1170

Common Causes

• Failed magnetic encoder or damaged encoder wiring
• Excessive gap between the magnetic encoder head and its gear
• Mismatch between the actual PG gear tooth count and the servo data file setting (e.g. after encoder or gear replacement)

Troubleshooting Steps

1. 1Read the code number shown with the alarm: code XXXX=A = A-phase voltage abnormal; YYYY shows the measured A-phase voltage; code XXXX=B = B-phase voltage abnormal; YYYY shows the measured B-phase voltage; code XXXX=C = Magnetic encoder data error; YYYY is fixed at 0; code XXXX=other = Servo data file set value (PG gear teeth x 4 - 1) at a count-over error; YYYY shows the actually detected count
2. 2Read the XXXX code: A means abnormal A-phase voltage, B means abnormal B-phase voltage, C means a magnetic encoder data error; any other value is the servo file set value (PG gear teeth x 4 - 1) captured when a count-over error occurred, with YYYY showing the actual detected count.
3. 3If XXXX is A or B, the phase voltage shown in YYYY is out of range - lock out the machine, then check the magnetic encoder wiring and connectors for opens, shorts, and coolant contamination.
4. 4Measure the air gap between the magnetic encoder head and the gear; if the encoder was recently disturbed or the gear replaced, re-set the gap to specification - a large gap causes weak/abnormal phase signals.
5. 5If XXXX is C or a count-over value, compare the actual gear tooth count on the machine against the tooth count data in the MCS servo data file; correct the file data or fit the correct gear/encoder so they match.
6. 6If wiring, gap, and tooth-count data are all correct, replace the magnetic encoder; if the alarm still returns, record the alarm number, object, and full code and contact Okuma service.