1. Safety Information
Before using the instrument, please read this manual carefully and save it well for future use. Pay special attention to all safety warnings and instructions.
1.1 Safety Statement
⚠ Caution:
Indicates an operation that may cause damage to the meter or equipment.
⚠ Warning:
Indicates an operation that may cause danger to users.
1.2 Safety Instructions
The meter conforms to IEC61010-1 CAT.III 600V overvoltage safety standard and pollution level 2.
⚠ Warning:
To avoid possible electric shock or personal injury, please observe the following specifications:
- Please read this manual carefully and pay special attention to safety warning information before using the meter.
- Operate the meter according to the manual, otherwise the protection function provided by the instrument may be damaged or weakened.
- Take special care when measuring values that exceed 60VDC, 30VAC RMS, or 42V. This kind of voltage has the danger of electric shock.
- Do not measure voltage higher than the rated value between terminals or between terminals and ground.
- Measure a known voltage to check whether the meter works normally. If it is not normal or damaged, do not use it again.
- Before using the meter, please check whether there are cracks or damaged plastic parts in the instrument shell. If so, do not use it again.
- Before using the meter, please check whether the probe is cracked or damaged. If so, please replace the probe with the same model and the same electrical specification.
- Please use the meter according to the measurement category, voltage or current rating specified in the meter or manual.
- Please observe local and national safety regulations. Wear personal protective equipment (such as approved rubber gloves, masks and flame retardant clothing, etc.) to prevent injury caused by electric shock and electric arc when dangerous live conductors are exposed.
- When the low battery symbol (🔋) is displayed on the meter, please replace the battery in time to prevent measurement error.
- Do not use the meter in an environment with explosive gas or steam or a humid environment.
- When using the probe, please hold your fingers behind the probe finger guard.
- When measuring, please connect the null or ground wire first, then the live wire; when disconnected, please disconnect the live wire first, and then the null or ground wire.
- Remove the probe from the meter before opening the case or battery cover. Do not use the meter when the meter is disassembled or the battery cover is opened.
- The meter can only be used together with the probe provided to meet the requirements of the safety standard. If the probe is damaged and needs to be replaced, the probe of the same model and electrical specification must be replaced.
2. Product Overview
The GVDA GD120B is an intelligent True RMS digital multimeter designed for accurate and reliable electrical measurements. It features intelligent auto-ranging capabilities and a professional measurement function, complete with a gear display and an analog bar for multiple displays.
2.1 Components
- Alarm indicator
- Display
- Function key
- Current input jack
- COM input jack
- Input jack for other functions except current
- NCV Sensor area
- Flashlight
3. Setup
3.1 Battery Installation
The GD120B multimeter requires 4 AAA batteries (not included) for operation. Follow these steps to install or replace batteries:
- Turn off the meter power and remove the probes.
- Remove the screw fixing the battery cover on the back of the device and remove the battery cover.
- Remove the old batteries (if any) and replace them with new 4x 1.5V AAA batteries of the same specification. Pay attention to the correct battery polarity.
- Install the battery cover back to its original position, and fix and lock the battery cover with screws.
⚠ Warning:
- To avoid electric shock or personal injury caused by wrong reading, please replace the battery immediately when the battery is low.
- Do not discharge the battery by shorting it or reversing its polarity.
- To operate and maintain the meter safely, please take out the battery when it is not used for a long time to prevent battery leakage from damaging the product.
3.2 Probe Connection
Always ensure probes are correctly connected to the appropriate input jacks for the desired measurement. The red probe connects to the positive (+) terminal, and the black probe connects to the common (COM) terminal.
4. Operating Instructions
4.1 Power On/Off
Press and hold the power button (⏻) for about 2 seconds to turn the multimeter on or off.
4.2 Gear Selection
Press the FUNC button to switch to manual mode and cycle through different measurement functions. Press the SMART button to return to the intelligent (AUTO) measurement mode. The meter defaults to intelligent measurement mode upon power-on.
4.3 Data Hold
Press the H button to turn on or off the data holding function, which freezes the current reading on the display.
4.4 Flashlight and Backlight
Press and hold the SEL/💡 button for about 2 seconds to turn the flashlight on or off. Press the H/* button to turn the backlight on or off. Note: VA display does not have this function.
4.5 Input Jack Indicator
When the measurement gear is changed, the corresponding input light will flash 5 times to prompt the user to insert the probe into the correct jack.
4.6 Automatic Current Identification Function
When the "A" jack is inserted into the probe, the meter will automatically jump to the current measurement gear and enter the current measurement function.
4.7 Auto Power Off
After power on, auto power off is enabled by default, indicated by the auto power off symbol (⏻) on the display. Without any key operation for about 15 minutes, the meter will automatically shut down to save battery energy. Press and hold the SEL/💡 key to turn on the meter, and the auto power off function will be canceled.
4.8 Measurement Operations
⚠ Warning:
- Do not measure voltage higher than 600V; otherwise, the meter may be damaged.
- Pay special attention to safety when measuring high voltage to avoid electric shock or personal injury.
- Before use, test a known voltage with the meter to confirm that the meter is in good condition.
