1. Product Overview
The Pretul SOIN-313MBP is a lightweight, compact, and highly efficient bi-voltage mini inverter welder designed for Shielded Metal Arc Welding (SMAW) processes. It offers a higher duty cycle and lower power consumption compared to conventional welders, making it ideal for various welding tasks.
This welder features a current adjustment knob and a digital display for precise control. It is compatible with both 127 V and 220 V power supplies, providing flexibility for different work environments.

Figure 1: Pretul SOIN-313MBP Mini Inverter Welder with electrode holder cable, ground clamp cable, protective mask, wire brush, and strap.
2. Components Included
The Pretul SOIN-313MBP Mini Inverter Welder package includes the following components:
- 1x Protective Mask
- 1x Wire Brush
- 1x Strap
- 1x Ground Clamp Cable (1.9 m / 6.2 ft, #5 AWG / 16 mm²)
- 1x Electrode Holder Cable (1.8 m / 5.9 ft, #5 AWG / 16 mm²)
- 1x Power Supply Cable with Plug (2 m / 6.5 ft)

Figure 2: Detailed view of the accessories included with the welder.
3. Setup and Connections
Before operating the welder, ensure all connections are secure and the work area is safe and well-ventilated. The welder supports bi-voltage input, automatically adapting to 127 V or 220 V power supplies.
- Power Connection: Connect the power supply cable to a suitable 127 V or 220 V AC outlet. The welder automatically detects the voltage.
- Ground Clamp Connection: Attach the ground clamp cable to the negative (-) terminal of the welder using the quick-change 3/8" borne. Secure the ground clamp to the workpiece or welding table.
- Electrode Holder Connection: Connect the electrode holder cable to the positive (+) terminal of the welder using the quick-change 3/8" borne. Insert the appropriate electrode into the holder.
- Protective Mask: Always wear the protective mask and other personal protective equipment (PPE) before turning on the welder.

Figure 3: Front panel with digital display and current adjustment knob, and rear panel showing the cooling system and power switch.
4. Operating Instructions
The Pretul SOIN-313MBP is designed for SMAW (Shielded Metal Arc Welding) processes. Follow these steps for operation:
- Power On: Flip the power switch located on the rear panel to the 'ON' position. The digital display will illuminate.
- Current Adjustment: Use the yellow knob on the front panel to adjust the welding current. The digital display will show the selected amperage.
- 1 Phase (127 V): Current range 20 A - 100 A
- 2 Phases (220 V): Current range 20 A - 130 A
- Electrode Selection: This welder is suitable for coated electrodes such as 6013, 6011 (up to 5/32" diameter), and 7018 (up to 3/32" diameter). Select the appropriate electrode for your welding task.
- Welding Process: Begin welding, maintaining proper arc length and travel speed. Always ensure good ventilation and wear appropriate safety gear.
- Duty Cycle: The welder has a duty cycle of 6 minutes of work followed by 4 minutes of rest. Adhering to the duty cycle prevents overheating and prolongs the life of the machine.

Figure 4: Key features of the welder, including its suitability for SMAW, portability, and duty cycle information.
5. Maintenance
Regular maintenance ensures the longevity and optimal performance of your Pretul SOIN-313MBP welder.
- Cleaning: Periodically clean the exterior of the welder with a dry cloth. Ensure the cooling vents (located on the rear panel) are free from dust and debris to maintain proper airflow.
- Cable Inspection: Regularly inspect all cables (power, electrode holder, ground clamp) for any signs of damage, fraying, or exposed wires. Replace damaged cables immediately.
- Terminal Check: Ensure the quick-change terminals are clean and free of corrosion. A clean connection ensures efficient current transfer.
- Storage: When not in use, store the welder in a dry, clean environment, away from direct sunlight and extreme temperatures.
6. Troubleshooting
This section provides solutions to common issues you might encounter with your welder. For problems not listed here, contact customer support.
| Problem | Possible Cause | Solution |
|---|---|---|
| Welder does not power on. | No power supply; power switch off; faulty cable. | Check power outlet and cable connection. Ensure power switch is ON. |
| No arc or weak arc. | Poor ground connection; incorrect current setting; damp electrode. | Ensure ground clamp is securely attached. Adjust current. Use dry electrodes. |
| Welder overheats and shuts off. | Exceeded duty cycle; blocked cooling vents. | Allow welder to cool down. Clear any obstructions from cooling vents. Adhere to duty cycle. |
7. Specifications
Detailed technical specifications for the Pretul SOIN-313MBP Mini Inverter Welder:
| Feature | Specification |
|---|---|
| Model Number | SOIN-313MBP (29019) |
| Manufacturer | Truper |
| Color | Yellow |
| Power Source | Electric (AC Powered) |
| Input Voltage (1 Phase) | 127 V AC / 32 A / 50-60 Hz |
| Input Voltage (2 Phases) | 220 V AC / 22 A / 50-60 Hz |
| Current Range (1 Phase) | 20 A - 100 A |
| Current Range (2 Phases) | 20 A - 130 A |
| Maximum Current | 130 A DC |
| Power | 3.5 kVA (1 Phase • 2 Phases) |
| Open Circuit Voltage | 75 V DC (1 Phase) • 62 V DC (2 Phases) |
| Terminals | 3/8" Quick-Change |
| Duty Cycle | 6 minutes work / 4 minutes rest |
| Dimensions (L x W x H) | 26 cm (Depth) x 11 cm (Base) x 17 cm (Height) |
| Weight | 4.32 kg |

Figure 5: Dimensions and key electrical characteristics of the welder.
8. Warranty and Support
For information regarding product warranty, please refer to the warranty card included with your purchase or visit the official Pretul website. For technical support, service, or spare parts, please contact your authorized dealer or the manufacturer's customer service department.
Please retain your proof of purchase for warranty claims.





