Bristol Digest, Vol 568, Issue 3

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Today's Topics:

1. Magneto Short Circuit Laminations - OT (Peter Hemmings)
2. Re: Magneto Short Circuit Laminations - OT (Dave Voorhis)
3. Re: Magneto Short Circuit Laminations - OT (Ian Plain)
4. Re: Magneto Short Circuit Laminations - OT - solved
(Peter Hemmings)
5. Re: South Wales LUG September 2014 Talks, 20th Sept, 1-4pm,
33 Winsor Place, Cardiff (Mark Einon)


----------------------------------------------------------------------

Message: 1
Date: Thu, 18 Sep 2014 14:07:08 +0100
From: Peter Hemmings <peter@hemmings.eclipse.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: [bristol] Magneto Short Circuit Laminations - OT
Message-ID: <541AD8FC.8000407@hemmings.eclipse.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

Hi,

I know there are some people as old as me on the list who also did
transformer theory at college and would appreciate confirmation on my
thoughts.

I have a VERY OLD (1950's) superb lawnmower that stopped sparking. I
did all the normal things, cleaned and reset points checked continuity,
checked and tried it without capacitor, Ooopps CONDENSER!

The magnets are still inside flywheel but still no spark.
Magneto is obsolete but found someone who fits new coil on armatures so
bit the bullet and paid ?65 for an exchange unit, which arrived this
morning. It looks like my old armature with new coil/capacitor fitted
but it dont work!

It is a VERY long time since I did transformed theory and I know the
Lamentations are insulated on on side and are used to stop eddy currents
and improve efficiency, but if some are shorted will that cause a failure?

FYI it just cut out when mowing the lawn and I am checking it with no
plug connector fitted!

Any pearls of wisdom gratefully accepted.


--
Peter H



------------------------------

Message: 2
Date: Thu, 18 Sep 2014 18:09:00 +0100
From: Dave Voorhis <dave@armchair.mb.ca>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Magneto Short Circuit Laminations - OT
Message-ID: <541B11AC.4090809@armchair.mb.ca>
Content-Type: text/plain; charset=windows-1252; format=flowed

On 18/09/14 14:07, Peter Hemmings wrote:
> Hi,
>
> I know there are some people as old as me on the list who also did
> transformer theory at college and would appreciate confirmation on my
> thoughts.
>
> I have a VERY OLD (1950's) superb lawnmower that stopped sparking. I
> did all the normal things, cleaned and reset points checked
> continuity, checked and tried it without capacitor, Ooopps CONDENSER!
>
> The magnets are still inside flywheel but still no spark.
> Magneto is obsolete but found someone who fits new coil on armatures
> so bit the bullet and paid ?65 for an exchange unit, which arrived
> this morning. It looks like my old armature with new coil/capacitor
> fitted but it dont work!
>
> It is a VERY long time since I did transformed theory and I know the
> Lamentations are insulated on on side and are used to stop eddy
> currents and improve efficiency, but if some are shorted will that
> cause a failure?
>
> FYI it just cut out when mowing the lawn and I am checking it with no
> plug connector fitted!
>
> Any pearls of wisdom gratefully accepted.
>
>

Is the points cam cast into the flywheel? If it's rotated on the
flywheel the points will no longer be synchronised with the magnets.

Have you verified the points are opening and closing correctly?

Have you verified that all wiring is sound and the insulation is
intact? Testing with an ohmmeter for shorts and opens is a good idea.

Is/are the magnet(s) still strong?

Replaced the condenser? They're rare these days, resulting in poor
quality replacements that are sometimes shorted or otherwise defective.

Shorted laminations shouldn't cause a problem.




------------------------------

Message: 3
Date: Thu, 18 Sep 2014 19:15:13 +0100
From: Ian Plain <ian@cyber-cottage.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Magneto Short Circuit Laminations - OT
Message-ID:
<CAPdamw-JSxMfFj4mwMQoW7KVvB4V2JkEEMMZXOhXusewON7PKw@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"

Have you thought of modding it to use a battery and transistor assisted
ignition ? Did this many years ago an Bantem that had a dud magneto
ignition. one charge should let you mow the lawn.

