1. Press the P+S key in the power-off state first, and hold it together at the same time to turn on the power.

2. Secondly, you can't release the P plus S key before the electronic control start is displayed.

3. Then press the P key to add and subtract the digital menu, select P68 representing the factory protection setting value of 3500 rpm, press the S key to display the data, increase the speed, and return to the P57 menu representing the maximum speed setting, then modify the speed data (preferably no more than 4800 rpm) and then return to the general speed of P 1, and then modify it.

4. Finally, return to the work page, close and save.

1. The needle pitch of the sewing machine is too small. Adjust the needle distance knob of the sewing machine to increase the needle distance of the sewing machine.

2. The feeding teeth of the sewing machine are too low, or the feeding teeth of the sewing machine are seriously worn. Gently lift the feed teeth, adjust the height, and turn the feed teeth to the highest position, so that the feed teeth are exposed from the needle plate by 0.8 mm. If the feed teeth are seriously worn, please replace them with new ones.

3. If the motor speed is slow, check whether the motor pulley is too small. If the pulley is too small, please replace it with a larger pulley. Take a single needle sewing machine as an example. The size of the motor pulley of the sewing machine is 60 ~ 80 mm

4. The belt between the motor pulley and the sewing machine handwheel is too loose, and there is a gap in power transmission. Adjust the belt gap and properly tension the belt.