Diagnosing A Spindle Drive Alarm - Okuma OSP 5000 Electrical Maintenance, Training Manual

In 1994, Okuma introduced the VAC III. The VAC III is very similar to the VAC II except for
its physical size. The VAC card I was incorporated into the VAC control board. The spindle
speed and position feedback are sent to the VAC control board (CN 2) where it is converted into
optical pulses and sent back to the SPC6 card. Like the BL IID axis drive amplifiers, the VAC
III utilizes IGBT's and hybrid IC's which have helped in reducing the physical size of this latest
Okuma spindle drive amplifier.
When the control receives an alarm signal from the spindle servo system, it generates a generic
alarm which the control sends to the CRT. This A level alarm is number 110 on lathes and 109
on machining centers. If this generic SDU alarm appears on the CRT, refer to the appropriate
maintenance manual to decipher the alarm condition.
The VAC has three operation status LED's labeled M1, M2, and M3 and thirteen numbered
status LED's on its control PCB. During normal operation, M1, M2, and M3 are off and the
thirteen status LED's show the status of the I/O signals on the VAC. In an alarm condition, the
on/off condition of these status LED's can mean different things depending on the on/off condi-
tion of the operation status LED's (M1, M2, and M3). The signal assignment of the status
LED's can be determined by looking in the maintenance manual.
The VAC II and VAC III spindle drive amplifiers do not use a generic SDU alarm. The A level
alarms associated with VAC II's and III's on lathes range from 1102 to 1142. On machining
centers these alarms range from 300-335. These two latest types of spindle drive amplifiers also
have two seven segment display LED's which show an alarm number. Again, the meaning of
these status LED's and alarm numbers can be deciphered by looking in the proper maintenance
manual.
Rev. 8-21-01

Diagnosing a spindle drive alarm.

Okuma America Corporation
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