FANUC Alarm SRVO-062 — SERVO BZAL alarm

Description

This alarm is issued when the battery for backing up the absolute position data of the pulse coder is not connected. The battery cable inside the robot might have become disconnected.

Remedy

Correct the cause of the alarm, then turn on power again after setting the system variable $MCR.$SPC_RESET to TRUE. Master the robot.

Field diagnosis

The Pulsecoder absolute position backup is no longer powered: batteries empty or missing, battery cable broken inside the robot. The position is lost on the reported axis.

What to check

• Replace the batteries in the box at the robot base, check the battery cable up to the motor, then Pulsecoder reset (RES_PCA in MASTER/CAL or system variable), power cycle, and mastering (QUICK MASTER if the reference exists).
• If the alarm returns with new batteries: sagging contact springs in the battery box, then Pulsecoder.
• Note: Service observation: BZAL returned the day after a change to new batteries on an LR Mate/R-30iB Mate, cause = crushed battery holder springs; another case on R-30iA, a persistent BZAL on a single axis resolved by replacing the motor (the fault followed the motor, not the cable).
• Diagnostic sequence “Pulsecoder battery sequence”: Complete sequence after loss of position: BZAL (SRVO-062) at power-up, then 075 "position not established" after the encoder reset, then mastering. New batteries with the power on, Pulsecoder reset (RES_PCA or system variable), power cycle, QUICK MASTER if the reference exists (otherwise full mastering), jog of about ten degrees on each affected axis, RESET.
• Diagnostic sequence “Battery box / motor”: BZAL that returns after the batteries have been replaced: the message says "batteries", but the cause is not the battery. Discriminating test 1: battery box contact springs (sagged → no more contact despite good batteries). Discriminating test 2: swap the encoder cables of two axes and reset; if the fault follows the cable, it is the cable; if it stays on the axis, it is the encoder/motor.

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