Fanuc AC Axis Alarms. These alarms cover both faults and error codes on all analog (6050) and digital axis drives, VCU (velocity control units) and servo amplifier units (6057, 6058, 6066) pre ALPHA/BETA. The last two series being the S series and C series servo drives.

On 6050 and othersThese alarms are common too most series below.
TG (L/M/N)Tacho Generator LossIf the feedback cable is disconnected, TG lamp lights. If a motor does not make a speedy start because of extremely large motor torque.
HVHigh VoltageIf the DC voltage of the main power supply is abnormally high. The motor is stopped by dynamic braking with HV lamp lit.
LVLow VoltageLV occurs when the DC link voltage is excessively low or the regulator circuit has a malfunction.
HCHigh CurrentHC occurs when excessive current has crossed the DC link.
DCDischarge CircuitDC occurs when the capacity of the the discharge circuit has been exceeded.
OVCOvercurrent If current exceeding specified value is continuously applied longer than a certain time The motor is stopped by dynamic barking with OVC lamp lit.
On 6057/ 6058 SeriesAdditional Alarms listed on 6057/6058. Most alarms above are relevant
5VLow 5V5V indicates the state of power source applied on the board
DRDYReady StateDRDY indicates the ready state of servo servo amplifier.
OHOverheatOH occurs when a normally closed thermostat contact which is mounted either in the servo amplifier, on a separate discharge unit, or in a power transformer has opened.
FALIn case of fuse alarm NFB1-3 and trip of F4/F5.
6066 SeriesThis series has a 7 segment LED display with 1 alphanumeric character
1HVOvervoltage. If DC voltage of main circuit power supply is abnormally high, over voltage alarm occurs
2LV5VControl power supply undervoltage. Alarm occurs if control circuit power supply voltage (+5V) is abnormally low (LV5V Level: 4.6 VDC)
3LVDCDC Link undervoltage alarm.
4DCSWRegenerative control circuit abnormality.
5DCOHExcessive regerative discharge alarm.
8 / 9 / bHCM / HCLOvercurrent. Abnomally high current flows in main curcuits of L or/and M channels of the single or dual axis amplifier. Multiple causes.

Please contact us if you are unsure what your Fanuc AC Axis alarms mean or refer too. Of course call or email us if you need testing, repair or need an exchange part. Or please visit our dedicated Fanuc AC Axis drives or Fanuc Servo amplifier unit sections.