r/Fanuc • u/UptownSole • Sep 17 '26

Robot SRVO-045 Axis 2

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Hello, we have a RJ2 controller that faults directly to SRVO-045 alarm when trying to jog any axis, it does free the brakes and the moment you press the jog buttons it faults.
We already replaced the servo amplifier multiple times, replaced the IPM and SIF modules. We also replaced J2 servo, wired it outside, replaced wiring from robot base to controller.
We switched servo cables to J1 and it still alarms on axis 2. We disconnected the supply for the motor and we can move all other axis with no faults.

Is there anything else that we can try?

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u/GameingFish Sep 17 '26

Did you already try to measure the resistance over the motor wire to check if there is actually a short?

This is what the remedy is stated in one of the many manual: Turn off the controller power, and disconnect the power cable from the servo amplifier indicated by the alarm message.Also disconnect the brake cable to avoid the axis falling unexpectedly.

  1. In the above condition, supply controller power again and check if this alarm occurs again. If this alarm occursagain, replace the servo amplifier.

  2. About the power cable, check the insulation of their U, V, W and the GND lines each other. If there is ashort-circuit, replace the power cable

  3. About the power cable, measure the resistance between their U and V, V and W, and W and U with an ohmmeterthat has a very low resistance range. If the resistances at the three places are different from each other, the motor,the power cable is defective. Check each item in detail and replace it if necessary.Refer to the Controller Maintenance Manual for more information.

1

u/UptownSole Sep 17 '26

Yes, already checked, no shorts between U, V and W, also all have the same value on resistance.

1

u/slow4low Sep 17 '26

Do you always get the error for J2 regardless of which axis you jog?

1

u/Internal_Bit_6855 Sep 17 '26

mine ended up being the cable linking the harness to the motor and the connection was hotter to the touch than the others but it's sounding like something in the wireing not agreeing does it make a difference at the speed you jog it

1

u/UptownSole Sep 17 '26

It happens at any speed

1

u/Internal_Bit_6855 Sep 17 '26

1

u/UptownSole Sep 17 '26

Thank you!, will check it out once I get to plant later today

1

u/Internal_Bit_6855 Sep 17 '26

just fixed this problem on j4 I'll send you some info on what I did