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.
Evidence intake
Turn this record into a qualified service request
A repair decision is much more reliable when the request includes the exact identity of the drive, the first fault evidence and the machine condition when the symptom appeared.
- Complete drive type code / MLFB or nameplate model
- Fault code, fault value and first event before reset
- When the event appears: power-up, enable, ramp, run, decel or stop
- Motor/cable connected or isolated during the symptom
- Visible board, option-card, module and connector identifiers
- Previous repair history, replacement parts and repeat-failure pattern