1. Operation selector in the wrong position.
2. Demagnetized machine.
3. Reduced speed.
4. Faulty rotating diodes.
5. Failure in the windings.

1. Move the selector.
2. Apply to the terminal a DC voltage of between 6-12 V for a second.
3. Check the speed and bring it to the rated value.
4. Check and replace.
5. Check the windings resistances as per the table.

No-load voltage too low

Low welding current

1. Current selector in the wrong position.
2. Cable jack in the wrong range.
3. Speed too low.
4. Wrong capacitor value.
5. Faulty rotating diodes.

1. Move the selector.
2. Move the jack.
3. Check and regulate speed.
4. Check and replace.
5. Check the resistance as per the table.

No-load voltage too high

High welding current

1. Current selector in the wrong position.
2. Cable jack in the wrong range.
3. Excessive motor speed.
4. Wrong capacitor value.
5. Faulty rotor.

1. Move the selector.
2. Move the jack.
3. Regulate the motor speed.
4. Check and replace.
5. Change the rotor.

1. Probable overload.
2. The engine speed slows down.
3. Faulty rectifier bridge.

1. Check the load current.
2. Check engine dimensions.
3. Check and replace.

1. Fault in impedance.

1. Check the resistance according to table and replace.

Unstable voltage

Unstable welding current

1. Loose connections.
2. Irregular rotation.

1. Check the connections.
2. Verify the rotation uniformity.

1. Partially obstructed ventilation openings.
2. Probable overload.

1. Remove and clean the air inlet and outlet grids.
2. Check the load current.

1. Faulty bearings.
2. Faulty coupling.

1. Check and replace.
2. Verify and repair.