AstroAI AM33B Digital Multimeter User Manual

Introduction

Thank you for purchasing the AstroAI AM33B 2000 Counts Digital Multimeter. AstroAI digital multimeters are designed to safely and accurately troubleshoot a wide range of automotive and home electrical issues in schools, laboratories, factories, and other areas. This manual provides all safety information, operation instructions, detailed specifications, and maintenance procedures for the meter. This instrument performs AC/DC Voltage, DC Current, Resistance, NCV Detection, Battery, Diode, and Continuity Testing.

Thank you again for choosing AstroAI. If you have any questions or concerns regarding your product, please contact AstroAI Customer Support at support@astroai.com.

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

Warning

To avoid possible electric shock, personal injury, and other safety accidents, always adhere to the following rules:

• Please read through this manual before using this multimeter. Failure to follow the instructions may result in damaging or weakening the meter.
• Be cautious when measuring voltages beyond 60 V in DC, 30 V in AC RMS, or 42 V peak. There is a risk of getting shocked when working with these voltages.
• Do not measure voltages higher than the rated value between the terminals or between any terminal and grounding.
• Measure a known voltage to check if the meter is functioning normally. Do not use it if the readings are incorrect or the meter is damaged.
• Before using the meter, inspect it for any defects. Do not use the meter if there are cracks or other damage to the plastic case.
• Inspect the test leads for any defects before using this product. If they are damaged, replace the test leads with those of the same model number and the same electrical specifications as the original.
• Always use this meter within the measurement ranges listed on the meter and in this manual.
• Always comply with local and national safety regulations. Wear personal protective equipment (such as approved rubber gloves, masks, fireproof clothing, etc.) to prevent injury from electrical shocks and electric arcs when hazardous live conductors are exposed.
• To avoid false readings, please replace the battery as soon as the low battery indicator ? appears on the screen. Using the meter with a low battery may cause inaccurate readings.
• Do not use the meter in an environment where explosive gasses/vapors are present, or in high levels of humidity.
• When using the test leads, always keep your fingers behind the finger guards.
• When taking measurements, connect the neutral wire (ground) first. Then, connect the live wire. When disconnecting, remove the live wire first. Then, disconnect the neutral (ground) wire.
• Remove the test leads from the meter before opening its case or battery cover. Do not use the meter if it is disassembled or if the battery cover is open.
• To ensure safe operation, only use the meter with the included test leads. If the test leads are damaged and need to be replaced, they must be replaced with the same model number or identical electrical specifications as the original.

Included in Box

• User Manual × 1
• Pair of Test Leads × 1
• AstroAI 2000 Counts Multimeter × 1

Electrical Symbols

• APO: Automatic Power Off
• DC: DC (Direct Current)
• Full: Full Battery
• Bad: Drained Battery
• -: Negative Reading
• [fuse symbol]: Fuse
• )): Continuity Test
• ▶️: Diode Test
• ⚠️: Warning
• AC: AC (Alternating Current)
• H: Data Hold
• Norm: Normal Battery Level
• Ω: Resistance Test
• ⏚: Earth Ground
• ?: Low Battery
• ☐: Double Insulation
• CE: Compliance with EU Directives

Dimensions

The multimeter has a width of 3.03 inches (7.7 cm) and a height of 5.26 inches (13.35 cm). The depth is 1.46 inches (3.7 cm).

[Diagram showing front and side views of the multimeter with dimensions labeled]

Diagram

The multimeter features the following components:

• 1 Screen: Displays readings and symbols.
• 2 Hold Button: Activates or deactivates the data hold function.
• 3 Rotary Switch: Selects measurement functions and ranges.
• 4 10 A Terminal: For measuring high DC current (up to 10A).
• 5 Backlight Button: Turns the screen's backlight on/off.
• 6 COM Terminal: Common terminal for all measurements.
• 7 VΩmA+ Terminal: For measuring Voltage, Resistance, Continuity, Diode, and low current.
• 8 Test Leads: Used to connect the multimeter to the circuit being tested.

