1. Introduction
This manual provides essential instructions for the safe and effective use of your onerbl AC-DC Adapter, designed as a replacement power supply for the FITINDEX FT-YB-02 Li-ion Battery Vibrating Yoga Massage Muscle Electric Foam Roller. Please read this manual thoroughly before use and retain it for future reference.
2. Safety Information
To prevent injury or damage to the adapter or connected device, observe the following safety precautions:
- Do not expose the adapter to water, moisture, or extreme temperatures.
- Do not disassemble or modify the adapter.
- Ensure the adapter is used with devices that match its voltage and amperage specifications.
- Avoid placing heavy objects on the power cord.
- Unplug the adapter from the power outlet when not in use for extended periods.
- Keep out of reach of children.
3. Product Overview
The onerbl AC-DC Adapter is a compact power supply designed to convert alternating current (AC) from a wall outlet to direct current (DC) required by compatible devices, such as the FITINDEX FT-YB-02 foam roller.

Figure 1: The onerbl AC-DC Adapter, showing the main unit with a two-prong US plug and the attached DC barrel connector cable.

Figure 2: Front and side profiles of the adapter, highlighting its compact design and the input specifications printed on the casing.

Figure 3: Diagram illustrating the physical dimensions of the adapter unit (approximately 2.6 x 1.6 x 1.2 inches) and the cable length (76 inches).
4. Setup
- Verify Compatibility: Ensure your device, such as the FITINDEX FT-YB-02 foam roller, requires a 9V DC power input with a 1A current rating and has a compatible DC barrel connector.
- Connect to Device: Insert the DC barrel connector of the adapter firmly into the power input port of your device.
- Connect to Power Outlet: Plug the AC prongs of the adapter into a standard electrical wall outlet (100-240V AC, 50/60Hz).

Figure 4: The AC-DC adapter connected to a power strip, demonstrating a typical setup for charging or powering a device.
5. Operating Instructions
Once properly connected, the adapter will supply power to your device. If your device has a charging indicator, observe it to confirm that charging has begun. The adapter is designed for continuous operation within its specified limits.
- The adapter features Over Voltage Protection and Over Heat Protection to safeguard both the adapter and your connected device.
- It supports a Worldwide AC Input range of 100-240V, 50/60Hz, making it suitable for international use with appropriate plug adapters (not included).
6. Maintenance
The onerbl AC-DC Adapter requires minimal maintenance:
- Keep the adapter clean and free from dust. Use a dry, soft cloth for cleaning.
- Store the adapter in a cool, dry place when not in use.
- Regularly inspect the cable and connectors for any signs of damage. If damage is found, discontinue use immediately.
7. Troubleshooting
If the adapter is not functioning as expected, consider the following:
- No Power to Device:
- Ensure the adapter is securely plugged into both the wall outlet and the device.
- Check if the wall outlet is functional by plugging in another device.
- Verify that the device itself is operational and not experiencing other issues.
- Adapter Overheating:
- Unplug the adapter immediately.
- Ensure there is adequate ventilation around the adapter. Do not cover it.
- Confirm that the connected device's power requirements do not exceed the adapter's output capacity.
- Loose Connection:
- Gently re-seat the DC connector into the device's port.
- Inspect the DC connector for any physical damage or bent pins.
If issues persist, discontinue use and contact the seller or manufacturer for assistance.
8. Specifications
| Brand | onerbl |
| Model Number | FT-YB-02 |
| Input Voltage | AC 100-240V, 50/60Hz |
| Output Voltage | DC 9V |
| Amperage | 1A |
| Power Output | 9W |
| Connector Type | AC (US 2-prong), DC (Barrel) |
| Cable Length | 76 inches (approx. 1.93 meters) |
| Features | Over Voltage Protection, Over Heat Protection |
9. Warranty and Support
For warranty information and customer support, please refer to the documentation provided with your purchase or contact the seller directly. The manufacturer of this product is Shenzhen Waweis Technology Co., Ltd.





