AstroAI DM130B Digital Multimeter User Manual

Introduction

Thank you for purchasing the AstroAI True RMS 4000 Count Digital Multimeter. This multimeter is designed for professionals and DIY enthusiasts seeking enhanced functionality and accuracy. This manual provides comprehensive safety information, operating procedures, specifications, and maintenance tips.

The device can be used for AC/DC Voltage, AC/DC Current, Resistance, Continuity, Diode, Capacitance, NCV, and Battery Voltage testing.

For any questions or concerns, please contact support@astroai.com.

Safety Precautions (Warnings)

To prevent electric shock, injury, meter failure, or damage to the tested equipment, always adhere to the following:

• Inspect the meter's exterior for damage before use. Do not use if damaged or if parts are detached. Check for cracks or chips, especially around connectors.
• Inspect test leads for insulation damage or exposed metal. Verify test lead continuity.
• Exercise caution when selecting settings for current and voltage measurements. Incorrect settings can damage the multimeter.
• Do not connect the meter to measure voltages exceeding its rated limits between terminals or between terminals and ground.
• Ensure the dial is set to the correct position before measuring. Do not change the dial position during measurement.
• Be aware of potential electric shock when measuring voltages exceeding 60V DC or 30V AC (RMS).
• Always use the appropriate terminals, functions, and ranges for your measurements.
• Avoid using or storing the meter in high temperatures, strong magnetic fields, or humid environments, as this can degrade performance.
• Ensure fingers do not extend beyond the finger guards on the test leads.
• Before testing resistance, continuity, diode, or hFE, disconnect power and discharge high-voltage capacitors.
• Replace batteries promptly when the battery indicator appears. Low battery levels can lead to inaccurate readings and potential hazards.
• Turn off the meter and disconnect test leads before opening the case.
• Use only replacement parts with the same model number or electrical specifications for maintenance.
• Do not modify the internal circuitry of the meter, as this can cause malfunction and injury.
• Clean the meter surface with a soft cloth and mild detergent. Avoid abrasive cleaners or chemicals.
• Turn off the meter when not in use. If storing for extended periods, remove batteries to prevent leakage, which can damage the meter.

Included Items

• Instruction Manual (x1)
• Test Leads (x1)
• Alligator Clips (x1)
• AstroAI 4000 Count Digital Multimeter (x1)

Diagram and Components

The multimeter features a clear layout with the following components:

• ① LCD Screen: Displays measurement readings and status indicators.
• ② Select Button: Used to select specific functions or modes after setting the dial.
• ③ Battery Voltage Setting: Dial position for battery voltage testing.
• ④ Capacitance Setting: Dial position for capacitance measurement.
• ⑤ Resistance/Diode/Continuity Setting: Dial position for these measurements.
• ⑥ AC/DC Voltage Setting: Dial position for voltage measurements.
• ⑦ OFF Mode: Dial position to turn the multimeter off.
• ⑧ Dial: The main selector dial to choose measurement function and range.
• ⑨ "10A" Input Jack: For measuring current up to 10A.
• ⑩ Hold/Backlight Button: Freezes the displayed reading (Hold function) or turns the LCD backlight on/off.
• ⑪ AC/DC Current Setting: Dial position for current measurements (µA, mA, A).
• ⑫ NCV Setting: Dial position for Non-Contact Voltage detection.
• ⑬ "COM" Input Jack: Common terminal for test leads.
• ⑭ "INPUT" Input Jack: Standard input for test leads (used for most measurements except 10A current).
• ⑮ Alligator Clips: Accessories for connecting test leads to test points.
• ⑯ Test Leads: Probes for connecting to the circuit under test.

Dimensions

The multimeter has the following approximate dimensions:

• Width: 5.71 inches (145 mm)
• Height: 2.87 inches (73 mm)
• Depth: 1.34 inches (34 mm)

Electrical Symbols

The following symbols may appear on the multimeter or in its documentation:

• AC (交流): Alternating Current (~).
• DC (直流): Direct Current (=).
• AC and DC (ACとDC): Both AC and DC (~=).
• Battery Test (バッテリーテスト): Battery voltage testing mode.
• Negative Value (マイナス測定値): Indicates a negative reading (-).
• Continuity Test (導通テスト): Indicates continuity (low resistance) with a buzzer sound (?).
• Diode Test (ダイオードテスト): Diode testing mode, shows forward voltage drop (⚡).
• Resistance (Ω抵抗): Resistance measurement (Ω).
• CE: Conforms to EU directives.
• Automatic Power Off (自動電源オフ): Feature to conserve battery.
• Data Hold (データホールド): Freezes the current reading (H).
• Capacitance (キャパシタンス): Capacitance measurement (?️).
• Warning (警告): Indicates a potential hazard (⚠️).
• Low Battery (低バッテリー): Battery needs replacement (?).
• High Voltage (危険な高電圧を伴う): Indicates measurement involves high voltage.
• Ground (接地アース): Earth ground connection (⏚).
• Double Insulation (2重絶縁): Indicates a double-insulated device for safety (□).

