GVDA GD188 Digital Oscilloscope Multimeter User Manual

1. Introduction

Thank you for choosing the GVDA GD188 Digital Oscilloscope Multimeter. This innovative 3-in-1 device combines the functions of a digital storage oscilloscope, a 6000-count digital multimeter, and a signal generator, offering great convenience for field testing and various electrical measurements. Please read this manual carefully before use, paying special attention to the safety instructions, and keep it in a safe place for future reference.

Key Features:

• 50Msps high-speed sampling chip with 12MHz analog bandwidth.
• 6000 counts digital multimeter for precise measurements.
• One-key access to voltage waveform display with automatic, conventional, and single scanning modes.
• Integrated signal source output for sine, triangle, and square waveforms with adjustable parameters (frequency, duty cycle, amplitude).
• Configured with replaceable 18650 lithium batteries for environmental friendliness.
• Data and waveform storage function: 100 records for DMM data and 10 records for OSC waveforms.
• Waveform range up to 200V/grid, with a maximum measurement of 1600Vpp.
• Relative value measurement to eliminate lead resistance, distributed capacitance, or interference signals.
• Comprehensive multimeter functions: voltage, current, resistance, capacitance, frequency, duty cycle, diode, and continuity testing.
• Automatic/manual range switching with real-time and stored data display on the same screen.
• Overload protection with 750mA and 10A double fuses for enhanced safety.
• 15-minute auto-sleep function when no operation is detected.
• 2.4-inch HD color screen for clear display.
• Panel calibration with memory calibration factor, eliminating potentiometer adjustment for higher reliability.

2. Safety Instructions

The technical design of this digital storage visual wave multimeter complies with IEC1010-1 safety specifications, overvoltage measurement category II CAT II - 1000V, and pollution protection level 1. Adherence to these safety guidelines is crucial for preventing instrumentation damage and personal injury.

General Safety Precautions:

• Inspect Before Use: Always check the meter's case for damage, cracks, or missing plastic parts. Ensure the meter probes and connecting wire insulation are intact. Do not use if damaged.
• Probe Handling: Keep fingers away from the metal part of the meter pen probe when in use.
• Environmental Conditions: Do not operate in hot, humid, rainy, or flammable environments, or when the instrument is wet.
• Voltage/Current Limits: Never apply voltage/current exceeding the maximum limits specified in the table below.
• Function Switching: Always disengage the pen probe from the test point before changing the measuring gear, unplugging the pen, or switching the machine on/off.
• Voltage Measurement: Do not perform voltage measurements when the voltage to ground on the reference input "COM" exceeds 500 V.
• Current Measurement: Do not perform current measurements on circuits with voltages above 250V.
• Impedance/Continuity Tests: When performing current, resistance, on/off test, diode, or capacitance measurements, never connect the meter pen across both ends of a voltage source.
• Capacitor Discharge: Before conducting resistance, diode, or on/off tests, ensure the equipment under test is powered off and any capacitors in the power circuit are fully discharged.
• Fuse/Battery Replacement: Before opening the back cover to replace the fuse or battery, power off the instrument and remove the meter probes from the circuit under test. Use only fuses of the same specifications.
• Unauthorized Modification: Do not modify, disassemble, or use the product or accessories for purposes other than their intended functional design. Do not substitute accessories.
• Child Safety: Do not allow children to use this equipment or treat it as a toy.

Safety Signs:

Measurement Function Maximum Limits:

3. Setup

Power On and Off:

To power on the device, rotate the functional range knob to any measurement position. To power off, rotate the knob to the "OFF" position.

• Attention: Always ensure the test meter probes are disconnected from any test points before turning off the power.
• Attention: When finished using the instrument, always turn off the power.

Auto-Sleep Function:

The meter will automatically enter sleep mode if there is no key or knob operation within a set period. To disable the auto-sleep function and set it to continuous running, hold down the "F1" key while rotating the knob to power on the device.

Initial Setup:

Upon first use or after a long period of inactivity, ensure the device is adequately charged. The screen will display a red "battery" prompt when charging is needed. Use a Type-C charger (DC5V, current ≥ 1A). The charging indicator light will be red during charging and blue when fully charged.

4. Operating Instructions

4.1. Oscilloscope Operation

The oscilloscope function allows for waveform visualization and analysis.

Entering/Exiting Oscilloscope Mode:

From the multimeter (DMM) voltage section, long press the "AUTO" button for 2 seconds to enter Oscilloscope (OSC) mode. To exit OSC mode and return to DMM mode, long press "AUTO" again for 2 seconds.

Amplitude Ranges:

• mV Filegear: Amplitude range 50mV/div ~ 200mV/div, measurable amplitude 0 ~ 1.6Vpp.
• V-range OSC Mode: Amplitude range 500mV/div ~ 200V/div, measurable amplitude 0 ~ 1600Vpp.

Basic Display in Oscilloscope Mode:

Function Keys (F1-F4) and Main Menu:

The multi-functional keys F1-F4, located at the bottom of the LCD screen, change their function based on the current range and operating mode. The on-screen menu prompts guide operation.

