MASTFUYI Digital Multimeter FY105A Instruction Manual

1. Introduction

This instrument is a 3999 count hand-held digital intelligent multimeter. It features fast measurement data, a large screen, reverse display digital LCD, analog bar, lighting, and is easy for users to read. It includes overload protection, battery undervoltage indication, and other functions. Whether used by professionals, factories, schools, enthusiasts, or families, it is an ideal multi-functional instrument. It is designed and produced in accordance with the safety requirements of the International Electrotechnical Safety Standard IEC 61010 for electronic measuring instruments and hand-held digital multimeters.

Figure 1.1: Mastfuyi FY105A Multifunction Multimeter with AC/DC 600V Voltage, AC/DC Current, NCV, Live Wire Detection, Resistance, Continuity, Flashlight, Overload Protection.

1.1 Safety Information

When using this instrument, the user must comply with all standard safety regulations regarding preventing electric shock and preventing incorrect use of instruments. To ensure personal safety, please use the provided test leads and check their condition before use.

1.1.2 Safety Precautions

• When using the instrument near equipment with high electromagnetic interference, readings may be unstable or erroneous.
• Do not use the meter or test leads if their appearance is damaged.
• Incorrect use may compromise the safety functions of the instrument.
• Exercise extreme care when working around exposed conductors or busbars.
• Do not use this instrument near explosive gases, vapors, or dust.
• Always select the correct input, function, and range for measurement.
• The input value must not exceed the specified input limit for each range to prevent damage.
• When the instrument is connected to the test line, do not touch unused inputs.
• Handle with care when measured voltage exceeds 60V DC or 30V AC to prevent electric shock.
• When measuring with test leads, place your finger behind the protective ring.
• Before switching ranges, ensure the test leads have left the circuit under test.
• For all DC functions, first use the AC function to confirm the absence of AC voltage to avoid incorrect readings and electric shock. Then, select a DC voltage range equal to or greater than the AC voltage.
• Before resistance or continuity tests, cut off the power supply and discharge all high-voltage capacitors in the circuit.
• Do not measure resistance or conduct continuity tests on energized circuits.
• When performing TV maintenance or measuring power conversion circuits, avoid damaging the instrument with high amplitude voltage pulses.
• This instrument uses two 1.5V AAA batteries. Ensure they are correctly installed.
• Replace batteries immediately when the low battery symbol appears, as low power can cause incorrect readings.
• When measuring voltage in measurement category III, do not exceed 600V.
• Do not use the instrument if its housing (or part of the shell) is removed.

1.1.3 Safety Symbols

• Δ Warning: Important safety signs, refer to manual. Incorrect use can cause damage.
• ⓘ AC: Alternating Current
• ⓘ DC: Direct Current
• ⓘ ⊥: Grounding
• ⓘ ■■: Double insulation protection

2. Product Features

• Dual Measurement Modes:
  • Auto Mode: Automatically identifies and measures DC/AC voltage, resistance, and continuity.
  • Manual Mode: User-selectable settings for DC/AC voltage, DC/AC current, resistance, and continuity.
• Wide Measurement Range: AC/DC voltage up to 600V, Resistance & Continuity Test, DC/AC Current.
• High-Resolution: 4000 Counts display for precise and reliable measurements.
• User-Friendly Design: Compact, ergonomic body for easy portability, HD LCD with backlight for clear viewing, One-touch Data Hold function, Built-in Flashlight for dark environments, NCV non-contact voltage detection.
• Smart & Safe Operation: Auto Power Off after 10 minutes of inactivity, Low battery indicator.
• Power Supply: Powered by 2xAAA batteries (not included).

Figure 2.1: Two major measurement modes: Auto Mode for automatic measurement of DC voltage, AC voltage, resistance, and continuity; Manual Mode for manual selection of DC voltage, AC voltage, DC current, AC current, resistance, and continuity.

Figure 2.2: High-resolution 4000 Counts display for precise and reliable measurements.

3. Product Overview

3.1 Instrument Diagram

Figure 3.1: Front view of the FY105A Multimeter with key components labeled.

