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Gate-driver repeat-failure path

Fuji FRENIC G9/G11 Gate-Drive Leakage and Repeat-Failure Path

Maps the search-intent path for repeated Fuji G9/G11 module failures: PWM command, optocoupler/driver output, small capacitor leakage, zener/gate resistor condition, module input capacitance and motor/load evidence.

Functional path

PWM command
Optocoupler / driver stage
Gate resistor and clamp
Small capacitor / bias leakage
IGBT gate-emitter
Motor/load result

Diagnostic signals and checkpoints

Repeated module failureUnbalanced outputWorks for days then failsDriver channel asymmetryModule replacement history

Technician notes

  • A leaky small capacitor can leave static tests almost believable while weakening the channel under real gate-current demand.
  • Do not treat a new module as proof of repair; the driver channel must be able to charge and discharge the IGBT gate cleanly.