Servo running rough

matthewsx

matthewsx

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I bought one of these cheap sewing machine servo motors and it seemed fine for a short time then it started running rough at high speed.

flycut.jpeg

So I tore it apart expecting to find a bad bearing but the bearings seem tight and smooth. Now I'm wondering if it might be a problem with the cheap controller. I'm looking for a manual that might specify some kind of tuning operation or anything else that could help. This is the manufacturer but they don't seem to have any more info than the eBay seller.

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I'm pretty clueless on servo operation so anyone who might have insight into this would be appreciated.


John
 
Well, that was a short read but I'm no closer to understanding. Just in case someone else wants to check it out.

man.jpeg




man1.jpeg

These little motors are cheap and seem like they would be good for lots of different tool related uses. Just need to wrap my head around it enough to figure out if its broken or just needs tweaking.


John
 
More info! Is this a DC motor with brushes?
What if anything are you using for feed back?
Does the drive have a auto tune function?
Where is the gain set at?
 
I just put the 750 watt version on my drill press. So far it has run fine. I have the exact same manual and I have talked with the seller about some of the options. My guess is, you need a new controller, but you could try a factory reset of the controller and see what that gets you. There is a guy in Fl who has new boards for $50.
BEFORE you do this, make sure you know what P17 is set for. You will need to reset it. To enter programming, press P and S at the same time. Then browse up/down thru the functions.
See the first line under "Special Function" to do the reset.
Also, you might want to play with P6 and P8. I set them as low as possible. P8 set to 0 coasts to a stop and saves wear and tear.
Let me know if I can help.
Robert
 
Last edited:
Here is a cleaner version of the manual:
R
 

Attachments

  • Servo Motor Technician User Manual(v3.7 L-Type 4-Bar for ShuangZheng).pdf
    176 KB · Views: 28
I have another document that indicates that for the 550w motor p17 should be set to 8. I guess it depends on whether you have the 6 pole or 8 pole which you probably don't know. See how it is set now.
R
 
As far as I know that is a dc brushless motor which is a multiphase ac motor with a permanent magnet rotor. So the controller is actually a small VFD.
If it worked initially then the controller may have developed a malfunction. You might try contacting Pete at
www.olduhfguy.com and see if he can service them
Worst case try to get a replacement or get your money back thru your credit card company
-Mark
You would really need a scope to do any serious troubleshooting- and a schematic
 
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