Alarm 56 Troubleshooting for FANUC CNC Spindle Amplifier

Alarm 56 Troubleshooting for FANUC CNC Spindle Amplifier

Spindle Amplifier Alarm 56
CNC Alarm SP9056
Applies to Alpha i Spindle

Alarm 56 on the Alpha i spindle amplifier indicates a failure of the internal cooling fan.

When the spindle amp faults out for a bad internal fan, it does it in two stages. When it first detects a fan problem, the amp goes into a warning state, and if the fan issue hasn’t self-corrected within one minute, it goes into an alarm state.

The word FAN flashes in the status bar when the CNC detects that a spindle amp is in the warning state.

While the spindle amplifier is in the warning state, the servo amplifiers are still powered up and able to move the machine around.

The SP 9056 alarm indicates that the amplifier has moved into the alarm state over the fan and all of the amplifier units immediately become NOT READY. (In parentheses it will state which spindle the amp controls – the one shown here is the only spindle on the machine)

The motor amplifiers tend to look very similar so you may want to access the electronics cabinet with power on (safely, of course) and look at the status displays of the units while the alarm is occurring. You’re looking for the unit that is displaying a 56.

The motor amplifiers are in the electrical cabinet and opening the cabinet with power applied potentially exposes you to danger.

In order to accurately troubleshoot the exact cause of this alarm, you will need to have power applied to the equipment. Don’t attempt to perform anything discussed in this presentation if you are not both fully qualified to do so and have the equipment owner’s permission to do so.

Once you are done troubleshooting and before performing any maintenance, follow all plant safety and lockout procedures. These procedures should include releasing all energies related to the maintenance procedure performed.

If you put your hand over the top of the spindle amplifier, you should feel air blowing on you. There may be another fan on the heatsink that is mounted through the wall, that has a different alarm.

If you don’t feel any air, you can be pretty confident in what the problem is. If you do feel air blowing, compare it to the other amplifiers in the machine, is it blowing just as hard?

FANUC has made the replacement of the fan easy. You don’t need to remove the amplifier, you don’t need any tools. If there is an object directly over the top of your amplifier, the story may change.

The latest series of amplifiers have a diagnostic that shows you the fan speed. CNC diagnostic 1723 reports the RPM reading of the fan, diagnostic 1724 is for larger amplifiers that have two internal fans. If you don’t have that diagnostic on your CNC, it just means your amplifiers are older models.

The internal cooling fan and its housing lift right off of the top and it goes back in the same way it came out.

In order to get the housing out, you must squeeze these two tabs to release it.

The fan and the housing are two seperate parts. The part number of the fan will probably start with A90L and chances are good the part number is printed on the fan. If it isn’t, contact our part sales department, give them the part number of your servo amplifier (it’s that A06B number on the label at the top of the amp) and they’ll figure it out.

The yellow plastic housing can be reused unless it’s physically damaged. Molded into the plastic you will find its part number – likely beginning with A230.

Now that you have the fan out, there are a few things that you can check for:

Is the fan physically blocked or filthy? Cleaning it up may fix it.

Try to reseat the fan module. perhaps it was a bad connection.

Is the plastic that holds the fan connector in place broken? Is it possible the fan isn’t plugging in to the amplifier correctly?

It is rare but sometimes it’s not the fan but the amplifier itself. The grey board that all the connectors plug into is removable from the amplifier. Try to reseat it. If you have other spindle amplifiers, see if they have the same circuit board by verifying the part numbers. If you’re comfortable, try swapping the boards.

If all of that fails, replace the fan.

Let us know if we can help. Call 888-326-8287, press 2 for CNC and then press 2 for technical support. To reach the part sales department, press 2 for CNC, then 1 and 1 again for part sales.
Alarm 56 Troubleshooting for FANUC CNC Spindle Amplifier



Alarm 56 Troubleshooting for FANUC CNC Spindle Amplifier