4.8.1 Smart (AUTO) Measurement
This is the default measurement mode when powered on. In this mode, DC voltage, AC voltage, resistance, and continuity can be measured, and the meter automatically identifies the measurement signal.
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured power supply or resistance (in parallel). The meter will automatically recognize the measured signal.
- When measuring resistance, if the value is less than about 50 Ω, the buzzer sounds and the indicator light is on.
- Read the results from the display.
NOTE: The minimum measurable voltage in this mode is 0.8V.
Video 4.1: Demonstration of various measurement functions including Smart mode, DC voltage, resistance, AC voltage, diode test, capacitance, frequency, temperature, NCV, and live wire detection.
4.8.2 AC/DC Voltage Measurement
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the voltage measurement gear (V).
- Press the SEL/💡 key to select AC voltage (displaying "AC" symbol) or DC voltage (displaying "DC" symbol).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured power supply (in parallel).
- Read the results from the display.
4.8.3 Resistance Measurement
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the resistance measurement gear (Ω).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured resistance (in parallel).
- Read the results from the display.
4.8.4 Continuity Test
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the continuity test gear (🔊).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured resistance or circuit (in parallel).
- When the resistance value is less than about 50 Ω, the buzzer sounds and the indicator light is on.
- Read the results from the display.
4.8.5 Frequency/Duty Measurement
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the frequency/duty measurement gear (Hz%).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured power supply.
- Read the results from the display.
4.8.6 Capacitance Measurement
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the capacitance measurement gear (F).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- Contact the probes to both ends of the measured capacitance (in parallel).
- Read the results from the display.
4.8.7 Diode Test
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the diode test gear (▶|).
- Insert the red probe into the HzVΩLive jack and the black probe into the COM jack.
- The red probe contacts the anode of the diode and the black probe contacts the cathode of the diode.
- If the probe polarity is opposite to the diode polarity, the display will show "OL".
- Read the results from the display.
4.8.8 Temperature Measurement
This function requires a K-type thermocouple probe (often included).
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the temperature measurement gear (°C/°F).
- Insert the positive pole of the K-type thermocouple into the HzVΩLive jack and the negative pole into the COM jack.
- The thermocouple probe contacts the measured object.
- Read the results from the display.
4.8.9 Non-contact AC Voltage Detection (NCV)
This feature allows detection of AC voltage without direct contact.
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the NCV gear. The display will show the "NCV" symbol.
- Gradually move the NCV sensor area (top of the multimeter) close to the conductor.
- When a weak electric field signal is detected, it will display "---L"; the buzzer will sound slowly and the green light on.
- When a strong electric field signal is detected, it will display "---H"; the buzzer will sound quickly and the red light on.
4.8.10 Live Wire Detecting
This function helps identify live wires.
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the Live gear.
- Insert the red probe into the HzVΩLive jack and remove the black probe.
- Use the red probe to contact the conductor.
- When a weak electric field signal is detected, it will display "---L"; the buzzer will sound slowly and the green light on.
- When a strong electric field signal is detected, it will display "---H"; the buzzer will sound quickly and the red light on.
4.8.11 AC/DC Current Measurement
⚠ Caution:
Do not measure current greater than 10A, otherwise the fuse will be burnt out.
- Press the power button (⏻) to power on. The display will show "Auto" and enter the intelligent measurement mode.
- Press the FUNC key to select the current measurement gear (A). Alternatively, insert the red probe into the A jack to automatically select the current gear.
- Press the SEL/💡 key to select AC current (displaying "AC" symbol) or DC current (displaying "DC" symbol).
- Insert the red probe into the A jack and the black probe into the COM jack.
- Disconnect the measured power supply, connect the meter in series with the power supply, and then turn on the measured power supply.
- Read the results from the display.
5. Specifications
5.1 General Technical Specifications
- Overvoltage Category: CAT. III 600V
- Pollution Level: 2
- Altitude: < 2000m
- Working Temperature and Humidity: 0~40°C (<80% RH, <10°C non-condensing)
- Storage Temperature and Humidity: -10~60°C (<70% RH, remove the battery)
- Temperature Coefficient: 0.1x accuracy /°C (<18°C or >28°C)
- MAX. Voltage between terminals and earth ground: DC/AC 600V
- Fuse Protection: F10A/250V fuse
- Sampling Rate: Approx. 3 times/second
- Display: 6000 counts
- Over Range Indication: "OL"
- Low Battery Indication: 🔋 symbol will be displayed
- Input Polarity Indication: Display "-"
- Power Requirement: 4 x 1.5V AAA batteries
5.2 Accuracy Specifications
The accuracy applies within one year after calibration. Reference condition: environment temperature 18°C to 28°C, relative humidity no more than 80%.
