Code SP0086: Spindle sensor one-rotation signal not detected
Issue Description & Safety Warning
The Fanuc Alpha-i Servo Spindle Amplifier has triggered a critical Spindle sensor one-rotation signal not detected alarm. Immediate attention from a qualified operator or maintenance technician is required to prevent secondary damage to the equipment or spoiled parts during the manufacturing cycle. Always ensure standard safety and LOTO procedures are followed before accessing electrical cabinets.
Official Troubleshooting Steps
Amplifier LED display: 86 Also shown as: SP0086 (15i), SP9086 (30i/31i/32i), SP9086 (0i-D) Cause: (1) If the Spindle Amplifier status display is 4, 11, 30, 33, 51, 57, 58, b1, b2, or b3 This status display means that an alarm condition occurred in the Power Supply. Check the status display of the Power Supply, and see Section 2.3. (2) About CNC alarms 756 and 766 (abnormal axis number) These alarms can be issued only when the Dual Check Safety function is in use. If this alarm is issued, check that K76 shown below is attached to the JA7A connector of the second spindle. K76 is unnecessary if only the first spindle is used. If the wiring is normal, replace the Spindle Amplifier control printed-circuit board. SP (First spindle) CNC JA41 JA7B JA7A SP (Second spindle) JA7B K76 JA7A X2NDSP 0V (15) (13) K76 20-pin half-pitch connector Details of K76 3.TROUBLESHOOTING AND
Source: Fanuc αi Servo/Spindle Amplifier Maintenance Manual (B-65285EN/04) — Part II Troubleshooting
Last reviewed: 2026-07-01 · Verified against the manufacturer’s official documentation.
About Fanuc Alpha-i Servo Spindle Amplifier Alarms
Fanuc controllers include extensive self-diagnostics that flag or halt the machine when a fault is detected. Error code SP0086 on the Alpha-i Servo Spindle Amplifier identifies one specific fault condition — its documented cause and the official corrective steps are listed above, sourced from Fanuc's service documentation. Always confirm against the manual for your exact machine configuration and follow LOTO procedures before servicing.
Complete Alarm List: 135 Fanuc Alpha-i Servo Spindle Amplifier codes.
Have a better solution?
Help the industrial community by sharing your repair experience for code SP0086.
Need a searchable reference for more Fanuc Alpha-i Servo Spindle Amplifier manuals?
We structure equipment manuals into searchable code, title, cause, solution, safety note, and source-reference data. Send a PDF and example searched codes when you need public pages, private search, or structured exports.
Space reserved for Google AdSense / Industrial Affiliate Links
Monetization target for 2026