold the [Flashlight/Backlight Button] again to turn off the flashlight.

ZERO Button [11]

Press the ZERO Button to reset the reading in DC mode.

Preparation

1. Insert the red test lead into the INPUT terminal [23] and the black test lead into the COM terminal [14].
2. Turn the rotary dial to the continuity test ))) and touch the red and black test leads together to check whether they are functioning normally. The buzzer will beep and the indicator light [21] will illuminate if the test leads are normal.

Operation Instructions

I. Measuring AC/DC Current

1. Turn the rotary dial to the "400A" or "40A" setting. The screen will display "DC" for DC current.

Note: In DC mode, press the "ZERO" Button to reset the reading on the screen before measuring; "ZERO" will be displayed.

2. Press the FUNC Button [10] to switch to AC current mode. The screen will display "AC".

3. Press the trigger [7] to open the transformer jaws [4]. Clamp the conductor to be tested and slowly release the trigger until the clamp head is completely closed. Ensure the conductor to be tested is in the center of the clamp head. Measurement errors will occur if the conductor is not placed in the center of the clamp head.

4. After the reading stabilizes, record the reading from the LCD screen [13].

5. Turn the rotary switch [8] to the OFF position to turn off the meter.

Note: When measuring AC current, press the FUNC Button [10] to check the frequency and enter the low-pass filtering (LPF) mode. The screen will display "Hz" and "LPF" respectively.

II. Measuring AC/DC Voltage

1. Turn the rotary dial to the "V" setting. The screen will display "DC" indicating that the meter is measuring DC voltage.

2. Press the FUNC Button [10] to switch to the AC voltage test. The screen will display "AC" indicating that the meter is measuring AC voltage.

Note: When measuring AC voltage, press the FUNC Button [10] to view the frequency and enter the low-pass filtering (LPF) function. The screen will display "Hz" and "LPF", respectively.

3. Connect the meter in parallel to the circuit under test.

Note: If the reading is negative when measuring the DC voltage, it means that the positive and negative poles of the test leads are reversed; please put the test leads in the appropriate position.

4. After the reading stabilizes, record the reading from the LCD screen [13].

5. Turn the rotary switch [8] to the OFF position to turn off the meter.

Voltage Notes:

• To avoid damaging the meter, do not measure voltage exceeding 600 V DC or 600 V AC CAT III.
• Pay special attention to which voltage mode the clamp meter is in. The LCD screen will indicate whether the setting is in AC. Use the "FUNC" Button [10] to choose the correct setting.
• If the AC setting is used to measure DC and vice versa, an overflow symbol "OL" will be displayed. Performing this has the potential to damage the meter and any components you are attempting to test.
• When measuring voltage, the result will fluctuate depending on the power supply. Generally speaking, the result will fluctuate ±10 V, which is NOT an inaccurate result.

III. Measuring Resistance

1. Turn the rotary dial to the "Ω" setting. The screen will display "Ω" indicating that the meter is measuring resistance.

2. Connect the test leads to both ends of the circuit or resistor under test in parallel.

3. After the reading stabilizes, record the reading from the LCD screen [13].

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

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.

IV. Measuring Capacitance

1. Turn the rotary dial to the "f" setting. Press the FUNC Button [10] to switch to the capacitance test. The screen will display "nF" indicating that the meter is testing capacitance.

2. Connect the test leads to both ends of the circuit or resistor under test in parallel.

3. After the reading stabilizes, record the reading from the LCD screen [13].

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

Capacitance Tips:

• If the measured value is significantly different from the value marked on the capacitor, the capacitor is damaged.

Capacitance Notes:

• Before measuring the capacitance, discharge the capacitor to avoid damaging the meter. Do so by connecting the capacitor to a high-powered resistor.
• Discharge the capacitor after measurement to avoid any potential safety hazards.
• If the capacitance is large, it may take a long time for the reading to stabilize.

V. Continuity Test

1. Insert the red test lead into the INPUT terminal [23] and the black test lead into the COM terminal [14].

2. Turn the rotary dial to the ")))" setting. The screen will display ")))" indicating that the meter is testing continuity. Touch the red and black test leads together to check whether they are functioning normally. The buzzer will beep and the indicator light [21] will illuminate if the test leads are normal.

3. Connect the test leads to both ends of the circuit or resistor under test in parallel. If the resistance of the circuit or resistor under test is connected and less than 50 Ω, the buzzer will emit a beep and the measured resistance value will be displayed on the LCD display.

4. If the circuit or resistor under test is disconnected, or the resistance value is greater than 50 Ω, the LCD screen will display "OL".

5. Turn the rotary switch [8] to the OFF position to turn off the meter.

VI. Diode Test

1. Turn the rotary dial to the "→|-" setting. Press the FUNC Button [10] to switch to the diode test. The screen will display "V" indicating that the meter is testing the diode.

2. Connect the red test lead to the anode of the diode under test and the black test lead to the cathode of the diode. Note: Usually the anode of the diode is the longer end.

3. The LCD screen [13] will display the approximate voltage drop reading of the diode. If the test leads are connected reversely, "OL" will be displayed on the LCD screen. Please reposition the test leads to the correct position to measure again.

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

Diode Test Tips:

• Is the diode functioning correctly? If the red test lead is connected to the positive pole of the diode and the black lead is connected to the negative, then the diode should be in a forward conduction state. If so, the displayed value is the forward voltage drop.
• Normal diode forward pressure drops: the general silicon tube is 0.5-0.7 V, a germanium tube is 0.15-0.3 V.
• If "0000" 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. The meter should display "OL".

