Intermittent alarms grind people down: clear it and it returns in days. This case walks the full reproduce-locate-replace-prevent loop - a standard sample for "comes and goes" faults.
A handling robot raised an encoder alarm once or twice a week; a reset cleared it and the line would not stop for an intermittent fault. The customer's electrician had checked connectors and battery - both fine.
Reproduce first: pull the axis pose from the alarm record, jog that axis to near the recorded pose by hand and measure encoder-cable continuity while moving - continuity flickered in one pose band. Reproduced. Then locate: the break sat about 20 cm inside the chain bend point; opening the jacket showed two fine cores fatigued through with the shield intact. Check the chain mileage: service age and takt put the bend count near design life.
Break inside the chain section plus bend count near life means, by our line, replace the whole encoder run - no joint. During the swap we also checked chain separators and internal burrs (one separator had shifted; reset), and the new cable got proper bend allowance with strain relief fixed at both ends.
Two months since the swap: zero recurrence. For prevention we started a chain "mileage" log for the customer - accumulated hours and takt on record, bend count estimated, replacement planned before end of life. The encoder cables on three same-age robots on the line joined the next service's inspection list.
