Express CNC Ltd 07976562067

2012 Express CNC Limited  Tel +44 (0)7976562067



Express CNC Limited - Specialist repairer of CNC Machine Tools
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Ajax, Bridgeport, Brother, Butler, Churchill, Colchester, Correa, Cincinnati, Daewoo, Dah Lih, DMG, Doosan, Emag, Emco, Feeler, Goratu, Geminis, Hartford, Hardinge, Harrison, Hitachi Seiki, Huron, Ikegai, Johnford, Kearns-Richards, Kia, Kitamura, Kuraki, Leadwell, Lagun, Makino, Matsuura, Mecof, Mori Seiki, Matrix, Nakamura, Nigata, OKK, Okuma, Star, Suga, Takisawa, Union, Victor, Wasino, Webster bennet, Yamazaki.

Fanuc, Heidenhain and Fagor CNC controls repaired FAST.

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Fanuc Alpha Servo drive alarms

Fanuc Servo amplifier Alarms


These alarms are found on the Fanuc Alpha servo drives, please check these alarms to enable us to complete a CNC repair to your machine tool quickly.


Alarm LED  display Likely Cause,  (for further information about these alarms please call or email us )


1  Inverter: internal cooling fan stopped

2  Inverter: control power supply under voltage

5  Inverter: DC link under voltage

6  Inverter: overheat

F  Inverter: cooling fan stopped of the radiator

P  Communication error between amplifier and module

8  Inverter: IPM alarm (L axis)

9  Inverter: IPM alarm (M axis)

A  Inverter: IPM alarm (N axis)

8  Inverter: IPM alarm (OH) (L axis)

9  Inverter: IPM alarm (OH) (M axis)

a  Inverter: IPM alarm (OH) (N axis)

b  Inverter: DC link current alarm (L axis)

c  Inverter: DC link current alarm (M axis)

D  Inverter: DC link current alarm (N axis)



For the older ac servo drives the alarm led lights on the servo PCB when in trouble. These alarms usually follow a 401 or 403 alarm on Fanuc system 0 controls and have the following meanings.

These alarms can also be checked in diagnostic 720-724 on system 0.

(The bits are referenced as 76543210)


OVL  Overload alarm    720-724 bit 7

LVAL  Low voltage alarm   720-724 bit 6

OVC  Over current alarm   720-724 bit 5

HCAL  high current alarm   720-724 bit 4

HVAL  High voltage alarm   720-724 bit 3

DCAL  DC alarm     720-724 bit 2

FBAL  A wire disconnection alarm   720-724 bit 1

OFAL  Overflow alarm    720-724 bit 0