SRVO-073: CMAL alarm (pulse coder noise/fault)
The encoder is misbehaving in a way that's either a real fault or electrical noise scrambling it - and FANUC's remedy list starts with grounding, which tells you noise is the frequent culprit.
What it means
The encoder is misbehaving in a way that's either a real fault or electrical noise scrambling it - and FANUC's remedy list starts with grounding, which tells you noise is the frequent culprit.
Common causes
Ranked by what technicians most often find, most likely first.
- Poor grounding letting noise corrupt the encoder (check the earth cable between controller and robot).
- Phantom alongside the SRVO-068/069/070 communication trio.
- Failed encoder, robot connection cable, or internal encoder/motor cable.
- On auxiliary axes: weak motor-flange grounding.
How to fix it
- Check the 068/069/070 trio in the history first.
- Verify the controller-to-robot earth connection is secure; on aux axes reinforce the motor flange ground.
- Then hardware in order: motor (re-master after), robot connection cable, internal robot cable.
- Recovery sequence after fixing the cause: PULSE RESET operation, then power cycle.