1. Flashlight
2. NCV (Non-Contact Voltage Sensing)
3. LCD Display
4. Flashlight and NCV Button
5. Power On/Off and Function Switching Button
6. Backlight and Data Hold Button
7. Current Input Terminal (A)
8. COM Input Terminal
9. Voltage Input Terminal (V)

3.2 Display Symbol Description

• Δ: Battery under voltage indicator/low battery power. Replace battery when this symbol appears.
• ⓘ AUTO: Indicates automatic range mode.
• ⓘ HOLD: The instrument is in data hold mode.
• ⓘ NCV: The instrument is in non-contact AC voltage detection mode.
• ⓘ LIVE: The instrument is in the live line voltage detection mode.
• ⓘ ℃℉: The instrument is in temperature detection mode.
• ⓘ Ω: The instrument is in resistance detection mode.
• ⓘ ⊥: The instrument is in capacitive detection mode.
• ⓘ Hz: The instrument is in frequency detection mode.
• ⓘ A: The instrument is in current detection mode.

4. Setup

4.1 Battery Installation

The FY105A Multimeter requires two 1.5V AAA batteries (not included). Ensure correct polarity during installation.

Figure 4.1: Battery installation for 2x1.5V AAA batteries.

To replace the battery (refer to Section 8.2 for detailed steps):

• Turn off the instrument and remove all test leads.
• Use a screwdriver to loosen the screw securing the battery cover.
• Remove the cover, replace old batteries with new 2x1.5V AAA batteries, observing polarity.
• Reinstall the battery cover and tighten the screw.

5. Operating Modes

5.1 Automatic Measurement Mode

In Auto Mode, the multimeter automatically measures AC/DC voltage, resistance, and continuity.

1. After powering on, the device automatically defaults to "Auto" measurement mode.
2. Connect the black test lead to the COM input jack and the red test lead to the V input jack.
3. Use the test leads to measure the voltage, resistance, or continuity of the circuit.
4. The LCD will display the corresponding measured values. For DC voltage, the polarity will also be shown.

5.2 Manual Measurement Mode

After powering on, press the SEL button to switch between DC voltage, AC voltage, resistance, ON/OFF (continuity), DC current, and AC current measurement modes.

Figure 5.1: Function Display examples: DC voltage, AC voltage, DC current, AC current, Resistance, and Continuity measurements.

Attention:

• When measuring DC voltage less than 0.5V or AC voltage less than 1V, the displayed resistance value may appear because the minimum measured DC voltage of this product is 0.5V, and the minimum AC voltage is 1V.
• When measuring low current, for accurate results, first short circuit both probes and note the resistance value. Subtract this value from the measured resistance.
• When measuring high resistance, it may take several seconds for the reading to stabilize. This is normal.
• If the instrument is open circuit or the measured resistance is too large, the display will show "OL", indicating the value is out of range.

6. Special Functions

6.1 NCV Test (Non-Contact Voltage Detection)

Briefly press the NCV button and place the top of the instrument close to a conductor. If AC voltage is detected, the instrument will display based on signal strength, and the buzzer will emit varying frequency alarm sounds.

Figure 6.1: NCV Non-Contact Voltage Detection, signaling strength of electric fields with on-screen indicators and buzzer.

Attention:

• Voltage may still exist even without an indication. Do not rely solely on non-contact voltage detectors to determine if a wire is live. Detection can be affected by factors like socket design, insulation thickness, and type.
• If the instrument input terminal has voltage, the buzzer may also sound due to induced voltage.
• External interference (e.g., flash lamps, motors) may suppress non-contact voltage detection.

6.2 Flashlight and Backlight

The multimeter features a built-in flashlight to illuminate measurement points in dark environments. The backlit LCD screen ensures clear readability even in dim lighting conditions.

Figure 6.2: Flashlight function to illuminate measurement points for clear readings in the dark.

Figure 6.3: HD LCD Screen Backlight Display: Sharp and visible values for precise data and quick measurement grasp.

6.3 Data Hold

Press the HOLD button to lock the current reading on the display. Press it again to release.

6.4 Auto Power Off & Low Battery Indication

The device automatically powers down after 10 minutes of inactivity to conserve battery life. A low battery indicator (Δ) will appear on the display when the battery voltage is low, prompting replacement.

Figure 6.4: Smart Power Saving: Multimeter automatically shuts down after 10 minutes of inactivity to conserve energy.

Figure 6.5: Intelligent Power Guardianship: Auto Power Off after 10 minutes of inactivity and Low Battery Indication.