DC Voltage
| Range | Resolution | Accuracy |
|---|---|---|
| 600mV | 0.1mV | ±(0.5%+3) Impedance: Approx. 10MΩ |
| 6V | 0.001V | |
| 60V | 0.01V | |
| 600V | 1V |
AC Voltage
| Range | Resolution | Accuracy |
|---|---|---|
| 6V | 0.001V | ±(0.8%+3) |
| 60V | 0.01V | |
| 600V | 1V | |
| Impedance: Approx. 10MΩ | ||
| Frequency Response: 40Hz~1kHz; TRMS | ||
Resistance
| Range | Resolution | Accuracy |
|---|---|---|
| 600 Ω | 0.1 Ω | ±(1.0%+5) |
| 6KΩ | 0.001 KΩ | |
| 60 KΩ | 0.01 KΩ | |
| 600 KΩ | 0.1 KΩ | |
| 6MΩ | 0.001 MΩ | ±(1.5%+10) |
| 60 MΩ | 0.01 MΩ | |
| Overload protection: 250V | ||
AC/DC Current
| Range | Resolution | Accuracy |
|---|---|---|
| 600mA | 0.1mA | ±(1.2%+3) |
| 6A | 0.001A | |
| 10A | 0.01A | |
| Overload protection: F10A/250V fuse | ||
| Frequency Response: 40Hz~1kHz; TRMS | ||
Capacitance
| Range | Resolution | Accuracy |
|---|---|---|
| 6nF | 0.001nF | ±(4.0%+5) |
| 60nF | 0.01nF | |
| 600nF | 0.1nF | |
| 6μF | 0.001μF | |
| 60μF | 0.01μF | |
| 600μF | 0.1μF | |
| 6mF | 0.001mF | ±(5.0%+5) |
| 60mF | 0.01mF | |
| Overload protection: 250V | ||
Frequency/Duty
| Range | Resolution | Accuracy |
|---|---|---|
| 6Hz | 0.001Hz | ±(1.0%+3) |
| 60Hz | 0.01Hz | |
| 600Hz | 0.1Hz | |
| 6KHz | 0.001KHz | |
| 60kHz | 0.01kHz | |
| 600kHz | 0.1kHz | |
| 6MHz | 0.001MHz | |
| 10MHz | 0.01MHz | |
| 1.0~99.0% | 0.1% | ±(1.0%+3) |
| Overload protection: 250V | ||
Diode/Continuity
| Function | Description |
|---|---|
| Diode Test | Display diode voltage drop |
| Continuity | Approx. 50Ω, Buzzer will sound and the indicator light will be on. |
Temperature
| Range | Accuracy |
|---|---|
| °C: -40°C ~ 0°C | ±3°C |
| °C: 0°C ~ 1000°C | ±2.0% or ±2°C |
| °F: -40°F ~ 32°F | ±6°F |
| °F: 32°F ~ 1832°F | ±2.0% or ±4°F |
| Resolution: 1°C/1°F | |
| Note: use K-type thermocouple probe | |
6. Maintenance
6.1 Cleaning
When cleaning the meter, please follow these steps:
- Turn off the meter power and remove the probes.
- Wipe the case with a damp cloth or mild detergent. Do not use abrasives or solvents.
- Wipe the contacts in each input socket with a clean swab soaked in alcohol.
⚠ Warning:
Always keep the inside of the meter clean and dry to prevent electric shock or damage to the meter.
6.2 Fuse Replacement
If the fuse is burnt out, the symbol "FUSE" will be displayed when the current gear is selected. It is not allowed to measure current until the fuse is replaced.
⚠ Warning:
After opening the back cover of the meter, do not use the instrument for measurement to prevent electric shock or damage to the instrument.
- Turn off the meter power and remove the probes.
- Remove the screw fixing the back cover and remove the back cover.
- Remove the burnt out fuse, replace it with a new one of the same specification (F10A/250V fuse), and ensure that the fuse is installed in the safety clip and clamped tightly.
- Install the back cover and fix it with screws.
7. Troubleshooting
- No Display/Power On Issue: Check battery installation and ensure batteries are not depleted. Replace batteries if necessary.
- "OL" Indication: This indicates an over-range condition (measurement exceeds the meter's maximum range) or an open circuit. Check your connections and the expected value.
- Inaccurate Readings: Ensure probes are clean and properly connected. Check battery level. If persistent, the meter may require calibration or the probes might be faulty.
- Fuse Blown (Current Measurement): If the meter displays "FUSE" during current measurement, the fuse needs replacement. Refer to section 6.2.
- Auto Power Off Too Soon: The meter has an auto power-off feature after 15 minutes of inactivity. To disable it, press and hold the SEL/💡 key when turning on the meter.
8. User Tips
- Utilize Smart Mode: For general measurements, the Smart (AUTO) mode is highly convenient as it automatically detects the measurement type (voltage, resistance, continuity).
- Check NCV First: Before touching any unknown circuit, use the NCV function to quickly check for the presence of AC voltage, enhancing safety.
- Keep Probes Organized: Always store your test probes neatly to prevent damage and ensure they are ready for use. The included carrying bag is ideal for this.
- Regular Battery Check: Pay attention to the low battery indicator and replace batteries promptly to avoid interruptions during critical measurements.
9. Warranty and Support
For detailed warranty information, technical support, or further assistance, please refer to the official GVDA documentation or contact GVDA customer service. A comprehensive user manual in PDF format is available for download from the manufacturer's website or via the provided link: GVDA GD120B User Manual (PDF).