[Diagram showing the front panel of the multimeter with numbered labels pointing to Screen, Hold Button, Rotary Switch, 10A Terminal, COM Terminal, VΩmA+ Terminal, and Test Leads]

Function Buttons

1. Hold Button: Press the HOLD Button to activate or deactivate the data hold function.

2. Backlight Button: Press this button to turn the screen's backlight on/off.

Operating Instructions

Measuring DC/AC Voltage

1. Turn the rotary switch to the DC or AC setting and choose the appropriate voltage range.
2. Insert the red test lead into the VΩmA+ terminal and the black test lead into the "COM" terminal.
3. Connect the test leads to the power supply or the circuit being tested in parallel.
4. The reading will appear on the screen. When measuring DC voltage, the screen will display the polarity of the voltage to which the red test lead is connected.

Warning: To avoid damaging the meter and getting shocked, do not measure voltages exceeding 600 V DC or 600 V AC.

Note: Before using the meter, test the known voltage to confirm the meter is functioning normally.

Measuring DC Current

1. Turn the rotary switch to the DC current setting and choose the appropriate current range.
2. Insert the red test lead into the VΩmA+ terminal (for currents up to 200mA) or the "10 A" terminal (for currents up to 10A) and the black test lead into the "COM" terminal according to the current level to be measured.
3. Disconnect the power supply of the circuit being tested. Connect the meter in series to the circuit being tested. Then, turn on the circuit's power supply.
4. The reading will appear on the screen.

Note: To avoid damaging the meter or equipment, check the fuse before performing measurements and ensure the measured current does not exceed the rated maximum current. Be sure to put the test leads into the correct terminal.

Measuring Resistance

1. Turn the rotary switch to the desired resistance setting (Ω) and choose the appropriate range.
2. Insert the red test lead into the VΩmA+ terminal and the black test lead into the "COM" terminal.
3. Connect the test lead probes to both ends of the circuit or resistor that needs to be measured.
4. The reading will appear on the screen.

Warning: Safely disconnect the power supply and discharge high-voltage capacitors before measuring resistors on a circuit board. Failure to do so may damage the meter and increase the risk of electrical shock.

Note: When measuring resistors on a circuit board, the reading may be affected by other electrical paths between the test leads.

Continuity Test

1. Turn the rotary switch to the Continuity Test setting (symbol: ))).
2. Insert the red test lead into the VΩmA+ terminal and the black test lead into the "COM" terminal.
3. Connect the test lead probes to both ends of the circuit or resistor that needs to be measured.
4. If the resistance value of the measured resistor or circuit is less than 30±20 Ω, the buzzer will beep. The screen will display the resistance value of the resistor or circuit.

Warning: Safely disconnect the power supply and discharge high-voltage capacitors before measuring the meter's continuity. Failure to do so may damage the meter and increase the risk of electrical shock.

Note: When measuring the meter's continuity, the reading may be affected by other electrical paths between the test leads.

Diode Test

1. Turn the rotary switch to the Diode Test setting (symbol: ▶️).
2. Insert the red test lead into the VΩmA+ terminal and the black test lead into the "COM" terminal.
3. Connect the red test lead to the positive end of the diode and the black test lead to the negative end.
4. The reading will appear on the screen.
5. If the polarity of the test leads is the opposite of the diode's polarity, the meter will display "OL", which can be used to distinguish between the anode and cathode of the diode.

Warning: Safely disconnect the power supply and discharge high-voltage capacitors before performing diode tests on the circuit board. Failure to do so may damage the meter and increase the risk of electrical shock.

Note: When performing a diode test on the circuit board, the reading may be affected by other electrical paths between the test leads.

Battery Test

1. Turn the rotary switch to the "BATT" setting and choose the appropriate range (1.5V, 9V, or 12V).
2. Insert the red test lead into the VΩmA+ terminal and the black test lead into the "COM" terminal.
3. Connect the red test lead to the positive end of the tested battery and the black test lead to the negative end.
4. The present voltage reading of the tested battery will appear on the screen.

Note: When measuring 1.5 V and 9 V batteries, the screen will display both the battery voltage and the corresponding battery status (Full, Norm, Bad); however, the screen will only display battery voltage when measuring 12 V batteries.