Function Buttons

Select Button

Used to select specific functions or modes after the main function is set with the dial.

Hold/Backlight Button

Press to freeze the displayed reading (Hold function). Press again to release. Pressing this button also turns the LCD backlight on or off.

Preparation

1. Connect Test Leads: Insert the black test lead into the "COM" jack and the red test lead into the "INPUT" jack.
2. Test Lead Continuity: Touch the tips of the red and black test leads together. A continuous, loud buzzer sound indicates the leads are functioning correctly.

Operating Procedures

This digital multimeter is sensitive and may be affected by nearby magnetic fields. When powered on, readings might appear on the screen even without touching anything. This is normal and does not affect measurements.

Voltage Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the desired voltage setting (V= for DC, V~ for AC). Use the "Select" button to switch between DC and AC if applicable.
3. Connect to Circuit: Connect the test leads in parallel across the component or points where voltage needs to be measured.
4. Record Result: Note the reading on the LCD screen.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Voltage Measurement:

• When selecting a low range, unstable readings may occur if test leads are not connected to a load. This is normal.
• For DC voltage, the presence or absence of a "■" symbol on the screen can help identify the polarity of the red test lead. No "■" indicates the red lead is connected to the positive terminal.
• Do not measure voltages exceeding 600V DC or 600V AC, as this can damage the meter.
• Do not use AC voltage test functions for DC voltage, or vice versa, as this may damage the meter or the device under test.

Current Measurement

1. Connect Test Leads: Black lead to "COM". For currents below 500mA, insert the red lead into the "INPUT" jack. For currents between 500mA and 10A, insert the red lead into the "10A" jack.
2. Select Function: Turn the dial to the appropriate current range (µA, mA, A). Use the "Select" button to choose between DC and AC current.
3. Connect to Circuit: Connect the test leads in series with the circuit or component where current needs to be measured.
4. Record Result: Note the reading on the LCD screen.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Current Measurement:

• Do not measure currents exceeding 10A AC/DC, as this can damage the meter.
• For DC current, the "■" symbol on the screen indicates polarity. No "■" means the red lead is connected to the positive terminal.
• For safety, limit high current measurements to under 10 seconds. Allow at least 15 minutes between tests.
• Ensure the circuit has a load when testing current. Do not connect the multimeter in series to an unloaded circuit, as this may cause damage.

Battery Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the appropriate battery voltage setting (1.5V, 9V, 12V).
3. Connect to Battery: Connect the test leads to the positive and negative terminals of the battery.
4. Record Result: Note the reading on the LCD screen.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Battery Measurement:

• The "■" symbol on the screen indicates polarity for battery measurements. No "■" means the red lead is connected to the positive terminal.
• When testing batteries of unknown voltage, start with the 12V range and adjust based on the reading.
• An "OL" display indicates the load is too high or the range is insufficient. Stop the measurement or select a higher range.
• Battery voltages exceeding 48V cannot be measured. The meter's internal resistance is low, and such high voltages can cause damage.

Non-Contact Voltage (NCV) Measurement

1. Select Function: Turn the dial to the "NCV" setting. The screen will display "EF".
2. Measurement Method: Test objects by holding the top of the multimeter near them. The meter will beep (?) when it detects an AC signal.

NCV Notes:

• The NCV function detects AC voltage without using test leads.
• The meter operates normally even if the range switch is not in the NCV position when using this function.

Resistance Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the "Ω" setting. Press the "Select" button to choose the resistance mode. The screen will display "MΩ".
3. Connect to Load: Connect the test leads across the component or points where resistance needs to be measured.
4. Record Result: Note the reading on the LCD screen.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Resistance Measurement:

• For resistance values over 1MΩ, it may take a few seconds for the reading to stabilize. This is normal for high resistance tests.
• Do not change the resistance setting during measurement, as it may affect test results or damage the meter.
• Avoid testing in parallel circuits, as this can affect accuracy.
• Do not directly measure the internal resistance of devices like micrometers or galvanometers.
• If the screen displays "OL" (Open Loop), ensure the circuit is powered off and any capacitors are fully discharged before testing internal resistance.

Continuity Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the "Ω" setting (often shared with resistance). Press the "Select" button to choose the continuity mode. The screen will display a continuity symbol (?).
3. Connect to Load: Connect the test leads across the component or points in the circuit.
4. Record Result: If the resistance is below approximately 50Ω, the internal buzzer (?) will sound. If the resistance is above 50Ω, the value will be displayed.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Continuity Measurement:

• A buzzer sound (?) may occur for resistance values between 50Ω and 100Ω. No buzzer will sound for resistance above 100Ω.

