FNIRSI-138 Pro Digital Oscilloscope User Manual

Product Overview

The FNIRSI-138PRO is a highly practical and cost-effective handheld digital oscilloscope designed for the maintenance industry and R&D education sectors. It features a real-time sampling rate of 2.5MS/s and a bandwidth of 200KHz. The device supports touch input and offers various trigger functions (single, normal, automatic) for analyzing periodic and aperiodic signals. It can measure voltages up to ±400V and displays waveforms on a 2.4-inch high-definition LCD screen with a resolution of 320*240. The oscilloscope is powered by a built-in 1000mAh lithium battery, providing approximately 4 hours of continuous use on a full charge.

Product Introduction

The FNIRSI-138 Pro Digital Oscilloscope is a versatile tool for electronic testing and analysis. Its key features include:

• Real-time sampling rate: 2.5MS/s
• Bandwidth: 200KHz
• Touchscreen interface
• Trigger modes: Single, Normal, Automatic
• Voltage measurement range: up to ±400V
• Display: 2.4-inch LCD (320*240 resolution)
• Battery: 1000mAh lithium battery (approx. 4 hours runtime)
• One-key AUTO function for automatic waveform display

Panel and Button Introduction

The FNIRSI-138 Pro has the following interfaces and buttons:

• 1. BNC probe interface: For connecting external probes.
• 2. RST reset switch: Used for resetting the device.
• 3. Type-C interface: For charging and firmware upgrades.
• 4. ON/OFF switch: Powers the device on or off.
• 5. Function buttons: Used for various operations and navigation.

The front panel features a display showing waveform data, including:

• Vmax: Maximum voltage
• Vmin: Minimum voltage
• Vave: Average voltage
• Vrms: Root Mean Square voltage
• Vpp: Peak-to-peak voltage
• Fre: Frequency
• Dut: Duty cycle
• Cyc: Cycle time
• Vertical Sensitivity: Voltage per division (e.g., 1V/Div)
• Time Base: Time per division (e.g., 200us/Div)
• Coupling Mode: AC or DC coupling
• Run/Stop Status: Indicates if the waveform is running or paused.

Icon Indication

The display includes several indicator icons:

• Trigger edge indicator icon: Shows the trigger edge (rising or falling).
• Trigger mode indicator icon: Displays the current trigger mode (Auto, Single, Normal).
• Baseline indication icon: Indicates the 0V voltage level.
• Trigger voltage indicator icon: Shows the trigger voltage level.
• 1X/10X mode indicator icon: Reflects the probe's attenuation setting.
• Input coupling mode indication icon: Shows AC or DC coupling.
• Running pause indication icon: Indicates RUN (running) or STOP (paused) status.

Parameter Index

Button Operations

*No key operation for 0.5 seconds, parameters will be automatically saved.

Firmware Upgrade

1. Press the “OK” button to power on and enter the U disk upgrade mode.
2. Connect the Type-C port on the board to the computer using the Type-C cable. A U disk named “FNIRSI-138 Pro” will appear on the computer.
3. Copy the firmware file to the U disk. The firmware upgrade is then complete.

Note: Firmware upgrade is only supported on WIN10 computer systems.

Analysis Of Common Problems

1. Why can't the machine be turned on after receiving it?

The product may consume some power during testing before shipment and during storage/transportation, potentially leading to a depleted battery upon receipt. Charge the device using a 4-9V charger before use. Avoid charging via computer USB as it may provide insufficient power.

2. How to tell if the battery is fully charged?

The charging indicator light will change from red to green when the battery is fully charged.

3. Why can't I see a waveform, only multiple lines jumping up and down?

Ensure the trigger mode is set to “Auto” and press the [AUTO] key. If the issue persists, check if the probe is properly grounded or if the probe clip is open-circuited. Use a multimeter to test the probe's functionality.

4. Why does the tested waveform keep shaking left and right and cannot be fixed?

Adjust the trigger voltage using the up and down keys. Position the yellow trigger pointer between the upper and lower parts of the waveform to stabilize it.

5. Why is there no waveform when measuring a battery or other DC voltage?

A stable DC signal does not produce a waveform. When using DC coupling, an offset line may appear due to vertical sensitivity adjustments. No waveform will be displayed in AC coupling mode regardless of adjustments.

6. Why is the VPP peak-to-peak data below 600V+, not 220V or 310V, when measuring the 220V mains waveform?

Mains 220V is an AC signal with a positive peak of +310V and a negative peak of -310V, resulting in a VPP of approximately 620V. The effective voltage (RMS) is 220V, which can fluctuate between 180-260V, leading to a VPP range of 507-733V.

7. Why is the measured mains 220V waveform not a standard sine wave and shows distortion?

Mains power grids often contain harmonic components that can distort the sine wave, resulting in a non-ideal waveform. This is a normal phenomenon and usually not an issue with the oscilloscope itself.

8. Why are the baseline (0V) and the left arrow (OV indicated) on the screen different in position when there is no signal input, and there is a relatively large offset?

To resolve this, unplug the probe and USB cable, press the [AUTO] key to enter the calibration confirmation interface, and then press [OK] to initiate automatic calibration.

Notes

• Ensure the oscilloscope's gear setting matches the probe's attenuation setting.
• Avoid touching any metal parts of the oscilloscope when measuring high voltages to prevent electric shock.
• Do not perform high voltage tests while the device is charging.
• When calibrating, unplug the BNC probe or short-circuit its positive and negative poles.
• Firmware upgrades are supported only on WIN10 and above. Do not copy files other than firmware to the upgrade disk, as this may cause irreversible damage.
• Use the voltage within the specified range for charging.

Production Information

• Product Name: Digital Oscilloscope
• Brand/Model: FNIRSI/FNIRSI-138 Pro
• Service Tel: 755-83242477
• E-mail: 455773262@qq.com
• Manufacturer: Shenzhen FNIRSI Technology Co., Ltd.
• Address: 8th Floor, West of Building C, Weihuada Industrial Park, Dalang Street, Longhua District, Shenzhen, Guangdong Province
• Website: www.fnirsi.cn

Documents / Resources

• FNIRSI FNIRSI-138 Pro Digital Oscilloscope [pdf] User Manual
• FNIRSI FNIRSI-138 Pro Digital Oscilloscope [pdf] User Manual

References

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