Fanuc alarm 920: SERVO ALARM (1-4 AXIS)
system alarm · Fanuc 0i-D
What it means
Watchdog timer alarm or RAM parity error on the axis control LSI/card serving axes 1-4 (921 = axes 5-8)
Likely causes
- axis control card failure
- main board watchdog circuit fault
- +5V control supply droop
- servo amplifier pulling down shared bus
Triage note: If 920 appears together with an amplifier alarm, fix the drive first; isolated recurring 920 points at the main board
Replacement parts
We supply the following units for this alarm — tested, warranty-backed:
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A20B-8200-0740
Main CPU Board (0i-D, axis card integrated) · Primary suspect
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A06B-6130-H006
Power Supply Unit (beta i PSU) · Check if others ruled out
Need the part urgently?
Send us alarm 920 with your machine details — typical RFQ turnaround is 24–48h.