Maybe a dumb question, but as I am NOT an Electrical engineer….On those Vishay caps….is there a positive and negative side, or does it not matter?
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I also worked up some caps this past weekend.As far as the smaller square ones go,I used same method as Finn but used 18 gauge wire.I put some Vishay cylinder caps in some old caps as well.I used the taller old OMC condenser cans like the TD,HD etc used.Even though they are a little taller than the newer cans,I thing they will fit under the flywheel on the later models and mount the same way.
I too have bought the Vishay caps but never used yet. I’m going by the factory rep’s advice. true these caps were speced out to handle magneto voltages & not so much the envirement of an outboard. I’m sure potting compound would solve this issue. It is available at Digiking as well. Thank you everyone for your input!P.S. Olcah, I can see some of the issues in your install, The device needs to be mounted & the leads need to be insulated. In the past I have used oversized wire insulation as a covering around bare leads in radio work. Keep them from moving with a dab of super corona dope or any glue. I do know the caps are made a little big but are reliable replacement. Digiking is a distributer not a manufacturer. Hope this helps.
PS Bil,l Looked up the X7R cap at Digikey tonight, no longer availble, too bad.
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Well FWIW my experience with Digikey capacitors has not been that good. In short when installed bare they did not fit on the mag plate well. I used Digikey part BC2609-ND , Vishay MKP1839-HQ 220 n +-5%, 850V. I suspect the capacitor failed when running because I had bent the light wire excessively. Before the motor ran very well but skipped when the wire eventually broke. Motor is a 1956 Johnson 15 HP.
Had another failure with a 1956 Evinrude 15 HP. In short I was messing with the motor using starting fluid and got a large backfire. Bent even the linkage that rotates the mag plate. The cap was hit by the flywheel and torn away. I think the points fired when the capacitor was hit. I assume capacitor had shifted position as the motor had previously run ok.
Maybe someone can suggest an improvement in how I mounted the capacitor? The motors did run well with these caps.
Here is a photo of the caps installed on the mag plate. Ignore the 1st attachment. For some reason I can not edit it out
joecb
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Go with Jeff’s recommendation on the Vishay HQ caps I and others have used them and they do the job. The .22mf size will meet most all of your needs.
Joe B
John,
Looked up some data on caps for magnetos for you. Look up Digiking on the web, next go to Vishay 1832 caps. then go toMKP 1939422134HQ series. They are the best I found a few years ago, cost $4.33 each. & pick your required micro farad required. These caps will live in a magneto placement & some will fit in the cap shell. If anyone has a newer/better cap please help John or anyone else. Thanks for asking..
P.S. don’t forget the H.Q. at the end. “High Quality” for magnetos & look at data sheet for details 😉
Looked on the web under Nework electronics under MKP 1839433084HQ Nework part # 73R9945 & this cap model ranges from .1uf to 3.3uf with 850 volt rating & metaliszed. HQ must be part of the part number, means high quality & also shows factory spec sheet. Vishay has changed part numbers too.
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Look up MKP 1839hq on nework page.They show 10 different value caps!!
Mark,
I just deleted my post because it was already covered. I did some digging on capacitors & found some good data.
I ordered some Vishay brand capacitors from a electronics supply house. I also talked to a factory rep at the time & he said magneyos are hard on caps. He suggested an MKP=1839 for use. it is a .33 uf \15%\850volt capacitor for use. These capacitors are light years better than factory capacitors & will “live” in a magneto forever. They make many different uf sizes & order from an on-line electronics mail order supply house. You need a radial design also with leads coming out on either end to fit in your old capacitor case to look stock too.. Drill a small hole in the blank end then solder to the case & add the stock cap wire from the old junk cap & glue in place. Some capacitors are polorised, that is have a positive & negative symble C-I & nonpolarised I-I . You need nonpolrized type caps. Go to antiqueradioforums view topic-pleasehelpwill this capacitor work in a magneto? For more data. Hope this helps!
P.S. shipping is expensive so order a few extras, it costs the same Also try Nework electronics.com for mail order.
joecb
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From the referenced old thread, I posted on 3/18/2019 , the following. And I recall that Jeff Register had done extensive research on the subject.
“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
