MASTFUYI FY18D Non-Contact Voltage Tester User Manual

Product Overview

The MASTFUYI FY18D is a versatile non-contact AC voltage detector designed for electrical professionals and DIY enthusiasts. It features an LCD display for real-time monitoring, breakpoint detection, adjustable sensitivity, and audible/visual alarms for enhanced safety and efficiency. This device is ideal for detecting AC voltage, identifying live/neutral wires, and locating circuit breakpoints.

Image: MASTFUYI FY18D Non-Contact Voltage Tester in use, showing detection of neutral (green light) and live (red light) wires in a power strip.

Image: The FY18D voltage tester clipped to a belt, highlighting its portable design.

Safety Information

Before using this instrument, please fully read all safety information carefully and strictly observe the safety rules and the precautions & warnings listed below to avoid possible electric shock or personal injury, and to prevent damage to the Tester or the equipment being tested.

General Safety Guidelines:

• Use the Product only as specified, or the protection supplied by the Product can be compromised.
• Do not use the tester when there is no reaction on the LCD screen.
• Before using the voltage detector, please test a known power supply first to ensure it is in good working condition.
• When using this voltage detector, even if there is no indication or no sound alarm, there may still be a voltage. The results of voltage test may be affected by several factors, including but not limited to shielded wires/cables, thickness and type of insulation, distance from voltage sources, differences in complete insulators, and socket design.
• Before using the tester, inspect the exterior casing. Do not use the tester if it is damaged or if all or part of the exterior casing is removed. Look for cracks or missing plastic. Pay special attention to the insulation around the connectors.
• Do not apply more than the rated voltage, as marked on the voltage detector.
• When the tester pen is working at an effective voltage over 30V rms in AC, special care should be taken because there is a danger of electric shock.
• Comply with local and national safety regulations and use appropriate protective equipment as required by local or national authorities.

Product Structure

Image: Diagram illustrating the components of the FY18D Non-Contact Voltage Tester, including Flashlight, Open key, Temperature/Sensitivity switch, LCD display, Alarm lamp, Protective cover, NCV sensor head, Battery cover, and Pen clip.

1. Probe (NCV sensor)
2. Signal strength indicator - high (red), low (green).
3. LCD display
4. High/low sensitivity conversion button (L/H)
5. Front flashlight & Temperature conversion button (C/F)
6. Power switch button
7. Strong flashlight switch button

Setup and Battery Installation

The FY18D requires 2x1.5V AAA batteries (not included). Ensure batteries are installed correctly before use.

Battery Installation:

1. Locate the battery cover on the device (refer to the Product Structure diagram).
2. Open the battery cover.
3. Insert two 1.5V AAA batteries, ensuring correct polarity (+/-) as indicated inside the compartment.
4. Close the battery cover securely.

Warning: To avoid electric shock, do not use the device before the battery cover is fastened in place.

Operating Instructions

1. Power On/Off

• Turn On: Short press the power switch button. The screen will display the temperature and voltage range.
• Turn Off: The tester will automatically shut down after approximately 5 minutes of inactivity or no voltage signal detection. To manually turn off, long press the power button.

2. Flashlight Operation

• Turn On: When the tester is on, short press the flashlight switch button (button 5 in diagram) to turn on the front flashlight.
• Turn Off: Short press the flashlight switch button again to turn off the flashlight.
• The device also features a strong flashlight switch button (button 7) for additional illumination.

Image: The FY18D voltage tester demonstrating its two-way flashlight lighting feature.

3. AC Voltage Detection

Insert the tester's probe into a power outlet or position it near a live wire. When the tester detects an AC voltage signal, the LCD will display the voltage signal strength. Simultaneously, the buzzer will sound an alarm with varying frequencies based on the detected signal strength.

Image: The FY18D voltage tester detecting voltage in a power outlet, showing visual and audible alerts.

4. Neutral/Live Wire Discrimination

To differentiate between neutral and live wires:

1. Separate the two wires to be tested as much as possible.
2. Use the tester's probe to approach each wire individually. If testing a socket, insert the probe into each jack.
3. The wire that causes a strong detection induction (faster alarm, red light) is the live wire. A weak or absent induction signal indicates the neutral line.

