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FANUC Controller
Spindle · Advanced · 30-90 minutes
Fanuc Alarm SP0753 - Spindle Position Sensor Error
Alarm SP0753 indicates the spindle control system has detected a fault in the position feedback signal from the spindle encoder or position coder used for spindle orientation (S-stop) or C-axis indexing/contouring. This typically results from encoder hardware failure, damaged encoder cable/connector, incorrect encoder power supply, or mismatched encoder interface parameters in the spindle amplifier or CNC.
SP0753
Fanuc Alarm SP0753 - Spindle Position Sensor Error
Spindle Position Error
Fanuc SP0753: Spindle Position Error. The spindle position has deviated beyond the allowable tolerance during position-controlled operation (orientation, rigid tapping, C-axis). The spindle position coder cannot maintain the commanded position.
Root Cause Summary
Alarm SP0753 indicates the spindle control system has detected a fault in the position feedback signal from the spindle encoder or position coder used for spindle orientation (S-stop) or C-axis indexing/contouring. This typically results from encoder hardware failure, damaged encoder cable/connector, incorrect encoder power supply, or mismatched encoder interface parameters in the spindle amplifier or CNC.
Safety
- Orientation may fail
Causes and Fixes
- 1
Check spindle amplifier LED status on the front panel. AL05 (encoder error) or AL06 (position error) LEDs indicate encoder circuit fault. Check for AL32 (encoder cable disconnection) on digital display if equipped.
- 2
Navigate to DIAGNOSIS > SPINDLE > screen and observe spindle encoder feedback (SPI/SPC actual position registers). Manually rotate spindle slowly; if position values do not change or are erratic, encoder signal is faulty.
Ensure spindle is in READY state and drive enabled before manual rotation test
- 3
Inspect encoder cable routing from spindle motor to amplifier JA6 or JA7 connector (depending on αi-SP amplifier model). Check for cable damage, contamination at connectors, or loose pins. Measure encoder cable shield continuity to PE ground.
- 4
If encoder cable is intact, check encoder power supply at spindle motor junction box. Verify +5VDC ±5% between encoder power pins (typically red/black wires). Low voltage indicates encoder power supply failure in amplifier or excessive cable resistance.
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