Time Base Adjustment:

In the oscilloscope main menu, press F1 (TIME) to enter the time base adjustment sub-menu.

• Press F1 (EXIT) to return to the main menu.
• Press F2 (◄) and F3 (►) to adjust the time base (t/div).

Range Adjustment:

In the oscilloscope main menu, press F2 (VOLT) to enter the range adjustment sub-menu.

• Press F1 (EXIT) to return to the main menu.
• Press F2 (▲) and F3 (▼) to adjust the vertical range (V/div).

Trigger Control:

In the oscilloscope main menu, press F3 (TRIG) to enter the trigger control sub-menu.

• Press F1 (EXIT) to return to the main menu.
• Press F2 (rising edge / falling edge symbol) to select rising or falling edge trigger.
• Press F3 (MODE) to select the trigger mode.
• Press F4 (LEVEL) to enter the Trigger Level Adjustment sub-menu.

Trigger Level Adjustment:

In the trigger setting sub-menu, press F4 (LEVEL) to enter the trigger level adjustment sub-menu.

• Press F1 (EXIT) to return to the Trigger Control sub-menu.
• Press F2 (▲) and F3 (▼) to decrease or increase the trigger level. The display will mark the corresponding position.
• Press F4 (RESET) to reset the trigger level to zero.

Trigger Modes:

• Auto: Acquires waveforms even without a trigger condition. If no trigger, it triggers itself after a period. Waveform scrolls if not synchronized. Useful for irregular signals or DC power waveforms.
• Normal: Acquires waveform data only after a trigger signal is detected. No new waveform is acquired if no trigger occurs.
• Single: Acquires waveform data once a trigger condition is detected. The latest waveform is automatically held.

Prompt Messages for Scan Status:

• Auto: Waveforms acquired without trigger conditions.
• Wait: Waiting for the trigger condition.
• Trig: Trigger condition has been detected.
• Stop: Keep Locked.

Holding Signal Waveforms:

To hold the current waveform for closer inspection, press the "SAVE" key. This stops data acquisition and keeps the displayed content. Press "SAVE" again to resume normal operation.

Storage and Readout of Signal Waveforms:

The instrument can store up to 10 OSC waveform data records.

1. Press "SAVE" to hold the current waveform.
2. Long press "SAVE" for 2 seconds to enter the database.
3. Use F1 (◄) / F2 (►) to select a save location.
4. Press F4 (SAVE) to save the currently held waveform to the selected location.
5. Press F3 (ERASE) to delete the waveform at the current page position.
6. Long press "SAVE" for 2 seconds to exit the database.

4.2. Multimeter Operation

The multimeter function provides various electrical measurements.

Entering Multimeter Mode:

The device defaults to multimeter (DMM) mode upon power-on. You can also long press the "AUTO" key to switch to DMM mode from oscilloscope mode.

• Warning: When changing the measurement function, always detach the meter probes from the test point first.

Basic Display in Multimeter Mode:

Switching Measurement Functions:

Rotate the knob to select the desired test function. Press the F3 (SEL) key to cycle through sub-functions within a gear (e.g., DC/AC voltage, Diode/Continuity).

Manual/Automatic Range Selection:

The meter starts in auto-range mode. To switch to manual range, press F4 (RNG). Each subsequent press of F4 (RNG) cycles through available ranges. Press the AUTO key to return to auto-range mode.

Relative Value Measurement Mode:

Press F1 (REL) to store the currently displayed measured value as a reference and activate relative value mode. The screen will then show the difference between the current measurement and the stored reference. Press F1 (REL) again to exit. This mode automatically switches to manual range control.

Peak Hold (P-H) Mode:

Press F2 (P-H) to activate peak hold mode, which displays the maximum and minimum measured values. These values update with each new measurement. The LCD will show MAX and MIN peak values.

• F1 (EXIT): Exit peak hold mode.
• F2 (RUN): Start peak hold measurement.
• F3 (STOP): Stop refreshing peak measurement (current max/min values will not change).
• F4 (REST): Reset measured peak to start a new measurement.

AC and DC Voltage Measurement:

1. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
2. Rotate the knob to the "V" or "mV" function. "VOLTAGE" will appear on screen.
3. Press F3 (SEL) to switch between DC/AC/Hz/% measurement methods (Hz/% is not available in mV filegear).
4. Touch the test points with the meter probes and read the displayed voltage.

• Tips: If measured voltage exceeds 24V, a red "⚡" warning, 3 beeps, and flashing red light indicate safety concern.
• Warning: Do not apply 700V AC or 1000V DC for more than 10 seconds to avoid damage.

AC and DC Current Measurement:

1. Insert the black test lead into the "COM" socket and the red test lead into the "mA" or "10A" socket.
2. Rotate the knob to the "A", "mA", or "μA" function. "CURRENT" will appear on screen.
3. Press F3 (SEL) to switch between DC and AC measurement methods.
4. Insert the meter probes in series with the circuit under test and read the displayed current.

• Warning: Do not perform current measurements on circuits with voltages above 250V.
• Warning: When using the 10A range, measurement time should not exceed 30 seconds within any 15-minute period to prevent damage.

