AstroAI AM33D Digital Multimeter User Manual

Introduction

Thank you for purchasing the AstroAI digital multimeter. This manual provides safety instructions, usage guidelines, specifications, and maintenance information for the AstroAI AM33D. The multimeter is designed for safe and accurate use in educational, laboratory, and industrial environments, capable of testing AC/DC voltage, DC current, resistance, diodes, and continuity.

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

Please read and fully understand this manual before using the product and keep it for future reference.

Safety Precautions

To prevent electric shock, personal injury, and damage to the meter or tested equipment, follow these rules:

• Use the meter strictly according to this manual.
• Exercise caution when measuring voltages above 60V DC, 30V AC RMS, or 42V peak, as the risk of electric shock increases.
• Do not apply more than the rated voltage to terminals or between terminals and ground.
• Verify normal operation by measuring a known voltage. Do not use if readings are incorrect or the meter is damaged.
• Inspect the meter's plastic casing for cracks or damage before use.
• Use the meter according to its measurement category, voltage, and current ratings indicated on the meter or in the manual.
• Adhere to local and national safety regulations. Wear appropriate Personal Protective Equipment (PPE) such as safety gloves and flame-retardant clothing when working with live conductors that may pose a shock or arc flash hazard.
• Replace the battery as soon as the low battery indicator appears to avoid measurement errors.
• Do not use the meter in the presence of explosive gases, vapor, or humid environments.
• Keep fingers behind the probe guards when testing.
• When measuring, connect the neutral/ground lead first, then the live lead. During disconnection, disconnect the live lead first, then the neutral/ground leads.
• Before opening the battery compartment, remove test leads. Do not use the meter when disassembled or with the battery cover open.
• Use only the supplied test leads. If damaged, replace them with identical ones having the same electrical specifications.

Package Contents

• User Manual x 1
• Pair of Test Leads x 1
• AstroAI Digital Multimeter x 1

Electrical Symbols

• AC (Alternating Current)
• DC (Direct Current)
• V Voltmeter
• A Ammeter
• Square Wave Output
• Double Insulation
• CE Conforms to EU standards
• Low Battery Symbol ?
• Audible Continuity Test ?
• Diode Test ⚡
• Resistance Test Ω
• Ground ⏚
• Warning ⚠️

Diagram

The multimeter features an LCD display, a rotary switch for function selection, a HOLD button, a backlight button, and input terminals.

Key Components:

• 1) LCD Display
• 2) OFF position
• 3) HOLD Button
• 4) DC Voltage Test
• 5) Rotary Switch
• 6) Resistance
• 7) 10 A Terminal
• 8) VΩmA¬ Terminal
• 9) Backlight Button
• 10) AC Voltage Test
• 11) DC Current Test
• 12) Square Wave Output
• 13) Continuity Test / Diode Test
• 14) COM Terminal
• 15) Test Leads

Dimensions

Width: 7.3 cm (2.87 inches)

Height: 13.0 cm (5.12 inches)

Depth: 3.7 cm (1.46 inches)

Function Buttons

• HOLD Button: Press to freeze the current reading or clear data.
• Backlight Button: Press to activate the screen backlight for low-light conditions. It will dim and turn off automatically.
• 10A MAX Terminal: Insert the red test lead into the 10 A terminal for DC current measurements up to 10 A.
• VΩmA¬ Terminal: Insert the red test lead into this terminal for functions other than 10 A current measurements.
• COM Terminal: Insert the black test lead into the COM terminal.

Preparation

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the Continuity Test position. Touch the test leads together; a buzzer should sound if they are functioning correctly.

Instructions

DC Voltage Measurement

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the "V=" range (white lettering). The display will show "000", indicating DC voltage measurement mode.
3. Connect the test leads in parallel to the power source or circuit being tested.
4. Wait for the reading to stabilize, then record it from the LCD.
5. Turn the rotary switch to "OFF" to power down the meter.

Note: If the reading is preceded by "m", the unit is "mV". If "HV" is displayed, the voltage is high (e.g., 600V range).

AC Voltage Measurement

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the "V~" range (white lettering). The display will show "000", indicating AC voltage measurement mode.
3. Connect the test leads in parallel to the power source or circuit being tested.
4. Wait for the reading to stabilize, then record it from the LCD.
5. Turn the rotary switch to "OFF" to power down the meter.

Note: If "HV" is displayed, the voltage is high (e.g., 600V range).

DC Current Measurement (10 A)

1. Disconnect the power from the circuit under test.
2. Insert the black test lead into the "COM" terminal and the red test lead into the "10 A" terminal.
3. Turn the rotary switch to the "10 A" setting in the "A-" range. The display will show "000", indicating DC current measurement from 200 mA to 10 A.
4. Connect the multimeter in series with the circuit and then turn on the circuit's power.
5. Wait for the reading to stabilize, then record it from the LCD.
6. Turn the rotary switch to "OFF" to power down the meter.

