1. Introduction
The GVDA Digital Multimeter is a compact, handheld, 3½ digit multifunction instrument designed for stable performance, high reliability, and anti-drop capabilities. Its circuit design incorporates a large-scale integrated dual-integral A/D converter and overload protection, making it a superior and robust tool for various electrical measurements.
This digital multimeter can measure AC/DC voltage, AC/DC current, resistance, capacitance (GD122, GD123), frequency/duty cycle (GD123), diode and on-off continuity, and non-contact AC voltage (NCV) detection.
2. Safety Information
This digital multimeter is designed according to IEC61010-1-600V (CATIII) and pollution level 2 standards. To ensure accurate and safe use, please read these instructions carefully before operation.
Safety Symbols
- ⚠ Warning: High Voltage hazard.
- ☢ : Non-recyclable.
- ☑ : Double insulation (Class II safety equipment).
- ⚠ : Fuses must be replaced in accordance with specifications.
Use Precautions
- Instruments should only be used with the provided test leads that meet standard requirements. If test leads are damaged, replace them with the same type or equivalent electrical specifications.
- Do not exceed the input limit value specified for each range.
- Do not touch unused input terminals when the instrument is measuring.
- If the size of the measured range is unknown, set the functional range switch to the maximum range position, then gradually reduce it.
- Before switching the functional range switch, ensure the test leads are disconnected from the circuit.
- Before conducting on-line resistance measurement, switch off all power sources in the circuit and discharge all capacitors.
- When measuring voltages above 60V DC and 30V AC, exercise caution and avoid touching the metal parts of the test leads.
- When measuring TV or switching power supply circuits, be aware of potential pulses that could damage the meter.
3. Overview of Components
Familiarize yourself with the main components and controls of your GVDA Digital Multimeter.
GD123 Multimeter with labeled components: NCV sensor, Flashlight, Display, Data hold/Backlight, Frequency/duty cycle button, Lighting button, Function and range gears, 10A jack, COM jack, VQmA jack.
GD122 Multimeter with labeled components: NCV sensor, Flashlight, Display, Data hold, Wake-up meter, Lighting button, Backlight button, Function and range gears, 10A jack, COM jack, VQmA jack.
GD121 Multimeter with labeled components: NCV sensor, Flashlight, Display, Backlight button, Wake-up meter, Lighting button, Data hold, Function and range gears, 10A jack, COM jack, VQmA jack.
General Features
- Display: 3½ Digit LCD Display (GD121: 1999 counts, GD122/GD123: 5999 counts)
- Buttons: Lighting, Backlight, Wake-up, Data Hold
- Switch: Function range switch
- Jacks: VQmA jack, COM jack, 10A jack
- Overload Indication: "OL"
- Polarity Display: Negative pole display "-"
- Low Voltage Indication: Display "⚠"
- Auto Power Off: Yes
- Flashlight: Yes
- HD Backlight: Yes
- Bracket Design: Yes
- Convenient Test Pen Placement: Yes
4. Specifications
General Characteristics
- Maximum voltage between voltage input and ground: CATIII 600V
- Power supply: 3 * 1.5V AAA batteries (not included)
- Working temperature: 0°C to 40°C
- Product size: 147 x 71 x 45mm
- Weight: Approximately 190g (not including battery)
- Certification: CE
- DIY Supplies: Electrical
Measurement Ranges and Accuracy
| Function | Range | Resolution | Accuracy |
|---|---|---|---|
| DC Voltage | 200mV, 2V, 20V, 200V | 0.1mV, 0.001V, 0.01V, 0.1V | ±(0.5% + 2) |
| 600V | 1V | ±(0.8% + 2) | |
| AC Voltage | 200V | 0.1V | ±(1.2% + 10) |
| 600V | 1V | ||
| DC Current | 200µA, 2mA, 20mA | 0.1µA, 0.001mA, 0.01mA | ±(1% + 2) |
| 200mA | 0.1mA | ±(1.5% + 2) | |
| 10A | 0.01A | ±(3% + 2) | |
| Resistance | 200Ω, 2KΩ, 20KΩ, 200KΩ | 0.1Ω, 0.001KΩ, 0.01KΩ, 0.1KΩ | ±(0.8% + 2) |
| 2MΩ | 0.001MΩ | ±(1.0% + 2) |
| Function | Range | Resolution | Accuracy |
|---|---|---|---|
| DC Voltage | 600mV, 6V, 60V, 600V | 0.1mV, 0.001V, 0.01V, 0.1V | ±(0.5% + 2) |
| AC Voltage | 600V | 0.1V | ±(1.2% + 10) |
| DC Current | 60mA, 600mA | 0.01mA, 0.1mA | ±(1% + 2) |
| 10A | 0.01A | ±(3% + 2) | |
| AC Current | 600mA | 0.1mA | ±(1.5% + 2) |
| 10A | 0.01A | ±(3% + 2) | |
| Capacitance | 6000uF | 1uF | ±(5% + 5) |
