Record facts
Recorded diagnostic areaIGBT gate turn-off path
Observed driver reference3120 driver stage
Observed diode markingM5C / replacement observation P5C
Service notes
- An in-circuit reading may conceal an open diode in the turn-off network because adjacent resistors provide a parallel path.
- Gate-drive defects must be resolved before returning a replacement power module to full-power operation.
Related technical records
E019
Current Detection Circuit Fault
Open →POFFThe drive reports E019 during power-up or operation, potentially without a genuine motor overcurrent event.
Input Undervoltage / Drive-Board Supply Indication
Open →CircuitThe keypad displays POFF immediately after power-up or only when the motor is commanded to run.
Emerson TD900 IGBT Turn-Off Drive Stage
Open →WorkflowA documented TD900 gate-drive observation shows a 3120 driver arrangement using a diode/resistor/capacitor network to improve IGBT turn-off charge removal where no negative gate supply is used.
Emerson TD900 E019 Current-Detection Investigation
Open →The TD900 presents E019 or a suspected false current indication.
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