If anyone could provide some advice I would appreciate it very much.
I was given a Black and Decker electric mower. Model LM100 or possibly
LM106, hard to tell. When I try to run it it trips the breaker every
time. I took the cover off and checked the brushes. They are about 5/8th
of an inch long. When trying it with the cover off there is a lot of
sparking between each of the brushes and the armature? before it trips
the breaker. It sure looks like too much sparking to me, almost like a
dying out childs sparkler. It will run for 2 or 3 seconds before the
Any thought as to how I can repair it? Or any sites that I can be
pointed to that will help?
John.. Most likely a shorted armature. Check B & D web site and see if you
can determine cost of part. May not be worth repairing. All the B & D stuff
I have purchased had a short life, so I no longer buy there products..
Before you throw it out, check and see if you can take the motor itself in
somewhere and have it repaired. I'm talking about an outfit who's only
business is that of repairing electric motors. These places have all the
parts and tools necessary to rewind armatures, turn and true commutators,
fabricate new brush assemblies, replace motor bearings...the whole nine
yards. I've been able to resurrect a number of devices that use electric
motors that otherwise were candidates for the scrap heap by removing the
defective motor and simply taking the motor in to have it repaired.
I would at least look into this before throwing the mower away.
Just my .02 cents.
motor armatures were soaked in a special varnish. Then baked. This anchored
the windings so vibration would not allow the windings to rub and then short
to another wire. The cheap junk made now are just wound no varnish. Some do
not even have the wires anchored well at the termination to bars (where
brushes ride) so a lot of failures are due to a broken connection to the
bar. This will cause heavy arcing on the brushes. Warren
Many modern motors use bondable wire. An adhesive resin is applied
to the magnet wire at the manufacturer. After winding the wires are
heated and the wires are bonded to each other. This eliminates the
need to apply a varnish, epoxy, resin, etc., and also eliminates the
cure cycle for these materials.
Mike D suggested that I clean the armature. I'll give it a shot, thanks
Mike. But, I think Warren has got it right. There is one hell of a lot
of arcing at the brushes. Anyway, it was free so it can serve as an
education for me as I know so little about how electricity works.
Thanks for the thoughts everyone.
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