I recently repaired a Fuji Electric Servo-Drive, Model RYG.50HA-RP. The servo-drive would not power up when the 220VAC, 3-phase line voltage was supplied. No LED's would illuminate on the front panel.
I dissassembled the servo-drive and found that a very small switching transformer on the IGBT FIRING PCB had scorched wires that had burnt through the yellow insulation tape. The transformer was about the size of a dime. This transformer was used to make the isolated power supplies for the three high side and the three common low side firing channels for the motor's IGBT POWER MODULE. Written on the transformer was a part number 66300V. But upon research, we found that the part was not available for sale, nor was it currently manufactured.
Our Lead Engineer, Ron Abts, unwound one winding of the transformer to determine the diameter of the wire and the number of windings and direction of turn. I then removed the other bad windings, also noting the number of windings and direction of turn. In all, there were three bad windings that had to be replaced.
I rewound the three bad windings and soldered the transformer to the IGBT FIRING PCB. I then removed the IGBT POWER MODULE, so that I wouldn't destroy it if the transformer wasn't wound correctly. I applied 220VAC, 3-phase to the line input of the servo-drive and the LED's on the front panel illuminated. I checked the control voltages, the 300VDC Bus Voltage, and the IGBT Isolated Power Supply Voltages good with my digital multimeter.
Then I re-installed the IGBT POWER MODULE. Re-assembled the servo-drive and powered up the complete servo-drive good. The transformer re-wind was successful.