Matronics Email Lists :: View topic - CJ Mag Coils

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

CJ Mag Coils - Test data required

Matronics Email Lists Forum Index -> Yak-List

View previous topic :: View next topic

Author Message

Harv

Joined: 01 Jul 2010
Posts: 170

Posted: Fri Jun 22, 2018 4:46 am Post subject: CJ Mag Coils - Test data required

Good morning all



I was hoping someone here might have test data for new (or could measure up a new coil) 'in spec' CJ6 coils?



I've been looking at my stumble issue on the Nanchang and removed both coils from the mags for bench testing both have been tested at ambient and then slow baked at 100deg for 60mins (I've no idea how hot they get in flight).

The primary's (thick windings) were tested with a ohm meter setting of 200 and gave the following:



Left mag at ambient = 00.5 ohm / Right mag at ambient = 00.5 ohm



Left mag at 100deg = 00.8 ohm / Right mag at 100deg = 0.007 ohm

The secondary side (thin windings with terminal sticking out of the core) were tested with an ohm meter setting of 20k and gave the following:



Left mag at ambient = 9.32 ohm / Right mag at ambient = 9.16 ohm



Left mag at 100deg = 11.96 ohm / Right mag at 100deg = 11.78 ohm

I'm not sure this really identifies anything, resistance increasing with temp as expected, they both have fairly similar readings at both temp extremes. 



One thing I did notice, with the right mag coil connector where the cigarette bears onto it in situ looks to be quite chaffed and I sometimes struggled to get a reading off it as if the face isn't conducting too well and it's also a little looser than the one on the left mag. If the cigarette was to loose momentary connection at the coil in flight would this contribute to the stumble? (I can accept the resulting engine shake at the point of the stumble may re-establish the connection)



Any ideas appreciated 



Cheers

Harv

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

GeorgeCoy

Joined: 02 Dec 2010
Posts: 308

Posted: Fri Jun 22, 2018 5:19 am Post subject: CJ Mag Coils - Test data required

As I recall, the capacitor is buried in the middle of the coil assembly. The

problem is usually the capacitor, not the windings breaking down.

George Coy



--

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

richard.goode(at)russiana
Guest

Posted: Fri Jun 22, 2018 6:00 am Post subject: CJ Mag Coils - Test data required

I agree with George - the problem is almost always the capacitor, and made

worse with heat. That is why the coils typically begin to break down after

20 minutes or so flight when the heat of the engine has soaked through to

the magneto. And of course having the capacitor inside the hot coil of wire

only makes the situation worse.



In England there are a number of companies working with old cars, many of

which have magnetos, and we have been in touch with the best ones to get

their advice. We decided on one particular company, who seemed very

knowledgeable, and for two years now they have been making new coils for us.

Of course they use the old coil former, but with better quality wiring.

However more important is the fact that they use a small Panasonic capacitor

which they bond to the outside of the coil, but in a way that makes no

difference to its installation in the magneto.



I should say that Aerometal, our partner in Hungary, have a high-temperature

test cell with a special test magneto, in which the temperature can be

elevated to well beyond any likely operating temperature. And we have found

that these new coils are very satisfactory, as well as producing a much

better spark and from much lower rpm than original coils.



Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW



Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com

--

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Harv

Joined: 01 Jul 2010
Posts: 170

Posted: Fri Jun 22, 2018 6:00 am Post subject: Re: CJ Mag Coils - Test data required

Thanks George



So lets assume my capacitor breaks down during my oven test at 100 deg, would that translate into something visible on the ohm meter during my test (for example open circuit?)



Tia

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

GeorgeCoy

Joined: 02 Dec 2010
Posts: 308

Posted: Fri Jun 22, 2018 6:30 am Post subject: CJ Mag Coils - Test data required

No, but it would cause timing problems a weaker spark and be very hard on

the points. 

George



--

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

justin76bd(at)gmail.com
Guest

Posted: Fri Jun 22, 2018 6:49 am Post subject: CJ Mag Coils - Test data required

test



[quote] On Jun 22, 2018, at 8:30 AM, George S. Coy <george.coy(at)gmail.com> wrote:

 

 

 

 No, but it would cause timing problems a weaker spark and be very hard on

 the points. 

 George

 

 --

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Harv

Joined: 01 Jul 2010
Posts: 170

Posted: Thu Jul 12, 2018 4:49 am Post subject: Re: CJ Mag Coils - Test data required

Just an update to complete this thread



Coils went off to a specialist firm who have been doing mag/coil winding for over 50 years. Their procedure is to heat soak, put them in a test rig and measure the output (there's also a set of points in the test which are set at 5.5mm). One had an output of nothing and the other produced a very weak spark so both items have been rebuilt.



Interestingly these are virtually identical to that used in a very old Bentley with slightly different specs which were established after dissecting.



Looking forward to getting the units back, fitted, and enjoying big fat sparks at the plugs for smooth running. Zero shelf time is a nice plus too.

- The Matronics Yak-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?Yak-List

Display posts from previous:

	Matronics Email Lists Forum Index -> Yak-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum