Another JM magneto resurrected

[Hugz]

Fared is the measure of capacitance. A capacitor and condensors is the same thing. Condensor is the old time description. A condensor stores electrical energy and then releases it. If you have 2 6 volt batteries you can join them to create 12volt. ie end to end. + to - to + to -.
I tried a few methods of testing but they didn't work. Personally I've never worried about testing them and only did so as you mentioned it. Good to learn.
Also if you measure the resistance across a condensor your meter will put out a small charge which then can be seen if you change the range to dc volts. Incidentally this is why you should never test the resistance of a car air bag as this small charge can explode the bag!

[Horsley-Anarak]

I get a bit lost with the condensers too. I've yet to have one fail.

All of the JM ones I have run on a boat have failed when they get hot, now I just replace them as a matter of course.

The engine will run perfectly on the test tank, but under load they fail after a few miles, the engine will not restart until it has cooled down.

I doubt that Villiers expected them to still be good after 70 to 80 years.

I just buy replacements on the Bay https://www.ebay.co.uk/itm/Villiers-M17 ... ctupt=true

[fleetingcontact]

So do these replacements also fit the Mk1?

[Horsley-Anarak]

So do these replacements also fit the Mk1?

Yep

[fleetingcontact]

Yep

Ta.

[AusAnzani]

This is a fantastic thread Hugo. Lots of great information. All very useful.

Thanks for sharing.

Regards,
Spiro

[AusAnzani]

PS: It would be nice if we could summarise and pin some of these tips so they are easy to find in future.