The machine is a star sr32 with fanuc 16tt control. About 2 weeks ago, the machine began to give this alarm while it was booting up.

"750 Serial spindle link error" on HEAD 2.
later on after 10 seconds or so, it also gives the following -
401 X AXIS VREADY OFF -
401 Y AXIS VREADY OFF
401 Z AXIS VREADY OFF on head 1 and

401 X AXIS VREADY OFF
401 Z AXIS VREADY OFF on head 2.

I was simply turning off the machine, and power supply and turning them on again and alarm was going away easily.

But today, when i turn on the machine, the alarm condition became stable, whatever i did, i could not delete the alarm.

It also gives 19 on the led display of the spindle amplifier module.

I saw some advices the check optical cables? i do not know how and what to check..

Alarm Codes 19 and 20

The offset voltage of the phase U (alarm code 19) or phase V (alarm code
20) current detection circuit is excessively high. A check is made when the
power is turned on. If this alarm is issued, replace the SPM. If this alarm is issued
immediately after the SPM control printed circuit board is replaced, check the
plugging of the connectors between the power unit and SPM control printed
circuit board. ??

Anyone experienced before?