MASTFUYI Digital Multimeter User Manual

1. Introduction

Thank you for choosing the MASTFUYI Digital Multimeter. This high-precision instrument is designed for professional measurement, offering True RMS capabilities, smart safety features, and multi-functional versatility. Please read this manual carefully before use to ensure safe and effective operation.

Key Features:

• High-Precision Measurement: 9999 Counts True RMS for accurate readings of non-sinusoidal AC waves.
• Smart Safety Protection: Non-Contact Voltage Detection (NCV) with dual alarm modes, ceramic fuse, and anti-burn chip with overload auto-shutdown.
• Multi-Functional Versatility: Measures AC/DC Current, AC/DC Voltage, Capacitance, Resistance, Frequency, Temperature, Diode, Continuity, and Live Wire.
• User-Friendly Design: Backlit color screen, built-in flashlight, auto power-off, and low battery indication.
• Power Options: Rechargeable Li-ion battery (FY159B/FY158B) or AAA batteries (FY158A).

2. Safety Information

▲ WARNING: Improper use may cause electric shock or damage to the meter. Please read and follow all safety instructions carefully.

2.1 General Safety Precautions

• Always use the measurement probes accompanying the meter and ensure they are in good condition before use.
• Do not use the meter or measurement probes if there is any visible damage.
• Incorrect use may compromise the safety functions of the meter.
• Exercise extreme caution when working around exposed conductors or busbars.
• Do not use this meter near explosive gas, steam, or dust.
• Ensure measurements are performed using the correct input, function, and range.
• To prevent damage, the input value must not exceed the specified limit for each range.
• Never touch unused input terminals when the meter is connected to the circuit under test.
• Operate with care to prevent electric shock when the measured voltage exceeds 60V DC or 30V AC RMS.
• Place your fingers behind the measurement probe's protective ring when measuring.
• The meter may produce unstable or erroneous readings when used near devices with strong electromagnetic interference.

2.2 Safety Symbols

• ▲ Warning: Important safety sign, consult instruction manual before use.
• AC: Alternating Current
• DC: Direct Current
• AC/DC: Alternating or Direct Current
• ⏚: Ground
• CE: Compliant with EU (European Union) directives

2.3 Environmental Conditions of Use

• Pollution Grade: 2
• Altitude: < 2,000 m
• Working Temperature & Humidity: 0°C to 40°C (<80% RH, neglected when <10°C)
• Storage Temperature & Humidity: -10°C to 50°C (<70% RH, with battery removed)
• Temperature Coefficient: Accurate to 0.1/°C (<18°C or >28°C)
• Maximum Allowable Voltage: Between measuring terminal and earth: 600V DC or 600V AC RMS.

3. Product Overview

3.1 Meter Layout (FY159B shown)

1. Non-contact voltage sensing (NCV Probes)
2. Flashlight
3. LCD Monitor
4. Power Button (Turn On/Off)
5. Select Function Button (SEL)
6. Flashlight and Data Hold Button (HOLD)
7. NCV and High/Low Sensitivity Toggle Key (H/L NCV)
8. Current Input Terminal (10A)
9. COM Input Terminal
10. VΩCPFHZ Live Input Terminal

3.2 Display Symbols

4. Setup

4.1 Battery Installation (for FY158A)

The FY158A model requires 3x 1.5V AAA batteries (not included). Follow these steps:

1. Power off the meter and unplug all test probes.
2. Loosen the screws securing the battery cover on the back of the meter with a screwdriver.
3. Remove the battery cover.
4. Insert 3x 1.5V AAA batteries, observing correct polarity.
5. Replace the battery cover and tighten the screws.

4.2 Battery Charging (for FY158B/FY159B)

The FY158B and FY159B models are equipped with a 1000mAh rechargeable lithium battery and feature a USB-Type-C charging port. Follow these steps to charge:

1. Power off the meter and unplug all test probes.
2. Loosen the screws securing the battery cover on the back of the meter with a screwdriver.
3. Connect the provided USB-Type-C charging cable to the meter's charging port and a suitable USB power source.
4. A red indicator light will illuminate during charging.
5. The light will turn green when the battery is fully charged.
6. Replace the battery cover and tighten the screws.

5. Operating Instructions

5.1 Power On/Off

• Short press the power button () to turn the meter on. It will typically enter 'Auto' mode.
• Short press the power button again to turn the meter off.
• The meter features an auto power-off function after 15 minutes of inactivity to conserve battery.

5.2 Auto Measurement Mode

When powered on, the meter defaults to 'Auto' mode, automatically recognizing and measuring AC/DC voltage, resistance, and continuity.

5.3 Manual Function Selection

Press the SEL button to cycle through different measurement functions:

• Capacitance: Measures capacitance.
• Diode: Tests diodes.
• LIVE: Live wire detection.
• NCV: Non-Contact Voltage detection.
• Temperature: Measures temperature (requires thermocouple probe for FY159B).
• Frequency: Measures frequency.
• AC/DC Current: Measures current (for FY159B).

5.4 Data Hold & Flashlight

• Data Hold: Short press the HOLD button to lock the current reading on the display. Press again to release.
• Flashlight: Long press the HOLD button to turn the built-in flashlight on or off.

5.5 Non-Contact Voltage (NCV) Detection

The NCV function allows for safe detection of AC voltage without direct contact. Press the NCV button to enter this mode.