On 18 September 2014 14:07, Peter Hemmings <peter@hemmings.eclipse.co.uk>
wrote:

> Hi,
>
> I know there are some people as old as me on the list who also did
> transformer theory at college and would appreciate confirmation on my
> thoughts.
>
> I have a VERY OLD (1950's) superb lawnmower that stopped sparking. I did
> all the normal things, cleaned and reset points checked continuity,
> checked and tried it without capacitor, Ooopps CONDENSER!
>
> The magnets are still inside flywheel but still no spark.
> Magneto is obsolete but found someone who fits new coil on armatures so
> bit the bullet and paid ?65 for an exchange unit, which arrived this
> morning. It looks like my old armature with new coil/capacitor fitted but
> it dont work!
>
> It is a VERY long time since I did transformed theory and I know the
> Lamentations are insulated on on side and are used to stop eddy currents
> and improve efficiency, but if some are shorted will that cause a failure?
>
> FYI it just cut out when mowing the lawn and I am checking it with no plug
> connector fitted!
>
> Any pearls of wisdom gratefully accepted.
>
>
> --
> Peter H
>
> _______________________________________________
> Bristol mailing list
> Bristol@mailman.lug.org.uk
> https://mailman.lug.org.uk/mailman/listinfo/bristol
>



--
Thanks
Ian Plain
http://www.cyber-cottage.co.uk
Twitter @cyberco
Skype ba17sw
Ph: 01225580025
Txt: 01225580025

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------------------------------

Message: 4
Date: Thu, 18 Sep 2014 21:08:19 +0100
From: Peter Hemmings <peter@hemmings.eclipse.co.uk>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] Magneto Short Circuit Laminations - OT - solved
Message-ID: <541B3BB3.4020603@hemmings.eclipse.co.uk>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On checking again, I found the points were too wide! Reset and tried by
spinning by hand, still no spark. Almost gave up and decided to put it
all back and use pull cord for a bit more speed - and found a spark.
Filled carb with petrol and it worked!

The problem was turning speed and gap adjustment.

To give him credit the seller did suggest I gave it a quick spin with a
spanner or put the starter cord back and do it properly.


On 18/09/14 19:15, Ian Plain wrote:
> Have you thought of modding it to use a battery and transistor assisted
> ignition ?

Sounds interesting, I did convert my old car in the 70's before they
were common, 2 x 2n3055's as an invertor if I remember correctly!

Did this many years ago an Bantem that had a dud magneto
> ignition. one charge should let you mow the lawn.

FYI this magneto coil was also used on a Villiers engine!!

snip

Regards
--
Peter H



------------------------------

Message: 5
Date: Fri, 19 Sep 2014 11:42:21 +0100
From: Mark Einon <mark.einon@linux.com>
To: Bristol and Bath Linux User Group <bristol@mailman.lug.org.uk>
Subject: Re: [bristol] South Wales LUG September 2014 Talks, 20th
Sept, 1-4pm, 33 Winsor Place, Cardiff
Message-ID: <20140919104221.GA9568@leicester.auvation.com>
Content-Type: text/plain; charset=us-ascii

On Wed, Sep 17, 2014 at 11:32:24PM +0100, Karl wrote:
> Hey Mark,
>
> Unfortunately I can't make it, but at least 2 of the talks I'd be
> interested in hearing or checking out any slides on.
> Is there any possibility that it's going to be filmed or the
> speakers would be putting up their slides online later?

Hi Karl,

Unfortunately we're not going to be recording the talks, but the slides will certainly
be available afterwards - the links are normally posted on our mailing
list (see swlug.org, the last lot of slides from April are in the archives).

Cheers,

Mark



------------------------------

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End of Bristol Digest, Vol 568, Issue 3
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