Posted inInverter Category

Humming sound

Basic checks and reason

  • Humming sound due to incorrect drive in any gate of the mosfet

Luminous LB VX 875 VA

Problem Humming sound and incorrect and variable output voltage
Fault Faulty second mosfet that was found undetected and was not shorted
Solution Check mosfet drive. Found different drives in both mosfet > Checking IC (557 no pnp ic) found OK > checking Zener diode of the mosfet. Found OK >  checking another Zener diode of the mosfet. Found OK >  Checking gate resistance. found OK > Opening all the resistance and closing one by one and then checking the drive voltage . On closing the second resistance the drive voltage dropped that means the second mosfet is faulty. > changed the second mosfet and problem solved. Video.
Parts used Mosfet
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