Light touch switch and button switch according to the on off position of mechanical properties can be divided into the compound switch, since the compound switch, lock switch. When light touch switch and button switch power supply malfunction about what to do, we teach everyone engineering maintenance under the light touch switch and button switch power supply method is as follows:
A touch, testing rectifier circuit switches and button switches D1D4 breakdown or open circuit, filter circuit of capacitance is damaged, balancing resistor R1, R2 is normal, step-down resistance R3 will burn out or resistance increase failure power (test);
Second, the test for a normal absorption loop D5, R11, C9 power (test);
Three, in determining the components of normal cases, we can put the light touch switch and button down from the inverter switch power board separately carries on the electrical test. Slowly with pressure regulator to switch power supply of rated voltage value, at this time should be able to hear when transformer vibration squeak, such as didn't hear the sound of the start up, using a multimeter to test whether UC3844 power level between positive and negative about 12 v16v dc voltage;
Four, detection of the secondary output winding rectifier filter element, see whether filter capacitance bulge, or is damaged, to rule out the possibility of secondary circuit short circuit;
Five, after determining UC3844 voltage of the power supply is normal, can use the oscilloscope check UC3844 6 feet for the PWM wave output to light touch switch and button switch tube end to trigger (according to different circuit design, the frequency of PWM wave between 20 khz100khz);
Six, if not the PWM wave output, change the time element C5, R8, C6 or UC3844. After the above steps, light touch switch and button switch power supply should be able to work normally. In frequency converter, many different kinds of switching power supply, but the basic principles are the same, such as management of each PWM chip has the supply, timing components RC network, output PWM wave port and so on, as long as we understand the working principle of them, according to certain procedures to be able to take out most of the fault.