That night, he added a new line to the maintenance log: H66 – Cause: water ingress at encoder connector pin 4. Cleaned. No parts replaced. Downtime: 12 minutes.
The most frequent culprit for H66 is the physical wiring between the motor and the drive.
The option card or the drive’s internal control board may be damaged. ✅ Troubleshooting Steps
While most H66 cases are resolved by reseating the card or updating firmware, contact Yaskawa (1-800-927-5292 in US) if:
Sometimes the fault is genuine. The motor is actually getting too hot.
: The most frequent cause is a poorly seated or loose cable between the drive and the digital operator (keypad) or communication option card. EMI/Electrical Noise