Alarm guide · Fanuc · Updated October 2026
Fanuc SV0364 alarm: soft phase alarm (pulsecoder)
Fanuc SV0364 is a soft phase alarm from the digital servo. It points to a problem in the pulsecoder data. The usual causes are a faulty pulsecoder, a damaged or noisy feedback cable, or a poor connection.
By Suresh Sankaran, founder of Star Automations, servo motor repair since 1998.
What the alarm means
The digital servo checks the phase data from the built-in pulsecoder. When the data does not match what the servo expects, it raises SV0364. The alarm text and numbers vary between CNC models, so confirm against the manual for your control.
Common causes
- Faulty or contaminated pulsecoder
- Damaged or loose feedback cable or connector
- Electrical noise or poor earthing
- Motor fault that disturbs the signal
Safe first checks
General guidance only. Follow the drive manual and your site's electrical safety rules. Power off, and let the DC bus discharge, before touching connectors.
- Power off and reseat the pulsecoder connector at the motor and the amplifier.
- Inspect the feedback cable for cuts, crushed sections and oil damage.
- Check earthing and keep the feedback cable away from power cables.
- Check the same axis on another motor or amplifier if your machine allows it.
When to send it for repair
Send the motor when the alarm follows the motor or stays with a good cable. The pulsecoder is tested, repaired or replaced, and aligned before the run test. Send the amplifier too if the alarm stays on the axis with a good motor.
See Fanuc servo motor repair, Fanuc pulsecoder repair and Fanuc servo amplifier repair.
Questions
Is SV0364 the same as SV0368?
No. SV0368 is a serial data error. Both involve the pulsecoder, so the checks are similar. See our SV0368 and SV0366 guide.
Is it the pulsecoder or the amplifier?
Swap the cable first, then test the motor on another axis if you can. If the alarm follows the motor, send the motor. We test both when you are not sure.
How long does repair take?
Emergency repair is done the same day where the fault and parts allow, urgent in 3 working days and standard in 7 working days, counted from when the unit reaches our bench and the quote is approved. Every unit returns with a printed test report.
Can I get an exchange unit?
If we hold a matching unit, Servo Swap ships a tested exchange unit while yours is repaired. Mark "line down" on the request form and add the part number.
Related: Fanuc SV0368 and SV0366 · SV0364 · SV0414 · Servo encoder alarms
Brand names identify the units we repair. Star Automations is an independent multi-brand repair company and is not an OEM service centre.