hr(bob) wrote in message
...
On Apr 24, 5:39 am, "N_Cook" wrote:
A pensioner has asked me about possiblity of rewinding some of these
magneto
coils.http://home.graffiti.net/diverse:graffiti.net/K2F.jpg
laying on cm/mm graph paper.
Orangey section is the laquered coil.
C area is the contact patch (supplying 2 HT leads in turn) moulded into
the
surrounding paxolin? insulation, continued out to the boss marked P, but
otherwise looking like the tarnished brass sections in colour , marked B.
The curve above the C is the shape of one end of this contact section, not
a
trick of the light.
A is aluminium housing for the contact breaker
First comment is he has 5 of these , all not working at all or properly,
so
probably not good design anyway, as none were abused in use.
He has one good magneto , he moves around 3 bikes. He can get some or all
nonworkers commercially reconditioned , at a price each. But of course he
would like all 5 rewound and he knows, like me , that having researched
and
set-up for one then the following 4 rewinds are much easier. I use a
coil-winder machine but little experience of these sorts of coils.
No electrical data found on the net for these.
As received by me, the secondary measured 22K ohm, now reads 6.3K , at
this
stage, presumably shorted turns rather than a break for this one.
He has some sort of technical data for these , when he can find it, but
first thing is how to (after desolding) slide the laquered-in coil out of
the central section between the 2 steel pole pieces marked S, and because
of
the boss marked P that holds the HT wire lead out, coil would have to be
removed from the other open section, underneath in pic. Anyone know the
number of turns, wire gauge to save having to count off ? and details of
interlayer insulation (if any). How is the HT coil output removed from the
boss P or whereabouts is the join to a feedthrough under the output
laquer?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list
onhttp://home.graffiti.net/diverse:graffiti.net/

I hope you are either doing this as a HUGE favor for the pensioner, or
he/she is rich enough to pay you adequately for your time. No matter
how you get it apart, it will be a large royal pain to rewind with
that fine/small size wire and then reconnect the wire to the slip
rings. Any idea why so many of these hae failed, it might tell you
what not to do when rewinding.

I was quite happy putting on about 14,000 turns of 45 swg wire onto boat
outboard motor magneto coils, once the traverse rate, reducing
endstop/reversal points etc was set up for my 1920s coilwinder , rusted and
totally seized but now
rescued back into working order after decades in someone's damp and leaking
shed

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/