Frequency and Duty Cycle Measurement:

1. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
2. Rotate the knob to the "Hz%" gear.
3. Press F3 (SEL) to select between frequency and duty cycle functions.

Resistance Measurement:

1. Warning: Disconnect power and discharge capacitors before measuring resistance.
2. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
3. Rotate the knob to the "Ω" function. "RESISTANCE" will appear on screen.
4. Connect probes across the circuit or component. For accuracy, disconnect the component from the circuit.
5. Read the displayed resistance value.

Diode Detection:

1. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
2. Rotate the knob to the "Ω" function.
3. Press F3 (SEL) to select the diode detection function. "DIODE" will appear on screen.
4. Place probes across the diode or semiconductor PN junction. (Silicon tube: ~0.5-0.7V; Germanium tube: ~0.15-0.25V).

Continuity Test (On/Off Test):

1. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
2. Rotate the knob to the "Ω" function.
3. Press F3 (SEL) to select the on-off test function. "CONTINUITY" will appear on screen.
4. Contact the circuit under test with probes. A buzzer will sound if resistance is less than 50Ω.

• Warning: Do not test diodes or circuits containing voltage.

Capacitance Measurement:

1. Warning: Disconnect power and discharge capacitors before measuring capacitance.
2. Insert the black test lead into the "COM" socket and the red test lead into the "VOCx" socket.
3. Rotate the knob to the "Cx" function. "CAPACITANCE" will appear on screen.
4. Touch the capacitor under test with probes and read the displayed capacity.

4.3. Signal Source Operation

The signal source function allows generating various waveforms for testing.

Generating Signals:

1. Insert the black test lead into the "COM" socket and the red test lead into the "mA" socket.
2. Rotate the knob to the "V" measurement function.
3. Long press the "light bulb" key for 2 seconds to enter/exit the signal setting interface.

Signal Source Parameters:

• F1 (WAVE): Select waveform type (Sine, Triangle, Square).
• F2 (FREQ): Adjust frequency.
• F3 (DUTY): Adjust duty cycle (available only for square waveform).
• F4 (VOLT): Adjust amplitude.
• AUTO key: Turn the signal output on or off.

Night Mode Switch:

Short press the "light bulb" key to switch night mode on/off. Night mode turns off the LED light effect.

5. Specifications

5.1. General Features:

5.2. Oscilloscope Features:

5.3. Signal Source Features:

5.4. Multimeter Features:

5.5. Display Symbols and Icons:

6. Maintenance

Keep Dry:

If the meter gets wet, dry it immediately and do not use it until completely dry to prevent damage.

Use and Storage at Room Temperature:

Avoid extreme ambient temperatures, as they can shorten the life of electronic components, deform plastic parts, and render the meter unusable.

Handle Carefully:

Drops or impacts can damage the LCD screen, internal electronic components, or the casing.

Keep Clean:

Regularly wipe the instrument's housing with a damp cloth moistened with a small amount of mild detergent. Do not use abrasive materials, chemical solvents, or alcohol.

Replacement of Fuse:

1. Remove the probes from the test point and turn off the power.
2. Loosen the set screw, remove the back cover. The fuse is located on the back of the test socket.
3. Remove the blown fuse and replace it with a new fuse of the same specification: 750mA/250V for 600mA circuits, and 10A/250V for 10A circuits.
4. Install the back cover and secure it with screws.

Repair of Instruments:

This product is a precision instrument. Unauthorized modification of wiring, replacement of components, or calibration and repair work without authorization from our Product Service Center is not permitted.

7. Troubleshooting

If your instrument malfunctions, you may perform the following checks before seeking repair:

No Screen Display, No Key Response:

• Check if there is power. Charge the machine if the battery is low.
• Turn the knob to the OFF position and then back to a measurement position.

Unable to Measure:

• Check the condition of the meter probes. Short-circuit the probes in the on/off gear to test their continuity.

Current Cannot Be Measured:

• The fuse may be melted. Replace the fuse as described in the Maintenance section.

• Warning: Always disconnect the probes from any voltage source before opening the battery back cover. Do not use the meter until the back cover is securely closed.

8. User Tips

• Battery Management: Always check the battery level before starting critical measurements, especially for prolonged oscilloscope use, to ensure uninterrupted operation.
• Auto-Ranging vs. Manual: While auto-ranging is convenient for quick checks, consider switching to manual range for more precise or stable readings in specific applications.
• Data Storage: Make use of the waveform and DMM data storage functions to record important measurements for later analysis or documentation.
• Signal Source Output: When using the signal generator, double-check the selected waveform type, frequency, duty cycle, and amplitude to match your testing requirements.
• Safety First: Always prioritize safety. Before any test, especially involving resistance or capacitance, ensure the circuit is de-energized and capacitors are discharged.

9. Warranty and Support

The content of this manual is subject to change without notice. For warranty claims or technical support, please contact your seller or the manufacturer directly. Please note that the manufacturer does not assume responsibility for man-made damage, unauthorized dismantling, revision, upgrade, or improper use of the product.

For further assistance, you may refer to the official user manual (PDF) available at: User manual (PDF)