Substituting Old Condensers With Modern Capacitors

[Mumbles]

The question keeps surfacing about what to do about old condensers which need replacing and are NLA. Well, a few years ago a club member went to great lengths to figure out which modern capacitors will work in our old magnetos. What he came up with was these Vishay axial capacitors available from Digi-Key and other electrical suppliers.

Here’s a few snips of the original post explaining the part numbering system.

Thanks again Jeff!

And here’s some links to Digi-Key for commonly used caps in 0.10, 0.15 and 0.22 uF ratings. You can choose your country in the top right corner.

https://www.digikey.ca/products/en?x=23&y=19&lang=en&site=ca&KeyWords=bc2607-nd

https://www.digikey.ca/products/en/capacitors/film-capacitors/62?k=bc2608-nd

https://www.digikey.ca/product-detail/en/vishay-bc-components/MKP1839422084HQ/BC2609-ND/2260507

Caps can be wired in parallel to arrive at the required uF (microfarad) rating for your motor. For example, if your mag need a cap rated at .30 uf, two .15’s can be used in parallel if a .30 cap is unavailable.

Vishay produces these caps with different voltage ratings but I’ve only used ones with an 850 volt rating. A smaller cap with a lower voltage rating might work to but I’m not sure.

• This topic was modified 6 years, 1 month ago by Mumbles.
• This topic was modified 6 years, 1 month ago by Mumbles.
• This topic was modified 6 years, 1 month ago by Mumbles.

[Mumbles]

And to help you choose which replacement cap to use in your oldie, here are some tables showing original uF ratings which another club member graciously compiled for us to use. Maybe Garry? Thanks!

• This reply was modified 6 years, 1 month ago by Mumbles.
• This reply was modified 6 years, 1 month ago by Mumbles.

[jeff-register]

Jim,
Remember speaking to Vishay & a requirement is ALL caps must be rated “High Quality’ HQ suffix to live in a mag. Still have the paperwork rat-holed somewhere!!
Jeff

[garry-in-michigan]

You’re welcome – I still haven’t found the value for the Evinrude Sportfour – Does anyone know ? ? ? [/size][/color]

• This reply was modified 6 years, 1 month ago by garry-in-michigan.

[jcrigan]

I found out today that the 400 volt caps don’t last very long in the Bendix Scintilla magnetos. Five minutes max.

[joecb]

It was through Jeff’s expertise that I and all of us realized that benefit of using these modern Vishay high quality capacitors in our motors. It was at least 3 or 4 years ago that he investigated the properties of the various modern cap and identifies the correct properties suitable for magneto service. I don’t begin to understand all the electronic specs ,but I remember that there was a lot mote to it than just the capacitance and voltage rating. Thanks Jeff

Joe B

[mercuryman]

How did the old condensers work so well. Just metal foil and paper rolled tight and stuffed in a can ?

[joecb]

The old caps worked just fine when they were new. Problem is that they have a shelf life, even when not in use. The paper and wax insulation breaks down and absorbs moisture over time. Just ask anyone that works on old radios or TV’s .. first thing that they have to do to bring an old set back to life is replace all the old caps.

Joe B

[chris-p]

Well my order of Vishay Caps came in today. I kept adding to cart to get it over 100USD to get free shipping. Should be good for Caps for a while.

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