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Old Oct 10, 2006, 07:13 PM
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GWS brushless speed control problem

I've got a SlowStick with a GWESC25A running a GWS/BLM-003 motor and GWS EP1047 prop and a 3S 1800mAh 11.1v LiPo battery pack. I've got a camera and some junk on there; so it's somewhat heavy for a SS, but gets around fine.

It's worked fine for a number of flights; but on the last flight, I flew for about 10 minutes or so, and while it was up pretty high, the prop quit. I figured I just killed the battery pack, so I dead-sticked it in with no problems. After it landed, I tried to start the prop by taking the radio down to zero throttle and back up, but got no response.
I put a fresh battery pack on, and now the prop will just jump and shake back and forth instead of spinning. After charging both packs, the response is the same with either. All the connections appear to be good, and the landing was smooth enough that I can't imagine damaging anything anyways.
Did I fry the speed control somehow?
Help!
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Old Oct 10, 2006, 07:20 PM
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Scoobyvroom's Avatar
Rockford, MN
Joined Jul 2003
450 Posts
Sounds to me like the motor is toast. IF the ESC had gone, you probably would have lost control of the plane. IE no power to the reciver. I would see about trying another motor. Also take a close look at the ESC and see if you can see balck residue on the inside of the wrapper. One last thing get your nose close to the ESC and take a whiff, burnt electronics have a smell to them..

Chris
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Old Oct 10, 2006, 09:45 PM
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Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
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You might have just lost a solder joint on one of the motor leads to the esc. They won't run on 2 out of 3 phases
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Old Oct 11, 2006, 03:23 AM
gws-online-dealer
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Winterthur, Switzerland
Joined Jan 2006
591 Posts
Yes, sounds like a missing or bad connection from one of the phases from ESC to motor. Maybe just as simple as a loose connector?
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Old Oct 11, 2006, 06:37 AM
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I can't see or smell and damage to the ESC; and all the connections seem to be secure.
If everybody thinks it's the motor, I guess the next step is to check resistance between all threee leads and see if I can find an open coil.
Are these little guys wye or delta? (or is there no correlation to industrial three-phase motors)
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Old Oct 11, 2006, 02:22 PM
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Darwin Australia
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Quote:
Originally Posted by ridefst
I can't see or smell and damage to the ESC; and all the connections seem to be secure.
If everybody thinks it's the motor, I guess the next step is to check resistance between all threee leads and see if I can find an open coil.
Are these little guys wye or delta? (or is there no correlation to industrial three-phase motors)
A solder joint can be mechanically secure but electrically bad. Did yoy solder plugs on yourself or were they soldered on when you got the motor.

Ken
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Old Oct 11, 2006, 05:49 PM
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SoCal, USA
Joined Jul 2006
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Quote:
Originally Posted by ridefst
I've got a SlowStick with a GWESC25A running a GWS/BLM-003 motor and GWS EP1047 prop and a 3S 1800mAh 11.1v LiPo battery pack. I've got a camera and some junk on there; so it's somewhat heavy for a SS, but gets around fine.

It's worked fine for a number of flights; but on the last flight, I flew for about 10 minutes or so, and while it was up pretty high, the prop quit. I figured I just killed the battery pack, so I dead-sticked it in with no problems. After it landed, I tried to start the prop by taking the radio down to zero throttle and back up, but got no response.
I put a fresh battery pack on, and now the prop will just jump and shake back and forth instead of spinning. After charging both packs, the response is the same with either. All the connections appear to be good, and the landing was smooth enough that I can't imagine damaging anything anyways.
Did I fry the speed control somehow?
Help!
I had a similar problem on another motor. I could never find the problem, but the ESC works fine on a different motor.
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Old Oct 14, 2006, 11:58 AM
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Taipei, Taiwan
Joined Oct 2005
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I'm afraid that the motor would probably get burnt in some degrees. Would you try to use another motor instead then to see if the new one works correctly for you.
If so, then the old motor would need to be further inspected.