7. Specifications

7.1 General Specifications

• Environmental Conditions: 600V CAT. III, Pollution level: 2, Altitude: 2000 m.
• Working Environment: Temperature: 0-40 ℃ (<80% RH, not considered when <10 ℃).
• Storage Environment: Temperature: -10~50 ℃ (<70% RH, remove battery).
• Temperature Coefficient: 0.1 accuracy/℃ (<18 ℃ or >28 ℃).
• Max Allowable Voltage (between ground): 600V DC or 600V AC RMS.
• Conversion Rate: Approx. 3 times/second.
• Display: 3999 counts LCD display, automatically displaying unit symbols.
• Over Range Indication: "OL" displayed on LCD.
• Low Battery Voltage Indication: "Δ" displayed.
• Input Polarity Indication: Automatically displays a "-" sign.
• Power Supply: 2x1.5V AAA battery.
• Overall Dimension: 118x65x29mm.
• Weight: Approx. 87g (without battery).

7.2 Accuracy Index

Accuracy: ± (a% reading + words). Reference conditions: ambient temperature 18 ℃ to 28 ℃, relative humidity not greater than 80%.

Figure 7.1: Product Parameters table detailing function, range, and accuracy for AC Current, DC Current, AC Voltage, DC Voltage, Resistance, Continuity, NCV, Max Display, Live Wire, Data Hold, Backlight, Flashlight, Auto shut-off, Low Battery Indicator, and Power Supply.

8. Maintenance

This section provides basic maintenance information, including instructions for replacing batteries. Do not attempt to repair this instrument unless you are an experienced maintenance personnel with relevant calibration, performance testing, and maintenance information.

8.1 General Maintenance

Δ To avoid electric shock or damage to the instrument, do not wet the inside of the instrument. Before installing the housing or battery cover, you must remove the test leads and input signal wiring.

• Regularly use a damp cloth and a small amount of detergent to clean the instrument housing. Do not use abrasive or chemical solvents.
• If the input jack is dirty or wet, it may affect the reading. To clean the input jack:
  1. Turn off the instrument and remove all test leads from the input socket.
  2. Remove all dirt from the socket.
  3. Clean each socket with a new cotton ball dipped in a detergent or lubricant that can prevent moisture-related socket contamination.

8.2 Replace the Battery

Δ To avoid electric shock or personal injury caused by incorrect readings, the battery should be replaced immediately when the "Δ" symbol appears on the instrument display.

Δ To avoid electric shock or personal injury, before opening the battery cover and replacing it with a new battery, turn off the power and check that the test leads have been disconnected from the measuring circuit.

Follow these steps to replace the battery:

1. Turn off the instrument power supply.
2. Remove all test leads from the input socket.
3. Use a screwdriver to loosen the screw that secures the battery cover.
4. Remove the battery cover.
5. Remove the old battery.
6. Replace with two new 1.5V AAA batteries, ensuring correct polarity.
7. Install the battery cover and tighten the screws.

9. Troubleshooting

10. User Tips

• Leverage Auto Mode: For quick checks and general measurements, the auto-ranging feature simplifies operation by automatically detecting the measurement type and range.
• Use Backlight in Dim Conditions: Activate the backlight for clear readings in poorly lit environments.
• Flashlight for Precision: The built-in flashlight is invaluable for illuminating specific test points, especially in cramped or dark electrical boxes.
• Data Hold for Convenience: When taking measurements in hard-to-reach places, use the data hold function to freeze the reading on the screen for easier viewing.
• NCV for Initial Safety Check: Always use the NCV function as a preliminary check for live wires before making contact, but always confirm with direct measurement for critical safety tasks.
• Conserve Battery: The auto power-off feature helps save battery life. Remember to turn off the device manually if you're done with it before the auto-off timer.
• Keep Test Leads Clean: Regularly clean your test leads and input jacks to ensure good contact and accurate readings.

11. Warranty and Support

For warranty information, technical support, or service inquiries, please refer to the documentation provided at the time of purchase or contact your retailer. Keep your purchase receipt as proof of purchase.

12. Package Contents

Figure 12.1: Product List: Digital Multimeter Instruction Manual, Smart Digital Multimeter, and Test Leads.

• Operating Instructions (1 copy)
• Test Leads (1 set)