What's wrong with this AC Servo?

[Fit0]

Hi all,

So I made a cnc lathe (which I will introduce in a different thread) with a 750w Yaskawa AC servo and SGDA-08AP controller driving the spindle. After moving house, it sat unused for a few months. The other day, when setting the whole thing up again, the servo started making an awful grinding noise when turning the power on and throwing alarm A.70 (overload), even before running it. I'm scratching my head and wondering what the problem might be? A config problem, or something more serious?

Any help will be greatly appreciated - including a brief video and pics showing the issue.







Thanks everyone!

Fit0

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[Jim Dawson]

It almost sounds like the gain is set to high. Maybe try auto tuning and see if that fixes it.

[Fit0]

It almost sounds like the gain is set to high. Maybe try auto tuning and see if that fixes it.

Thanks Jim. Will autotuning work despite the alarm going off? Sorry if that's a silly question - servos are still a bit of a mystery to me.

[Jim Dawson]

You may have to do some adjusting, maybe set to factory defaults or something before autotuning. I don't know what adjustments are available in those units.

[mactec54]

You may have to do some adjusting, maybe set to factory defaults or something before autotuning. I don't know what adjustments are available in those units.

So how would you autotune a servo a motor with factory default, that is never going to work

They are the same to setup as any other servo drive just a lot more options / features than a lot of other servo drives others, but they don't take much to get running

[mactec54]

Hi all,

So I made a cnc lathe (which I will introduce in a different thread) with a 750w Yaskawa AC servo and SGDA-08AP controller driving the spindle. After moving house, it sat unused for a few months. The other day, when setting the whole thing up again, the servo started making an awful grinding noise when turning the power on and throwing alarm A.70 (overload), even before running it. I'm scratching my head and wondering what the problem might be? A config problem, or something more serious?

Any help will be greatly appreciated - including a brief video and pics showing the issue.







Thanks everyone!

Fit0

If you had it running before the move you should check your wiring Grounding and Encoder connections

[jittechnologies]

If you had it running before the move you should check your wiring Grounding and Encoder connections

^^^^^This... moving the machine shouldn't have affected the tuning... unless something mechanically changed. Did the drive retain the parameters you had in it? If so, check all your wiring, shielding, grounding, etc. Also, make sure your encoders, resolvers, hall effect devices, etc., are well connected. The "grinding" is oscillation.

Sent from my SM-N975U using Tapatalk

[Jim Dawson]

So how would you autotune a servo a motor with factory default, that is never going to work

They are the same to setup as any other servo drive just a lot more options / features than a lot of other servo drives others, but they don't take much to get running

Very insightful and helpful mactec54. Thank you for posting that.

[Fit0]

Very insightful and helpful mactec54. Thank you for posting that.

Thanks so much for helping me think this through the right way guys. As it turns out, the drive had lost the settings somehow (prolonged lack of use?) so I manually reset the user parameters as per the manual - and now we're back in business! Thanks again. Time to make some chips!