E3LM Runs as a motor, almost no charge as a gen?

[Peter Gee]

Testing an old E3LM I imported from the states for an A10. Came straight out of a bike from a breaker yard.

Checked armature segments and got continuity/'beep' resistance on my so equipped voltmeter between a "master" segment and all others. Armature seems to have maybe had some overheating over about half its length as evidenced by one half or armature being very slightly blued in the  segments, vs the other half still normal copper colour...but maybe they all get like this after a lot of running.

(a) Joined F and D together

(b) Ran at  good RPM anti-clock  with an electric drill, got 0.4 volts

(c) My only 6v battery available being very old and worn out, used a  small 12volt battery to test as a motor. Negative to Dyno body, positive to  D or F ( joined together ) and very light touches to avoid burning anything. At once ran anti-clock as a generator.

What's likely wrong? My considerations are maybe  Re-cut the mica between armature segments?

[Rex]

That's something you don't want to start unless you really know what you're doing. Have you tried flashing it before you run it on the drill?

[Peter Gee]

Thanks Rex will try that tomorrow..I mean the brushes are ok, there seem to be no shorts..maybe it's just tired after many years idle..I am not sure they are rocket science!

[berger]

well all know about cutting between the segments is when my dad skimmed hundreds of armature comutaters and sleeved the shafts when bearings had seized. he used to scrape out between the segments to prevent shorting, I think he called it undercutting

[trevinoz]

I would say that your armature is buggered.
Most likely an open circuit in one or more coils.

[trevinoz]

Have a good look at the commutator segments.
Are there any with "flats"? That is a slightly depressed area the size of a brush. Caused by long periods of running with an open circuit.

Testing for continuity with a multi meter will not show an open generally as all of the 12 coils are connected in series via the comm. Trust me on this.
Another cause of your problem is high resistance between the brush and the comm. Give the comm a clean and wrap some abrasive paper around it and give the brushes a rub.
A generator with an open will motor quite happily at 6V but not so well at 2 - 4V.
A good one should motor at 2 - 3V.

[duTch]

 I had a similar issue with mine.
 I tracked down a shop with a growler and it showed a no-go (whatever they show), so swapped in another armature and achieved go-go. Frustrating when tests 'indicate' ok, but reality doesn't.