1. Introduction
Thank you for choosing the POSEIDON HM138 Wireless Tattoo Pen. This professional-grade electric tattoo gun is designed for precision and comfort, featuring a powerful custom motor, quiet stability, and a comfortable, anti-slip design. It offers adjustable voltage, a strong start mode, and is compatible with most needle types available on the market. This manual provides essential information for the safe and effective use of your new tattoo machine.
Product demonstration video showing unboxing, needle insertion, and basic operation of the POSEIDON HM138 Wireless Tattoo Pen.
2. Safety Information
- This appliance can be used by children aged from 8 years and above and persons with reduced physical, sensory or mental capabilities or lack of experience and knowledge if they have been given supervision or instruction concerning use of the appliance in a safe way and understand the hazards involved.
- Children shall not play with the appliance.
- Cleaning and user maintenance shall not be made by children without supervision.
- The appliance must only be supplied at safety extra-low voltage corresponding to the marking on it.
- WARNING: To avoid danger of suffocation, keep this plastic bag away from babies and children. Do not use this bag in cribs, beds, carriages or play pens. This bag is not a toy.
3. Package Contents
The POSEIDON HM138 Wireless Tattoo Pen package typically includes:
- POSEIDON HM138 Wireless Tattoo Pen
- USB Type-C Charging Cable
- Instruction Manual
- Additional accessories (e.g., sample inks, needle cartridges, grip tape) may vary by kit.
4. Product Overview
The POSEIDON HM138 is a compact and powerful wireless tattoo pen. Its design prioritizes user comfort and operational efficiency.

POSEIDON HM138 Wireless Tattoo Pen with digital display showing 4.0V.
4.1 Key Features
- Quiet Stability: Equipped with a strong movement motor for stable needle operation.
- Ergonomic Design: New hand-slip anti-slip design ensures a comfortable grip, reducing fatigue during long sessions.
- Durable Construction: Exquisite workmanship, high hardness, lightweight, and unibody design.
- Enhanced Needle Interface: Features an aluminum alloy protective layer at the needle cylinder interface for tight combination and wear resistance.
- Versatile Use: Suitable for embroidery tattooing.
4.2 Controls and Display

Detailed view of the tattoo pen's digital display and controls.
The tattoo pen features an intuitive digital display and control buttons:
- A: Type-C Charging Port
- B: Supply Voltage Display
- C: On-Off Switch / Power Button
- D: Voltage Reduction Key (-)
- E: Function Keys (M)
- F: Duration of Use (Timer)
- G: Voltage Increase Key (+)
- H: Hub Movement Indicator
5. Setup
5.1 Initial Charging
Before first use, fully charge the tattoo pen using the provided USB Type-C cable. The display will show a charging symbol. A full charge typically takes 2-3 hours.
5.2 Needle Cartridge Installation
- Ensure the machine is turned off.
- Carefully insert the desired needle cartridge into the front end of the tattoo pen. Twist gently to secure it in place.
- Adjust the needle protrusion by rotating the grip of the pen.

The tattoo pen is compatible with most needle types available on the market.
6. Operation
6.1 Power On/Off
- To Turn On/Off: Press and hold the power button (C) for 1.5 seconds.
- To Start Motor and Begin Timing: After turning on, press and hold the power button (C).
- To Pause: Press the power button (C) once during operation.
- To Resume: Press the power button (C) once again.
- To Turn Off from Paused State: Press and hold the power button (C) for 1.5 seconds.
6.2 Voltage Adjustment
- Use the Voltage Increase Key (+) (G) and Voltage Reduction Key (-) (D) to adjust the voltage. Each press changes the voltage by +/- 0.1V.
- Hold the '+' or '-' button for continuous voltage adjustment.
- The voltage range is 4.0V to 12.0V. The default voltage is 8.0V.
6.3 Strong Start Mode
- To activate: Double-click the power button (C). The "strong start" symbol will appear on the display.
- Function: The machine will operate at its highest speed for 0.5 seconds, then automatically return to the previously set voltage.
6.4 Memory Function
The machine remembers the last active voltage setting or gear and will resume with these settings upon the next power-on.
6.5 Display Management
- The display automatically turns off after 10 seconds of inactivity.
- The machine enters sleep mode after 5 minutes of inactivity.
6.6 Automatic Needle Operation (Threading/Unthreading)
If needle operation (threading) is not performed again within 5 minutes, automatic threading and unthreading will occur. During strong start mode, the previously set needle length will be maintained for 0.5 seconds before returning to the set length.
6.7 Function Keys (Needle Length/Frequency Adjustment)
- Press the function button (E) to cycle through available options.
- Use the '+' (G) and '-' (D) buttons to adjust settings such as needle length or frequency.
- The setting can also be changed by rotating the function button.
- Press the power button (C) to exit the setting mode.
- Hold the function button (E) for 5 seconds for automatic setup.
6.8 Clamping Mode
- Press the function button (E) to switch between clamping mode and normal mode.
- In clamping mode, use the '+' (G) and '-' (D) buttons to adjust the clamping frequency.
- A setting like "20NPS10HZ" is applicable for maneuvering the function button.
- Hold the function button (E) for 5 seconds for automatic setup.
7. Maintenance
Proper maintenance ensures the longevity and optimal performance of your tattoo pen.
- Cleaning: Always clean the machine thoroughly after each use. Use appropriate sterilization solutions and follow industry standards for hygiene.
- Storage: Store the tattoo pen in a clean, dry place away from direct sunlight and extreme temperatures.
- Charging: Use only the provided Type-C cable for charging. Ensure the power source current is below 2A.
- Avoid Disassembly: Do not attempt to disassemble the internal components of the machine, as this may void the warranty and cause damage.
8. Troubleshooting
The machine is equipped with error indicators to help diagnose common issues:
- E1 Error: This code is displayed if the motor lock or overload protection is activated. If the motor is restarted without resolving the underlying issue, E1 will reappear.
- E2 Error: This code indicates that overcurrent protection has been activated.
If you encounter persistent issues not covered here, please refer to the additional resources or contact customer support.
9. Specifications
| Feature | Detail |
|---|---|
| Model | HM138 |
| Type | Electric Tattoo Gun |
| Frame Material | Aerospace-grade Aluminum Alloy |
| Technology | Five-axis precision CNC machining |
| Motor | Japanese Motor, 8V/8000 U/min |
| Principle | Direct-drive long-axis |
| Hub | 4.0 mm |
| Needle Length Adjustment | 1 mm - 4.2 mm |
| Working Voltage | 4-12V |
| Grip Distance | 42 mm |
| Battery Capacity | 1500 mAh (2300 mA mentioned in OCR, using 1500mAh from image for consistency) |
| Battery Life | 7 hours (from image) / 4-6 hours (from OCR) - Using 4-6 hours as a more conservative estimate. |
| Charge Time | 2 - 3 hours |
| Batteries Included | Yes |
| Commodity Quality Certification | CE |
| Origin | Mainland China |

Key specifications of the POSEIDON HM138 Tattoo Pen.
10. User Tips
No specific user tips were available from provided reviews or Q&A content.
11. Additional Resources
For a detailed user manual in PDF format, please refer to the following document: