FNIRSI DMT-99 Digital Multimeter

1. Introduction

The FNIRSI DMT-99 is an intelligent digital multimeter featuring a 10000-count display, designed for high-resolution and accurate measurements. It is suitable for a wide range of electronic maintenance applications in engineering, laboratories, automotive, and home appliance settings.

This device can accurately measure AC/DC voltage, AC/DC current (up to 10A), resistance, capacitance, frequency, duty cycle, diode, continuity, temperature, Non-Contact Voltage (NCV), and live wire detection. It features a 2.4-inch full-color TFT display with a resolution of 240x320 pixels, supporting a customizable boot interface and a new UI design with a monitoring mode function for enhanced user experience.

2. Package Contents

Please check the package contents upon receipt to ensure all items are present and undamaged:

• DMT-99 Digital Multimeter (1 unit)
• Test Pens (1 set)
• Charging Cable (1 unit)
• User Manual (This document)
• Packaging Box (1 unit)

3. Setup

3.1 Charging the Device

The DMT-99 is equipped with a built-in 1500mAh lithium battery. Before initial use, or when the battery indicator shows low power, charge the device using the provided Type-C charging cable.

1. Connect the Type-C end of the charging cable to the charging port on the multimeter.
2. Connect the USB-A end of the charging cable to a standard USB power adapter (not included) or a computer's USB port.
3. The charging indicator on the device will show the charging status. Ensure the device is fully charged for optimal performance.

3.2 Powering On/Off

Press and hold the power button (usually marked with a circle and a vertical line) to turn the multimeter on or off. The 2.4-inch TFT HD color screen will illuminate upon power-on.

3.3 Test Lead Connection

Insert the test leads into the appropriate input jacks on the multimeter. The black test lead typically connects to the 'COM' (Common) jack, and the red test lead connects to the 'VΩHz' or '10A' or 'mA' jack depending on the measurement type.

4. Operating Instructions

The DMT-99 features an intelligent automatic recognition system for high-precision detection, simplifying measurements without the need for manual gear shifting in many cases.

4.1 Measurement Modes

The DMT-99 offers three major measurement modes:

1. General Mode: This is the standard mode for measuring automatic voltage, resistance, diode/on/off, capacitance, current, frequency, temperature, NCV induced voltage, and LIVE zero live wire.
2. Recording Mode: Allows real-time measurement curve recording, capturing minimum and maximum values during measurement, and saving measurement data.
3. Monitor Mode: When the measured value exceeds or falls below a set threshold, the device's buzzer will sound, and the display screen will provide a prompt.

4.2 Specific Measurement Functions

The DMT-99 supports a comprehensive set of measurement functions:

• AC/DC Voltage: Measure voltage in both alternating and direct current circuits. The True RMS feature ensures accurate AC voltage readings regardless of waveform.
• AC/DC Current: Measure current in both alternating and direct current circuits, up to 10A.
• Resistance: Measure electrical resistance.
• Capacitance: Measure capacitance of components.
• Frequency: Measure the frequency of AC signals.
• Temperature: Measure temperature using the included temperature probe.
• Diode Test: Test the functionality of diodes.
• Continuity Test: Check for continuity in circuits with an audible beep.
• NCV (Non-Contact Voltage) Detection: Detect AC voltage without physical contact, enhancing safety. The display indicates magnetic field intensity.
• LIVE (Live Wire) Detection: Identify live wires for electrical safety.

4.3 Key Design and Operation

The DMT-99 features a button-based design for direct switching, allowing for convenient and efficient one-hand operation, which improves work efficiency compared to traditional knob designs.

• HOLD/REL Button: Press to pause and retain the current measurement data on the display. This is useful for recording readings.
• AUTO/MENU Button: Switches between automatic range detection and manual function selection. Long press to access the menu for advanced settings.
• VΩHz Button: Selects voltage, resistance, or frequency measurement.
• mA/A Button: Selects current measurement (milliamperes or amperes).
• NCV/Hz/LIVE Button: Toggles between Non-Contact Voltage detection, Frequency measurement, and Live wire detection.

4.4 DIY Boot Interface

The DMT-99 supports a DIY boot interface, allowing users to customize the initial display upon powering on the device.

5. Maintenance

5.1 General Care

• Keep the multimeter clean and dry. Wipe the casing with a soft, damp cloth. Do not use abrasive cleaners or solvents.
• Avoid exposing the device to extreme temperatures, high humidity, or direct sunlight.
• Store the device in a cool, dry place when not in use. The storage conditions are -20~60℃ with humidity <80%.
• The device features an ABS anti-drop housing for security protection.
• The back clip design and integrated foldable bracket offer convenient storage and portability.

5.2 Battery Maintenance

The DMT-99 has a built-in 1500mAh lithium battery. Recharge the battery when the low battery indicator appears to ensure continuous operation. Avoid fully discharging the battery for extended periods to prolong its lifespan.

5.3 Overload Protection

The multimeter is equipped with full gear overload protection, including an intelligent anti-burn chip and dual ceramic fuses, to prevent damage from accidental operation. However, always ensure correct measurement ranges and connections to avoid potential hazards.

6. Troubleshooting

If you encounter issues with your FNIRSI DMT-99 multimeter, consider the following basic troubleshooting steps:

• No Display/Power On: Ensure the battery is charged. Connect the charging cable and try powering on again.
• Inaccurate Readings: Check that the test leads are correctly inserted and making good contact. Verify that the measurement mode is appropriate for the task.
• No Continuity Beep: Ensure the continuity test mode is selected and the circuit is complete.
• NCV Not Detecting: Ensure the NCV function is active and the device is brought close enough to the AC voltage source.
• Device Freezes: Try turning the device off and on again. If the issue persists, ensure the battery is adequately charged.

For persistent issues, refer to the official FNIRSI support resources or contact customer service.

7. Specifications

General Specifications:

• Display: 2.4-inch TFT HD Color Screen, 240x320 resolution, 10000 Counts
• Operating Mode: Auto Range
• Battery: 1500mAh Lithium Battery (Built-in)
• Weight: 185g
• Operating Temperature: 0~40℃, humidity <75%
• Storage Conditions: -20~60℃, humidity <80%
• Certification: CE
• Overload Protection: Intelligent anti-burn chip and dual ceramic fuse

8. User Tips

• Always read the full user manual before operating the device to ensure safe and accurate measurements.
• Utilize the 'HOLD' function to freeze readings on the screen, which is particularly useful when working in dimly lit areas or awkward positions where direct screen viewing is difficult.
• Take advantage of the 'AUTO' range feature for general measurements to simplify operation, but switch to manual range when precise control over the measurement scale is required.
• Regularly check the battery level and recharge the device to avoid interruptions during critical measurements.

9. Warranty and Support

For warranty information, technical support, or service inquiries, please refer to the official FNIRSI website or contact your point of purchase. Keep your purchase receipt as proof of purchase.