Skip to Content

Fanuc alarm 2 on main fanuc power supply that feeds axis drives - Fan alarm

Went in on a service call on a Fanuc based Mori Seiki CNC machine. The fanuc power supply had an alarm 2 displayed on it. The power supply feeds the other axis drives through the buss bars. The machine had an alarm as well for the axis drives.

To begin troubleshooting the machine alarms, fanuc refers you to some 400's diagnostics when looked up in the manual. Sorry do not remember off hand which one. When viewing them th FSA bit was a one for all axis drives powered by the power supply with the alarm 2. The FSA bit is a fan alarm.

After checking all the drive fans and ower supply fan. I found only the power supply fan seemed week.

I decided to pull out the fanuc power supply and disassemble to get at the fan. I found the bearings were shot in the fan. I had a new one on hand so I installed it. Put it all back together and tested. All good!

Main thing to gather from this is that most power supply alarms directly reflect problems within the power supply itself. The circuit must be designed to trigger all axis fan alarms when the fan is bad in the fanuc power supply.