Symptom: Nothing happens when the device starts up. After observation, the phase loss indicator on the control circuit board is on.

    Cause of failure: The fast fuse is blown. Generally, the fast-blow fuse has a blown indication. It can be judged whether the fuse is burnt out by observing its indication. However, sometimes the fast-fuse is used for too long or the quality is not indicated or the indication is unclear. It needs to be powered off or measured with a multimeter. .

    The treatment method is: replace the fast fuse and analyze the cause of the blow. There are four reasons why a fast fuse is generally blown:

    a. The equipment runs under the conditions of long time, high power and high current, causing the fast fuse to heat up, so that the fuse is hot melted;

    b. The rectified load or the intermediate frequency load is short-circuited, causing instantaneous large current surge, burning the fast fuse and checking its load circuit;

    c. The rectifier control circuit fault causes instantaneous large current surge, and the rectifier circuit should be inspected;

    d. If the contact of the main switch is burnt out or the front-end power supply system has a phase loss fault, measure the line voltage of each stage with the AC voltage of the multimeter to judge the fault position.