5. Ambient Temperature Measurement

• The default temperature unit at power-on is °C.
• Long press the "C/F" key (button 5 in diagram) to switch the unit to °F.
• Note: This device can only test the temperature of the surrounding environment, not water or food temperature. Do not use this device to test the temperature of water or food to avoid damage to the device.

Image: The FY18D voltage tester displaying the ambient temperature on its LCD screen.

6. AC Voltage Detection Range (Sensitivity Switching)

The device offers two sensitivity modes:

• Low Sensitivity Mode (L): Approx. 48~1000V AC. This is the default mode upon power-on.
• High Sensitivity Mode (H): Approx. 12~1000V AC.

To switch between modes, lightly press the "L/H" button (button 4 in diagram).

Image: A hand pressing the L/H button on the FY18D voltage tester to switch between high and low sensitivity modes.

Recommendation: It is recommended to use low sensitivity mode for detection first. If there is no obvious response (due to thick insulation or other interference), switch to high sensitivity to find the live wires (the red light at the top will be on).

Note on High Sensitivity Mode:

• High-sensitivity mode will give an alarm response within the magnetic field range of a current. This does not mean the tester is broken; its sensitivity is high enough.
• In high sensitivity mode, a green light indicates a neutral wire, and a red light indicates a live wire. The higher the sound frequency, the stronger the current.
• High-sensitivity mode may be disturbed by other electrical appliances within 1 meter, causing alarms. Continue to find the place with the strongest current according to the alarm sound and the current intensity level displayed on the screen.

7. Breakpoint Detection

The FY18D can detect breakpoints in wires. Move the tester along the wire; a change in the detection signal (e.g., from live to no signal) indicates a breakpoint.

Image: The FY18D voltage tester detecting a breakpoint in a wire, illustrating how it identifies live wire, breakpoints, and no electricity.

Maintenance

Battery Replacement:

When the battery voltage is too low, the screen displays a battery symbol. Please replace the batteries promptly.

1. Open the battery cover.
2. Remove the old batteries.
3. Install new 1.5V AAA batteries, ensuring correct positive and negative orientation.
4. Securely close the battery cover.

Warning: To avoid electric shock, do not use the device before the battery cover is fastened in place.

Cleaning:

Wipe the device with a dry, clean cloth. Do not use abrasive cleaners or solvents.

Troubleshooting

• No display or weak response: Check battery level and replace if necessary. Ensure the battery cover is securely closed.
• Inconsistent readings or false alarms in high sensitivity mode: This is normal due to the high sensitivity. Try switching to low sensitivity mode (48-1000V) for initial checks, especially in areas with multiple electrical devices. When in high sensitivity, focus on the strongest signal and alarm frequency to pinpoint the source.
• No detection on a known live wire: Ensure the device is powered on and batteries are good. Try switching to high sensitivity mode (12-1000V) if the insulation is thick or the voltage is low.

Technical Specifications

For a detailed user manual in PDF format, please refer to the official document: MASTFUYI FY18D User Manual (PDF)

Accessories

The product package includes:

• MASTFUYI FY18D Non-Contact Voltage Tester
• User Manual (this document)
• Product Box

Image: Product list showing the FY18D tester, user manual, and product box.

User Tips

• When testing for live wires, always start with the lower sensitivity setting (48-1000V) to avoid false positives in crowded electrical environments. Switch to high sensitivity (12-1000V) only if no clear indication is received.
• The flashlight feature is very useful in dimly lit areas, especially when working inside electrical panels or behind appliances.
• Remember that the ambient temperature sensor is for air temperature only and should not be used for liquids or food.
• For breakpoint detection, slowly move the tester along the wire. The point where the alarm stops or significantly changes indicates a potential break.
• Always ensure the battery cover is fully secured before operating the device to maintain safety and proper function.

Warranty and Support

For warranty information, technical support, or service inquiries, please contact the manufacturer or your point of purchase. Keep your proof of purchase for any warranty claims.