| Resistance | 600Ω, 6KΩ, 60KΩ, 600KΩ, 6MΩ | 0.1Ω, 0.001KΩ, 0.01KΩ, 0.1KΩ, 0.001MΩ | ±(0.8% + 2) |
| Function | Range | Resolution | Accuracy |
|---|---|---|---|
| DC Voltage | 60mV, 600mV, 6V, 60V, 600V | 0.01mV, 0.1mV, 0.001V, 0.01V, 0.1V | ±(0.5% + 2) |
| AC Voltage | 60mV, 600mV, 6V, 60V, 600V | 0.01mV, 0.1mV, 0.001V, 0.01V, 0.1V | ±(1.2% + 10) |
| DC Current | 600µA, 6000µA, 60mA, 600mA | 0.1µA, 1µA, 0.01mA, 0.1mA | ±(1% + 2) |
| 10A | 0.01A | ±(3% + 2) | |
| AC Current | 600µA, 6000µA, 60mA, 600mA | 0.1µA, 1µA, 0.01mA, 0.1mA | ±(1.5% + 2) |
| 10A | 0.01A | ±(3% + 2) | |
| Capacitance | 9.999nF to 99.99mF | Varies | ±(5% + 5) |
| Resistance | 600Ω, 6KΩ, 60KΩ, 600KΩ, 6MΩ, 60MΩ | 0.1Ω, 0.001KΩ, 0.01KΩ, 0.1KΩ, 0.001MΩ, 0.01MΩ | ±(0.8% + 2) |
| Frequency | 99Hz to 99.99mHz | Varies | ±(0.1% + 2) |
| Duty Cycle | 1% to 99% | 0.1% | ±(0.1% + 2) |
5. Setup
Battery Installation
The multimeter requires 3 x 1.5V AAA batteries (not included) for operation.
- Turn off the meter power and remove the test probes from the input jacks.
- Locate the battery cover on the back of the multimeter.
- Use a screwdriver to remove the screw fixing the battery cover.
- Carefully remove the battery cover.
- Insert three 1.5V AAA batteries, ensuring correct polarity (+ and -).
- Replace the battery cover and secure it with the screw.
Video demonstrating battery installation and various measurement functions.
Image showing the battery compartment for 3 AAA batteries.
Initial Checks
Before using the instrument:
- Turn on the power. If the battery voltage is insufficient, the "⚠" symbol will be displayed on the monitor, indicating that the batteries need replacement.
- Ensure the test leads are in good condition, without any damage to the insulation.
- The "⚠" symbol next to the test lead jack indicates that the input voltage or current should not exceed the specified value to prevent internal circuit damage.
6. Operating Instructions
Always ensure the multimeter is set to the correct function and range before making any measurements.
DC Voltage Measurement
- Insert the red test lead into the "VΩmA" jack and the black test lead into the "COM" jack.
- Set the function range switch to the V= (DC Voltage) range.
- Connect the test leads to the power supply or load to be tested. The polarity of the end connected to the red test lead will be displayed on the LCD.
Warning: If the measured voltage range is unknown, start with the maximum range and gradually decrease it. If "OL" is displayed, the range has been exceeded; select a higher range. Do not input voltage higher than 600V.
DC Current Measurement
- Insert the black test lead into the "COM" jack.
- For currents not exceeding 200mA, insert the red test lead into the "VΩmA" jack. For currents between 200mA and 10A, insert the red test lead into the "10A" jack.
- Set the function range switch to the desired A= (DC Current) range.
- Connect the test meter in series with the load to be tested. The current value and polarity will be displayed.
Warning: The maximum input current is 200mA or 10A depending on the jack used. Exceeding this will burn the fuse. If the measured current range is unknown, start with the maximum range and gradually decrease it. If "OL" is displayed, the range has been exceeded; select a higher range.
AC Voltage Measurement
- Insert the red test lead into the "VΩmA" jack and the black test lead into the "COM" jack.
- Set the function range switch to the V~ (AC Voltage) range.
- Connect the test leads to the power supply or load to be tested.
AC Voltage Measurement in progress.
Resistance Measurement
- Turn the rotary switch to the "Ω" (Resistance) position. The display will initially show "OL" (open circuit).
- Insert the black test lead into the "COM" jack and the red test lead into the "VΩmA" jack.
- Use the test leads to measure the resistance value across the component or circuit.
- Read the measured resistance value from the LCD display.
Note: If the measured resistance exceeds the maximum value of the selected range, "OL" will be displayed. For resistances above 1MΩ, it may take several seconds for the reading to stabilize. When checking on-line resistance, ensure all power is off and capacitors are discharged.
Diode and On-off Continuity Test
- Insert the black test lead into the "COM" jack and the red test lead into the "VΩmA" jack (red lead is positive).