Chen
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Old Oct 17, 2006, 08:24 PM
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Well, I've checked resistance between all three legs of the motor, and they all read the same, 1.1 Ohms.
I also tried to check the AC voltage out of the ESC; it shuts down pretty quickly when you throttle up with no motor hooked up, but I got readings of about 9.5VAC on all three legs there as well.
The ESC came with all wires and connections presoldered, though I'm pretty decent at soldering and can usually recognize and cold joint, these all look very nice.

Unfortunatly, this is my first electric airplane (slimer convert ) so I don't have an extra ESC or motor sitting around, so I'll have to go out and buy one or the other. I'm leaning towards the ESC at the moment; since I can't see how the motor could be damaged if the coils check out.

What do you guys think, have I checked everything there is to check?
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Old Oct 17, 2006, 09:17 PM
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SoCal, USA
Joined Jul 2006
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Did you check for a ground to the armature?

If only one spot on one wire touched the armature you won't get a short but you will disrupt the magnetic field of the motor. I think that was mine and your problem.
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Old Oct 17, 2006, 09:37 PM
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Quote:
Originally Posted by kcwannafly
Did you check for a ground to the armature?

If only one spot on one wire touched the armature you won't get a short but you will disrupt the magnetic field of the motor. I think that was mine and your problem.
Nice thought, so I checked, but no continuity to ground from any of the legs.
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Old Oct 18, 2006, 11:59 AM
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Ottawa, Canada
Joined Apr 2005
119 Posts
I would resolder all the leads from the motor to the conectors anyway, my 2208/18T came with very thin wires, (3 wires in parallel/phase) it's a delta connection. Could be that one of the wires in any of the fases does not have proper contact, it won't show in the ohmeter since it could be only one wire within one fase and you wouldn't notice. Just make sure you scrape well all the leads before soldering, that looks like a bad connection in one of the fases. I've had that problem before.
Another thing I could think of is ESC sync, I have a problem that my GWESC25A does not like speed under load, once it get to certain speed the motor starts screeching and the prop just turns in any direction back and forth. Run the motor with no prop on it and see what happens, then use a smaller prop to check again. If the motor runs fine with a smaller prop it could be ESC sync, if it doesn't run at all I go with a bad connection in one fase, if just one of the wires in one fase does not have the proper contact the motor won't run properly.
To solve the sync problem I had to advance the timing in the ESC using the GWS Programming Card to Medium Timing, and still sometimes when I apply full throttle quickly the motor quits.
Anyways I would still resolder all the wires properly, the wires are too thin, better yet if you can, re-wind the motor with a better wire using one thicker wire per fase.

I posted a video of what was happening to my motor here: http://www.rcgroups.com/forums/showthread.php?t=559826

Hope that helps
JR
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Old Oct 19, 2006, 07:49 PM
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Well, after looking at jreneponce's link; I realized that I could try an old CDROM motor with my ESC.
I ripped open an old drive that was lying around; soldered leads onto the motor; and it spins just fine.
I guess this means that there is something wrong with the motor (I have no idea what), but I'll be ordering a new one now.

Thanks for all the suggestions guys

Edit: I did try running my motor with no prop a while back, and that didn't work either...
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Old Oct 19, 2006, 08:20 PM
jreneponce's Avatar
Ottawa, Canada
Joined Apr 2005
119 Posts
Still I would think that one of the wires is broken somewhere, inside the leads most probably, that behaviour is classic of a broken wire in one of the fases, remove the heat shrink and the leads encapsulation and take a closer inspection, that's where they are more prone to break, I don't think they are broken in the windings itself although it could happen.
Just to make sure, desolder all the wires, carefully scrape the leads to remove the varnish and solder again, if they solder the connectors with the varnish on at least one of the wires it's going to be faulty.

regards
JR
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Old Oct 19, 2006, 08:45 PM
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Darwin Australia
Joined May 2002
6,960 Posts
The Varnish on magnet wire.

To make production easier the varnish on magnet wire breaks down at 350+ degrees tempreature when the wire is being soldered. At this temp the varnish does not inhibit the adhesion of solder to the wire.

In service the varnish is rated to provide insulation at up to 200 degrees.

So when you are soldering plugs to motor wires use a very hot soldering iron, preferably a tempreature controlled one dialed to about 375 deg. The joint should smoke as the varnish breaks down.

Ken
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