• Sensitivity: Press the H/L NCV button to toggle between low ('LO') and high ('HI') sensitivity.
• When voltage is detected, the meter will emit a buzzer sound and the warning light will flash.

5.6 Live Wire Check

Use the LIVE function to identify live wires in outlets or cables.

• Connect the red test lead to the VΩCPFHZ input terminal and the black test lead to the COM terminal.
• Insert the red test lead into the socket or touch the wire.
• A strong alarm and visual indication will occur for a live wire, while no response is provided for a neutral line.

5.7 Measurement Examples

The video above demonstrates various measurement functions. Here are some common measurements:

• DC Voltage: Connect probes to the DC source. The meter will display the voltage.
• AC Voltage: Connect probes to the AC source. The meter will display voltage and frequency.
• DC Current: Connect the meter in series with the DC circuit.
• AC Current: Connect the meter in series with the AC circuit.
• Resistance: Connect probes across the component.
• Continuity: Touch probes to both ends of a circuit. A buzzer indicates continuity.
• Capacitance: Connect probes across the capacitor.
• Diode: Connect probes across the diode. The meter displays the forward voltage drop.
• Temperature: Connect the thermocouple probe (for FY159B) to the meter and place the sensor at the measurement point.

6. Specifications

The following table outlines the technical specifications for the MASTFUYI Digital Multimeter series. Note that specifications may vary slightly between models (FY158A, FY158B, FY159B).

General Specifications:

• Conversion Rate: Approximately 3 times/second
• Display: LCD display, unit symbol automatically displayed.
• Overload Indication: LCD will display "OL".
• Battery Low Voltage Indication: "" will appear.
• Input Polarity: "-" is displayed automatically.
• Dimensions: Approx. 162×47×26mm (FY158A/B), 165x80x25mm (FY159B)
• Weight: Approx. 107g (FY158A/B without battery), 125g (FY159B with battery)
• Overload Protection: 250V DC/AC (for most functions), 600V/10A Fuse (for current measurements on FY159B).

7. Maintenance

7.1 General Maintenance

• Clean the meter case regularly with a damp cloth and a small amount of mild detergent. Do not use abrasives or chemical solvents.
• Avoid moisture inside the meter. Before opening the case or battery cover, always disconnect the measurement probes from any input signals.
• Dirty or wet input jacks can affect readings.

7.2 Cleaning Input Jacks

1. Turn off the meter and unplug all measurement probes.
2. Remove any visible dirt from the jacks.
3. Clean each jack socket with new cotton balls dipped in detergent or lubricant. Lubricant can help prevent moisture-related contamination.

7.3 Battery Replacement/Recharge

▲ WARNING: Replace or recharge the battery immediately when the battery symbol appears on the display to avoid electric shock or personal injury due to incorrect readings. Always power off the meter and disconnect test probes before opening the battery cover.

• For FY158A (AAA Batteries): Follow the battery installation steps in Section 4.1.
• For FY158B/FY159B (Rechargeable Lithium Battery): Follow the battery charging steps in Section 4.2.

8. Troubleshooting

If you encounter issues with your multimeter, consider the following common troubleshooting steps:

• No Display/Faint Display: Check battery level. Replace AAA batteries (FY158A) or recharge the lithium battery (FY158B/FY159B).
• Unstable Readings: Ensure test leads are securely connected. Move away from strong electromagnetic interference.
• No Response in a Specific Mode: Verify that the correct function is selected for the measurement. Check if the input terminals are correctly used for the selected function.
• Overload Indication ("OL"): The input value exceeds the meter's range. Disconnect immediately and select a higher range or a different meter if necessary.
• Meter Does Not Turn On: Ensure batteries are correctly installed/charged. Press and hold the power button for a few seconds.

If problems persist, discontinue use and consult professional assistance.

9. User Tips

Choosing the Right Model:

Users often inquire about the differences between the models. The primary distinctions lie in their measurement capabilities and power supply:

• FY159B: Offers the most comprehensive features, including AC/DC Current measurement, wider Resistance and Capacitance ranges, Temperature measurement, and a 9999-count display. It uses a rechargeable 1000mAh Li-ion battery.
• FY158B: A mid-range option with 5999 counts, similar voltage, resistance, and capacitance ranges to FY158A, but lacks AC/DC Current and Temperature measurement. It uses a rechargeable 1000mAh Li-ion battery.
• FY158A: The basic model with 5999 counts, lacking AC/DC Current and Temperature measurement. It is powered by 3x 1.5V AAA batteries.

Refer to the detailed comparison table in Section 6. Specifications for a complete overview.

10. Warranty and Support

The warranty period for this product is one year from the date of delivery. For specific warranty claims, technical support, or service inquiries, please contact your retailer or the manufacturer directly. Keep your purchase receipt as proof of purchase.

11. Package Contents

The contents of your package may vary slightly depending on the specific model purchased. Please check the packaging for the exact list of items.

Typical Contents:

• Digital Multimeter (FY158A, FY158B, or FY159B)
• User Manual
• Test Probes (one set)
• Storage Bag

Model-Specific Additions:

• FY158A: No additional items beyond typical.
• FY158B: USB Type-C Cable
• FY159B: USB Type-C Cable, Thermocouple Probe