[Boatanchors] [Milsurplus] vintage motor winding question

[hwhall at compuserve.com]

Yes, it is an AC motor and the frame is like you described it.

I'd be willing to rewind from scratch if I could pull the bobbin, but the stator frame is riveted together. In the frame at either end of the winding bobbin, I can see gaps in each lamination, but only one per lamination (I've looked all over the frame for other gaps), and they alternate. I.e., the top lam shows a gap on the left side, the next lam shows a gap on the right, etc. So, I cannot see how they assembled it in the first place, or how I might pull the frame apart to remove the bobbin. Unless the "missing gaps" are hidden under the winding bobbin.
      
I've peeled 200 turns off & seem to be past the worst damage. I'm thinking I might be able to use a solenoid coil like a motor "growler". If I can put a mag field into the frame, a shorted turn might show by causing a hacksaw blade to vibrate if touched to the frame. At least, something like that is the theory for a real growler in a motor repair shop.

We may be able to locate another motor, but they are a limited commodity as you can appreciate. If we can learn to fix one, we may one day save a few more.
      
73,
      
Wayne
     WB4OGM 

 -----Original Message-----

From: J. Forster <jfor at quikus.com>
To: hwhall <hwhall at compuserve.com>
Cc: milsurplus <milsurplus at mailman.qth.net>; boatanchors <boatanchors at mailman.qth.net>
Sent: Wed, Sep 18, 2013 2:07 pm
Subject: Re: [Milsurplus] vintage motor winding question

I assume this is an AC motor? Is the winding basically a solenoid on a "C" 
shaped, laminated iron, core, with the motor armature in the gap of the 
"C"? 
 
Actually, it doesn't matter that much what the structure is. If a winding 
is burnt, it's finished. 
 
What happens is a few turns touch, the insulation fails, and you get 
shorted turns. 
 
The shorted turns act like a shorted transformer secondary and heat up. 
This promotes more failures and pretty soon the whole thing is toast. 
 
Aside: I've seen shorted turns causing a winding to glow dull red. 
 
Strip it all off and start new, IMO. 
 
-John 
 
=============== 
 
 
 
 
>  Hope this is not too far off topic. 
> 
> While working on a Link Trainer restoration, the winding on a simple small 
> shaded-pole motor went up in smoke. It's 1940-ish vintage and resembles 
> the traditional record-player motor or small desk fan motor. However, it 
> is not easily replaced by a modern motor due to parts of a gear train 
> being mounted on it. I'm peeling off turns hoping the damage is in top 
> layers and a partial rewind may repair it. 
> 
> My question is, when I think I've gotten past the burnt turns, and have DC 
> continuity through the winding again, is there a way to detect whether 
> there may be any shorted turns in the remaining part of the winding? All I 
> can think of right now is to see if it overheats rapidly. Is there 
> anything else to look for? 
> 
> TNX & 73, 
> 
> Wayne 
> WB4OGM 
> 
> 
> 
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