Diode Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the diode symbol setting (⚡). Press the "Select" button to choose the diode mode. The screen will display a diode symbol or "OL".
3. Connect to Diode: Connect the red test lead to the positive (anode) terminal of the diode and the black test lead to the negative (cathode) terminal.
4. Record Result: The meter will display the approximate forward voltage drop. If the leads are connected incorrectly or the diode is open, "OL" may be displayed. Change lead positions if "OL" appears.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Capacitance Measurement

1. Connect Test Leads: Black lead to "COM", red lead to "INPUT".
2. Select Function: Turn the dial to the capacitance symbol setting (?️).
3. Connect to Capacitor: Connect the red test lead to the positive terminal of the capacitor and the black test lead to the negative terminal. For non-polarized capacitors, the connection order does not matter.
4. Record Result: Note the reading on the LCD screen.
5. Turn Off: After measurement, turn the dial to the "OFF" position to power off the meter.

Notes on Capacitance Measurement:

• For capacitors exceeding 600µF, readings may take up to 10 seconds to stabilize.
• Ensure correct polarity when connecting test leads to polarized capacitors. Reversing polarity may result in inaccurate readings.

Maintenance

Battery Replacement

When the low battery indicator (?) appears on the screen, replace the batteries promptly.

1. Turn off the meter and disconnect the test leads.
2. Unscrew the back cover of the meter.
3. Remove the old batteries and insert three new AAA (1.5V) batteries, observing correct polarity.
4. Replace the back cover and secure it with screws.

Fuse Replacement

Fuse replacement is uncommon but may occur due to incorrect operation.

1. Turn off the meter and disconnect the test leads.
2. Remove the four screws securing the insulating cover and the back cover.
3. Remove the damaged fuse and replace it with a new fuse of the same specification.
4. Replace the back cover and secure it with screws.

Fuse Specifications:

• Fuse 1: 500 mA / 600V, Ø 5 x 20 mm
• Fuse 2: 10 A / 600V, Ø 5 x 20 mm

Diagram Description: The diagram shows the meter's internal layout for battery and fuse replacement. It illustrates the battery compartment holding three AAA batteries and the locations for Fuse 1 and Fuse 2.

Troubleshooting

Voltage Measurement Issues

• Ensure the dial is set to the correct voltage test setting.
• Connect the black test lead to the ground or ground terminal, and the red test lead to the terminal being measured.
• Check both terminals. One should show a reading, while the other shows 0 or a very low value. A reading on a live wire indicates it is energized.

Diode Functionality

When the red lead is connected to the diode's positive terminal and the black lead to the negative terminal, the meter shows the forward voltage drop. Typical values are 0.5-0.7V for silicon diodes and 0.15-0.3V for germanium diodes. If the leads are connected incorrectly or the diode is open, "OL" may be displayed.

Polarity Identification

• Set the multimeter to resistance mode.
• Connect the test leads to the diode's two terminals.
• Measure the resistance, then swap the test leads and measure again.
• The higher resistance reading indicates reverse bias, and the lower reading indicates forward bias. A lower resistance value is obtained when the black lead is connected to the anode and the red lead to the cathode.

Specifications

General Specifications:

Detailed Specifications:

Accuracy is maintained for one year if stored at 23°C ±5°C.

DC Voltage

• Input Impedance: 10 MΩ
• Overload Protection: 600V DC/AC RMS (400mV range: 250V DC/AC RMS)
• Max Input Voltage: 600V DC

AC Voltage

• Input Impedance: 10 MΩ
• Frequency Range: 40 Hz - 400 Hz
• Overload Protection: 600V DC/AC RMS
• Response: Average, calibrated to RMS for sine wave
• Max Input Voltage: 600V AC RMS

DC Current

• Overload Protection: µA and mA ranges: F0.5A/600V fuse; 10A range: F10A/600V fuse
• Max Input Current: "INPUT" jack: 400mA; "10A" jack: 10A (For measurements >5A, limit to 10 seconds and allow 15 minutes between tests).

AC Current

• Overload Protection: µA and mA ranges: F0.5A/600V fuse; 4A and 10A ranges: F10A/600V fuse
• Max Input Current: "INPUT" jack: 400mA; "10A" jack: 10A
• Frequency Range: 40 Hz - 400 Hz
• Response: Average, calibrated to RMS for sine wave

Resistance

• Overload Protection: 250V DC/AC RMS

Diode and Continuity

• Overload Protection: 250V DC/AC RMS

Capacitance

Battery

• Overload Protection: 1.5V, 9V, 12V ranges: F0.5A/600V fuse. Battery voltage is displayed on the LCD.

Recycling

When disposing of this product, please recycle it in accordance with your local government's laws and regulations for reusable components.

Warranty Period

AstroAI 3-Year Warranty.

All AstroAI True RMS 4000 Count Digital Multimeters are guaranteed to be free from defects in material and workmanship. This warranty excludes fuses, disposable batteries, damage from neglect, misuse, contamination, modification, accidents, or abnormal operating conditions (including failures exceeding the meter's specified voltage ratings or normal wear and tear of mechanical parts).

This warranty applies only to the original purchaser and is non-transferable. If the product is found to be defective, please contact AstroAI Customer Support at support@astroai.com.