- Set the function range switch to the "→+" (Diode/Continuity) range. The meter will automatically recognize the function.
- Diode Test: Connect the red test lead to the anode and the black test lead to the cathode of the diode. The display will show the approximate forward voltage drop.
- Continuity Test: Connect the test leads to two points of the circuit. If the resistance between the points is less than approximately 50Ω, the built-in buzzer will sound, indicating continuity.
Image showing various functional tests including diode and continuity.
Non-contact AC Voltage Test (NCV)
- Set the function range switch to the "NCV" range. The meter display will show "----".
- Place the top of the meter close to the conductor you wish to test.
- When the detected voltage is greater than 90V (RMS), the buzzer will emit an alarm sound, which will increase in frequency as the meter gets closer to the conductor. The screen will display "---L" for a weak signal and "---H" for a strong signal.
Warning: Even without an indication, voltage may still be present. Do not rely solely on NCV detectors to determine if a conductor has voltage. External interference (e.g., flash, motor) may trigger false positives.
Non-Contact Voltage Detection (NCV) in use.
Live Wire Detecting (GD122 only)
For GD122 models, a dedicated Live Wire Detecting function is available:
- Set the function range switch to the "Live" range.
- Carefully touch the probe to the wire or terminal you suspect is live.
- The meter will indicate the presence of a live wire, typically with an audible alarm and/or a visual indicator on the display.
Live Wire Detecting in use.
Capacitance Measurement (GD122, GD123)
For GD122 and GD123 models, capacitance can be measured:
- Set the function range switch to the capacitance symbol (typically †† or similar).
- Ensure the capacitor is fully discharged before connecting the test leads.
- Connect the test leads across the capacitor terminals.
- Read the capacitance value from the display.
Capacitance measurement in progress.
Frequency and Duty Cycle Measurement (GD123)
For GD123 models, frequency and duty cycle can be measured:
- Set the function range switch to the Hz/% range.
- Connect the test leads to the signal source.
- The display will show the frequency (Hz) or duty cycle (%). Use the 'Hz/%' button to toggle between modes if necessary.
Frequency and Duty Cycle measurement in progress.
Data Hold
Press the "HOLD" button during measurement to freeze the current reading on the display. The symbol "H" will appear on the LCD. Press "HOLD" again to release the data hold and resume normal measurement.
Auto Power Off & Cancel Auto Power Off
- Auto Power Off: If the multimeter is inactive for approximately 10 minutes, it will emit two beeps and enter a dormant state. To wake it up, press any button or rotate the range switch.
- Cancel Auto Power Off: To disable auto power off, press and hold the "HOLD" button while turning on the meter. Release the button after 2 seconds. The auto power off function will be restored the next time the meter is powered on normally.
7. Maintenance
General Care
- Before opening the back cover, ensure the test leads are disconnected from any measurement circuit.
- Do not use the instrument if the back cover is not properly secured with screws.
- Clean the instrument with a damp cloth and a small amount of mild lotion. Do not use chemical solvents on the surface.
- If any abnormalities are observed, immediately cease using the instrument and arrange for inspection or repair.
Battery Replacement
Refer to the Battery Installation section for detailed instructions on replacing the 3 x 1.5V AAA batteries.
8. Troubleshooting
If you encounter issues with your multimeter, try the following common troubleshooting steps:
- No Display / Faint Display: Check the batteries. Replace them if the low battery indicator is on or if the display is dim. Ensure batteries are inserted with correct polarity.
- "OL" Displayed: This indicates an overload or an open circuit. Ensure the measurement range is appropriate for the value being measured. For resistance, it means an open circuit or resistance higher than the selected range.
- Incorrect Readings: Verify that the function range switch is set to the correct measurement type (e.g., AC vs. DC, Voltage vs. Current vs. Resistance). Check that the test leads are securely inserted into the correct input jacks. Ensure the test leads are not damaged.
- No Continuity Beep: Check if the resistance between the two points is above 50Ω. The buzzer only sounds for low resistance connections.
- NCV/Live Wire Detection Not Working: Ensure the meter is close enough to the conductor. External electromagnetic interference can affect detection.
9. User Tips
No specific user tips were available from reviews or Q&A for this product. However, general tips for using multimeters include:
- Always double-check your settings (function, range, probe placement) before making a measurement to avoid damage to the meter or circuit.
- When measuring current, always connect the multimeter in series with the circuit.
- When measuring voltage, always connect the multimeter in parallel with the component.
- For resistance and continuity tests, ensure the circuit is de-energized.
10. Warranty and Support
This product comes with a 1-year warranty on accuracy, as specified in the technical specifications.
For further assistance or technical support, please refer to the official user manual PDF available at: GVDA Digital Multimeter User Manual (PDF). This PDF contains detailed diagrams and additional information that may be helpful.