Polarity Judgment Method:

1. Switch the clamp meter to the Resistance setting.
2. Connect the two test leads to the two electrodes of the diode.
3. Measure one result, then swap the positions of the test leads. Then, measure the second result.
4. 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.

VII. Frequency Test

1. Turn the rotary dial to the "Hz/%" setting. The screen will display "Hz" indicating that the meter is testing frequency.

2. Connect the test leads in parallel to both ends of the power supply or circuit to be tested.

3. After the reading stabilizes, record the reading from the LCD screen [13].

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

VIII. Duty Cycle Test

1. Turn the rotary dial to the "Hz/%" setting. Press the FUNC Button [10] to switch to the duty cycle test. The screen will display "%" indicating that the meter is testing the duty cycle.

2. Connect the test leads in parallel to both ends of the power supply or circuit to be tested.

3. After the reading stabilizes, record the reading from the LCD screen [13].

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

IX. Non-Contact Voltage (NCV)

1. Turn the rotary dial to the "NCV/Live" setting. The screen will display "NCV" indicating that the meter is testing non-contact voltage.

2. Move the NCV detector [3] close to the point to be tested:

• When the meter senses a weak AC signal, the green indicator light [21] will illuminate, the buzzer will emit a slow, audible beep and the screen will display "---L".
• When the meter senses a strong AC signal, the red indicator light [21] will illuminate, the buzzer will emit a rapid beep and the screen will display "---H".

Note: When the indicator light [21] is on, it means there is voltage, please pay attention to your safety!

3. Turn the rotary switch [8] to the OFF position to turn off the meter.

X. Live Wire Detection

1. Insert the red test lead into the INPUT terminal [23].

2. Turn the rotary dial to the "NCV/Live" setting. Press the FUNC Button [10] to switch to live wire detection. The screen will show "Live" indicating that the meter is testing live wire detection.

3. Touch the point to be measured with the tip of the red test lead:

• When the indicator light [21] is on, it means that the measured position is a live wire, please pay attention to your safety! The reason that the green light is on may be that the test lead is not fully connected to the socket. Please test again after the test lead is fully connected.

Note: When the meter senses a weak AC signal, the LCD screen will display "---L" and the buzzer will emit a slow beep. When the meter senses a strong AC signal, the LCD screen will display "---H" and the buzzer will emit a rapid beep.

4. Turn the rotary switch [8] to the OFF position to turn off the meter.

Auto Power Off:

Rotating the rotary switch [8] from the OFF position to any gear will turn on the meter. After 15 minutes of standby, the meter will automatically power off. To turn it on again, just rotate the range switch or press a button.

Maintenance

Cleaning the Meter

If there is dust or humidity in the terminals, it may produce erroneous measurements. Please clean the meter as described:

1. Turn off the power to the meter and remove the test leads.
2. Turn the meter over and shake out the accumulated dust in the input terminal. Then, wipe the case with a damp cloth or mild detergent. Wipe the contacts in each terminal with a clean cotton swab dampened in alcohol.

Replacing the Battery

1. Turn off the meter and remove the test leads.
2. Unscrew the screws securing the battery cover with a screwdriver and remove the battery cover.
3. Remove the old battery and replace it with a new battery of the same specification.
4. Put the battery cover back in its original position and secure the battery cover with the removed screws.

Battery Type: 2 x 1.5 V AAA Batteries.

Specifications

Detailed Specifications

Operating Temperature Range: 18 °C to 28 °C

Relative Humidity: ≤ 80%

Accuracy: ± (%rdg + dgts)

The accuracy is applicable within one year after calibration.

I. DC Voltage

• Input Impedance: 10 MΩ
• Overload Protection: 600 V
• Maximum Measuring Voltage: 600 V

II. AC Voltage

• Input Impedance: 10 MΩ
• Overload Protection: 600 V
• Maximum Measuring Voltage: 600 V
• Frequency Range: 40 Hz ~ 1 kHz
• Response: True RMS

III. DC Current

IV. AC Current

• Frequency Range: 40 Hz ~ 400 Hz
• Response: True RMS

V. Resistance

Overload Protection: 250 V;

VI. Capacitance

Overload Protection: 250 V;

VII. Frequency/Duty Cycle

Frequency measurement by "Hz" setting:

• Measuring Range: 0 ~ 4 MHz
• Voltage Range: 0.2~10 V AC
• Overload Protection: 250 V;

Frequency measurement by "V" setting:

• Measuring Range: 0 ~ 100 kHz
• Voltage Range: 0.5~600 V AC
• Overload Protection: 250 V;

Frequency measurement by "A" setting:

• Measuring Range: 0 ~ 1 kHz
• Signal Range: ≥1/4 range

VIII. Continuity Test

• The buzzer inside the meter will beep if the resistance <50 Ω.
• Open Circuit Voltage: Approximately 1.0 V
• Overload Protection: 250 V

IX. Diode Test

• The approximate diode forward voltage value will be displayed.
• Reverse DC Voltage: Approximately 2.0 V
• Overload Protection: 250 V

Recycling

Dispose of the product responsibly at the end of its service life by recycling parts according to local guidelines.

Warranty Period

3-Year Limited Warranty from AstroAI

Each AstroAI Digital Clamp Meter is warranted against defects in material and workmanship. This warranty excludes fuses, disposable batteries, and damage from neglect, misuse, contamination, alteration, accident, abnormal operation, over-voltage, or normal wear and tear. The warranty covers the original purchaser only and is non-transferable. For defective products, contact AstroAI Customer Support at support@astroai.com.