Fault Finding on Fanuc Alpha Servo Drives

Fault Finding on Fanuc Alpha Servo Amplifiers This information refers to the 6079/6080/6096 range of Fanuc Servo Drives A drive status alarm appears on the 7 segment display “-” refers to drive not ready (Waiting for an Emergency Stop signal to power up) “0” refers to drive powered up and OK Any other number or letter on this status display is an alarm A common fault is reporting an “8” alarm when the alarm is an “8.” ignoring or adding the full stop An “8” and an “8.” are different alarms (see below) This is also true for alarms “6” “6.”, “9” “9.” and “A” “A.”
Is the drive faulty? A List of Fanuc error codes can be found further down this blog

1 – Check the link (6079 drives only) A 6079 drive can give a fault if the S1 Link is in the wrong position S1 – JV Connections (Type A Interface) S2 – JS Connections (Type B Interface) An incorrect setting will cause an Alarm “8”

2 – Check the wiring is correct, L motor is wired in the lower terminals; M motor is wired in the upper terminals, both as U/V/W/E. JV1B connected from the L command plug of the axis card, JV2B from the M command plug. JX1A connected from previous drive, JX1B connected to the next drive in the line. The last drive in the line has a terminator in JX1B. 24v/0v/ESP connected into CX1A from the previous drive, out of CX1B to the next drive in the line.

3 – Disconnect Fanuc motor cable, Meggar the motor

4 – Power machine on whilst in emergency stop. The drive is faulty if an alarm occurs, expect “-” to be the norm.

5 – Release Emergency Stop and power the machine up If alarm occurs, power the machine off Remove motor wires U/V/W/E (Note – this is dangerous on a vertical axis, brake release, slide drops etc) Release Emergency Stop and power the machine up the drive is faulty if alarm occurs, expect “0”

6 – An additional test can be performed for equally sized 6079/6080 amplifiers H201 SVM2-12/12, H301 SVM2-12/12/12, H203 SVM2-20/20, H302 SVM3-12/12/20 (L&M), H206 SVM2-40/40, H303 SVM3-12/20/20 (M&N), H208 SVM2-80/80, H304 SVM3-20/20/20 (L/M&N). The suspect axis can be run from the other amplifier in the drive ie X drives M amplifier, Y drives L amplifier To do this swap round a – X & Y Motor cables U/V/W/E (at the drive) and b – X & Y Command cables (at the drive) (6096 requires parameters changing to swap X & Y round) The drive is faulty if the alarm remains the same as before the test, For example, Alarm “8” is reported on an A06B-6079-H201 drive using JV connections Steps 1~5 above, have been performed and still alarm “8” Remove the motor wires from the lower terminals and reconnect into the upper terminals, upper into lower. Remove JV1B and insert into JV2B, JV2B into JV1B. Retest the machine the drive is faulty if the same alarm occurs, ie alarm “8”. The fault lies elsewhere on the machine if another alarm occurs, ie alarm “9” In this example the drive has detected an overcurrent from the L axis, alarm “8” Swapping the cables over allowed a different amplifier to control the axis. An “8” alarm would remain if the same drive circuitry detected the overcurrent. A “9” would occur if the overcurrent was detected using the other drive circuitry in the amplifier and the fault would be caused externally from the drive.

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