servo repair

[miljnor]

I have a Yaskawa Electric Ac servo motor part number SBMG-09A2AB serial number 7p1000 126-048

this is an 850watt ac servo from a vf-2 I am sick of paying HAAS 1200.00 for one and am looking for a servo repair place.

Does anyone have one they recomend and if so what service did you get from them and most importantly How much did your repair cost?

[miljnor]

anyone???

[Splint]

Have you investigated any motor rewinding services, they probably cant help you if the encoder is not working but they should be able to rebuild the motor side of things. Look in the yellow pages.

Splint

[miljnor]

even if they rewound the motor the encoder has to be lined up correctly.

If I could find information on DIY on the encoder I would get the motor rewound and line the dang encoder up myself. I believe it requires a Dual trace scope (which I have) and a little info. but am having trouble finding anything on it.

[Al_The_Man]

It is rare for AC servos to burn out due to current limiting in the amp etc, I have either found it to be the encoder or magnetization loss.
Fanuc AC motors are fairly easy to align as all you have to do is apply a DC voltage to the field to orient the armature and turn the encoder until a bit pattern is seen on the commutation signals, I would imagine yaskawa have a similar method.
Al.

[MoonlightMedia]

www.servotechusa.com/contact_servo.htm

I used to work for them repairing encoders. The guys
name is Michael Norman and they are very good at
what they do.

[miljnor]

Thanks Al,

What voltage should I apply to the feild to get it to orient (its a 200v servo) and I assume I have to power the encoder to get the commutation section to work?

And does it matter what commutation signal do I look for or does it matter. I know that the encoder can't be moved that far so its probably moot which one I am looking for as only one will go at a time. But it doesn't hurt to ask a professional.

And where would you get your replacement encoders from?

[Jonp]

can someone give me an idea of the process of alignment of a D C servo motor - encoder alignment, I'm pretty sure I have all the necessary equipment available , I'm just asking for the knowledge!! Thanks in advance for any information, Jon P.

[miljnor]

if its a brush dc motor it dosn't have an alignment. if its brushless I would assum you in the same boat as me.

[Al_The_Man]

For information in general about the relationship of Commutation signal to field the Renco site has a graphic display.
For the method I outlined for the Fanuc, two of the phases are connected together and high current DC is fed into the these and the other phase using a certain polarity, this orients the armature to the field, you would then need the manufacturers spec on what to see on the commutation signals, I imagine that Yaskawa maybe different from Fanuc as Fanuc use a uncommon 4 bit pattern output.
I have a previous post here outling the method with a scope and setting up a common point for the phases to align BLDC servos that use hall effect
commutation.
Unfortunately many large manuf. use unique mechanical and electronic characteristics for their encoders so you are generally forced to go back to them for replacements. Their are many companies that offere encoder repair but I have had mixed results with these.
Al.

[miljnor]

Al, could you post the renco link?


thanks

[DennisCNC]

There is a person that posted a few times in this servo section, he repairs AC servos. I remember he posted in a thread were some one was asking how to change the bearings on a AC servo.