D4F1-27.0 
SYS_ALM412 CPU CORE VOLTAGE ALARM
MAINBOARD(CPU)

Video on Youtube

FANUC MD Main Unit Startup Error: Code 412

The root cause of the "412" error displayed upon startup of the FANUC MD main unit can be traced directly to the CPU.

Fault Description: This is a common issue with the FANUC MD main unit, occurring either sporadically or triggering immediately upon startup.
Repair Solution: The fault can be resolved simply by replacing the CPU. Replacing the CPU requires a reballing procedure; details on the reballing process can be found in the author's previous content.
Teardown Demonstration: After disassembling the unit in the video, internal components—such as the axis card, high-voltage board, and the CPU (equipped with a heatsink)—are displayed sequentially. The video clearly indicates the specific repair approach for this fault.

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