On 8/09/2018 6:20 AM, Bob Engelhardt wrote:
On 9/7/2018 3:49 PM, Dimitrij Klingbeil wrote:
Can you clarify if it's really an open commutator segment or an open
winding? These two are not the same thing.
You're right - I was sloppy in saying "winding", using the word as a
synonym for "segment".
Consider the commutator segments as follows:
... A B - D E F G H ...
Let's say segment "C" does not work. What does that really mean? Is "C"
completely disconnected or are there just different resistance values
when measured between B-C and C-D because one side winding is open?
My measure was that C was open; "infinite" resistance to everything.
You can also compare the resistance B-D to some other pair that spans
the same number of segments (like D-F, E-G, F-H).
If approximately R(B-D) = R(E-G) then the windings are intact, and only
the commutator segment has lost connection.
Clever - I wouldn't have thought of doing that.Â* I did do it and found
all the adjacent-by-2 resistances to be the same.Â* IOW, the windings are
intact, but not connected to this segment.
[...]
With this construction, if the winding is still good then so is the
piece of wire that goes to the non-working commutator segment, making
the (typically crimped) connection the most likely cause of failure.
If so, consider trying to reconnect the segment by e.g. removing some of
the lacquer and soldering through the badly crimped place rather that
trying to bridge the broken segment to a neighboring one.
[...]
The wiring end of the segment has a well with a slot & that suggests to
me that the winding is routed into the well through the slot & then a
plug is pressed in to connect and hold it:
https://imgur.com/a/XeQhLCw
I jammed a needle into the slot, hoping to make a connection to the
winding, but did not connect.
The windings at the back of the commutator are wrapped in string &
coated.Â* I'm thinking that I can cut back the string & get at the winding.
Thanks for your help.
Bob
Yeah that's the way to do it. A lot of times it's the crimp that has failed.