Auto Power Off

• If the meter is on and not in use, it will shut off after 15 minutes to preserve battery life. Press the HOLD button or turn the rotary switch to turn it back on.
• To cancel the automatic power-off function, press and hold the HOLD Button. Then, turn on the meter. To resume the automatic power-off function, turn off the meter and then turn it back on.

Maintenance

Cleaning the Meter

If the terminals are dusty or wet, incorrect measurements may occur. Please clean the meter as follows:

1. Turn off the meter and remove the test leads.
2. Flip the meter over and shake out any dust that has built up in the terminals. Wipe the case with a damp cloth or mild detergent. Do not use abrasives or solvents. Wipe the contacts in each terminal with a clean cotton swab and alcohol.

Warning: Always keep the inside of the meter clean and dry to prevent electrical shock or damage.

Battery Replacement

1. Turn off the meter and remove the test leads.
2. Remove the screws on the battery cover with a screwdriver. Then, remove the cover.
3. Remove the old battery and replace it with a new battery of the same specification. Pay attention to the polarity of the battery; there are positive (+) and negative (-) polarity markings for each battery in their compartments.
4. Put the battery cover back in its original position and secure the battery cover with its screws.

Warning:

• Replace the battery as soon as it gets low. This will help prevent false readings, electrical shocks, and even injuries. Do not discharge the battery by short-circuiting it or reversing its polarity.
• To ensure safe operation and maintenance of the meter, remove the battery when not used for a long time. Doing so will prevent battery leakage and possible damage to the multimeter.

Fuse Replacement

1. Turn off the meter and remove the test leads.
2. Remove the screws on the meter's back cover. Then, remove the back cover.
3. Remove the blown fuses and replace them with new fuses of the same specification; make sure that the fuse is loaded into the fuse holder and clamped tightly.
4. Put the back cover back on and secure it with the removed screws.

Fuse specifications:

• Fuse 1: F250 mA/250 V, φ 5 x 20 mm
• Fuse 2: F10 A/250 V, φ 5 x 20 mm

Warning: Please use fuses of the same or specified rating to prevent electrical shock, injury, or damage to the meter.

[Diagram showing the back of the multimeter with fuse locations and types labeled: F250 mA/250 V Fuse and F10 A/250 V Fuse]

Specifications

• Environmental Conditions: CAT II 600 V; CAT III 300 V
• Pollution Level: 2
• Altitude: 6562 ft (<2000 m)
• Temperature and Humidity: 32~104 °F (0~40 °C); (<80% RH, <10 °C RH)
• Storage Temperature and Humidity: 14~140 °F (-10~60 °C); (<70% RH, take out battery)
• Temperature Coefficient: 0.1 x Accuracy/°C, <64 °F or > 82 °F (<18 °C or >28 °C)
• Maximum voltage between the measuring terminals and the ground: DC/AC 600 V
• Range Selection: Manual
• Fuse Protection: mA: F250mA/250 V Fuse; 10 A: F10 A/250 V Fuse
• Sample Speed: 3 Times Per Second
• Digital Display: 2000 Counts. The unit symbols will automatically appear according to the measured functions.
• Overload Indication: “OL” Displayed
• Low Battery Indication: The ? symbol will appear when the battery voltage is lower than its normal operating voltage.
• Input Polarity Indication: "-" Automatically Displayed
• Power: 2 x 1.5 V AAA Batteries

Detailed Specifications

DC Voltage

Input Impedance: 10 MΩ

Overload Protection: 600 V DC

AC Voltage

Input Impedance: 10 MΩ

Overload Protection: 600 V AC

Frequency Range: 40 Hz ~ 1 kHz

DC Current

Overload Protection:

• μA/mA: F250 mA/250 V Fuse
• 10 A: F10 A/250 V Fuse

Maximum Input Current: 200 mA; 10 A

When measuring high currents, the continuous measuring time does NOT exceed 15 seconds.

Resistance

Overload Protection: 250 V

Battery Test

Diode Test

Continuity Test

Recycling

You may dispose of the product when its service life has ended. Please recycle the recyclable parts according to local guidelines.

Warranty Period

3-Year Limited Warranty from AstroAI.

Each AstroAI AM33B 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, alterations, accidents, 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 support@astroai.com.