Note: Start with the 10 A setting if the current is unknown. After initial measurement, select a more appropriate range based on the actual current.

DC Current Measurement (mA/µA)

1. Disconnect the power from the circuit under test.
2. Turn the rotary switch to the "A=" range (yellow lettering) for 2000 µA to 200 mA. The display will show "000".
3. Connect the multimeter in series with the circuit and then turn on the circuit's power.
4. Wait for the reading to stabilize, then record it from the LCD.
5. Turn the rotary switch to "OFF" to power down the meter.

Note: Readings may be displayed in µA, mA, or A depending on the selected range.

Resistance Measurement

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the "Ω" range (yellow lettering). The display will show "1", indicating resistance measurement mode.
3. Connect the test leads in parallel across the component or circuit being tested.
4. Wait for the reading to stabilize, then record it from the LCD.
5. Turn the rotary switch to "OFF" to power down the meter.

Note: Readings may be displayed in Ω, kΩ, or MΩ. A low resistance (below 50Ω) will trigger the buzzer. If the circuit or resistor is disconnected, or the resistance is above 300±200Ω, the LCD will show "1".

Continuity Test

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the continuity test setting (symbol ?). Touch the test leads together; the buzzer will sound if they are functioning correctly.
3. Connect the test leads in parallel to the component or circuit. If the resistance is below 30±200Ω, the buzzer will sound.
4. If the circuit/resistor is disconnected, or resistance is above 300±200Ω, the LCD will show "1".
5. Turn the rotary switch to "OFF" to power down the meter.

Diode Test

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Connect the red test lead to the anode and the black test lead to the cathode of the diode.
3. The LCD will display the forward voltage drop of the diode in "mV". If leads are reversed, the LCD will show "1". Reverse leads and repeat the measurement.
4. Turn the rotary switch to "OFF" to power down the meter.

Square Wave Output

1. Insert the red test lead into the "VΩmA" terminal and the black test lead into the "COM" terminal.
2. Turn the rotary switch to the "OUT" setting (symbol ⏚). The display will show "1", indicating square wave output mode.
3. Connect the test leads in parallel to the power source or circuit.
4. Wait for the reading to stabilize, then record it from the LCD.
5. Turn the rotary switch to "OFF" to power down the meter.

Maintenance

Cleaning the Meter

1. Turn off the meter and remove test leads.
2. Turn the meter upside down and shake to dislodge dust from terminals. Clean the meter casing with a damp cloth or one with mild detergent. Clean terminal contacts with an alcohol-moistened cotton swab.

Battery and Fuse Replacement

Battery Replacement

1. Turn off the meter and remove test leads.
2. Unscrew the battery compartment cover with a screwdriver and remove the cover.
3. Remove the old battery and replace it with a new one of the same specifications (Type: 1 x 9V NEDA 1604 / 6F22 / 006P).
4. Replace the battery cover in its original position and secure it with the previously removed screws.

Fuse Replacement

1. Turn off the meter and remove test leads.
2. Unscrew the battery compartment cover with a screwdriver and remove the cover and battery.
3. Remove the insulating sleeve and screws on the back of the meter.
4. Replace blown fuses with ones of the same specifications. Ensure fuses are securely seated in their respective holders.
5. Replace the insulating cover, battery, and battery cover, then secure with the previously removed screws.

Fuse Specifications:

• Fuse 1: F500 mA / 600V (Size: 5 x 20 mm)
• Fuse 2: F10 A / 600V (Size: 5 x 20 mm)

Specifications

• Digital Display: 20000, 3 1/2 digits
• Sampling Rate: 2 times/second
• LCD Screen Dimensions: 49 x 17 mm
• Range Selection: Manual
• Polarity Indication: "-" displayed automatically
• Overload Indication: "1" displayed
• Low Battery Indication: ? displayed when battery voltage is low
• Operating Conditions: 0~40 °C, <80% RH
• Storage Temperature: -10~50 °C, <85% RH
• Power Supply: 1 x 9V NEDA 1604 / 6F22 / 006P battery
• Weight: Approx. 145 g
• Dimensions: 130 x 73 x 37 mm

Detailed Specifications

Accuracy is guaranteed for 1 year under storage conditions of 23 °C ± 5 °C, with less than 80% RH.

DC Voltage

AC Voltage

DC Current

Measured voltage drop: 200mV

Resistance

Maximum open circuit voltage: 3 V

Continuity Test

Recycling

Dispose of the product responsibly at the end of its useful life. Please recycle recyclable parts according to local guidelines.

Warranty Period

3-Year Limited Warranty from AstroAI

Each AstroAI digital multimeter is free from defects in material and workmanship. This warranty does not cover fuses, disposable batteries, or damage resulting from negligence, misuse, contamination, alteration, accidents, or abnormal operating conditions, including overvoltage damage from use outside specified ratings or normal wear and tear of mechanical components.

This warranty covers only the original purchaser and is non-transferable.

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