Very Informative Videos - Ignition Related

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Larry_G - 06/29/12 at 8:22pm

While searching for some Femsatronic CDI informaton, I found these very Informative Videos by accident. One of them shows just how fragile the insides of a Condenser is made. You will now know why Ignition Condensers fail over time with all the heat and stress cycles put on them. LG

http://www.youtube.com/watch?v=B6XepxHrQZg

http://www.youtube.com/watch?v=IqrWQRJQ ... re=related

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Bullfrog - 06/30/12 at 12:35am

The first guy missed an important factor about the internals of a condenser/capacitor . . . and almost missed another important detail.
1) The internals of a condenser contain TWO sheets of foil (this is the item the guy missed) which are . . .
2) . . . insulated from electrical contact with each other (the guy sort of, kind of, off-handedly mentioned insulation between the layers of foil).
IF the insulation breaks down and the two layers of foil become electrically connected, the condenser is no longer a condenser and ignition system no longer works.
The video does a decent job of showing that the internals of a condenser are delicate items. The foil is down in the "few thousandths of an inch in thickness" (maybe less) . . . and the insulation layer is also extremely thin (but must be faultless). So the internals are quite delicate -- which is why they are inside a sturdy steel can in a normal Hodie ignition system.
Ed

PS: In the past there has been a Hodaka fan who is experienced in basic electrics who has offered advice here. If I had more time I'd search out who that was and send an e-mail . . . but I don't have more time, so I'll just ask that person to contact me. I have had a "brain storm" regarding a simple to build tester for condensers involving a "double A" battery, a resistor of a specially calculated value, an LED and the condenser to be tested. I'm rusty on my Ohm's Law stuff, so please Mister Basic Electricity Wizard please contact me for a mini Research & Development confab.

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Larry_G - 07/01/12 at 3:03am

Yes; the video on the Condenser is pretty weak in the details/function. That is a lot of surface area/layers of foil and/or paper to go bad/burn. I bet the foil length is about 5 feet long if you were able to un-roll it?
Remember back in the early 1970's where many ads were posted in motorcycle related magazines for the Little Ignition Boxes.
These Magic Little Boxes were to replace the condenser and make your ignition points last way longer. I never tried one to see if the claims were true.
This was back when ignition points for Japanese Bikes were inexpensive and very available.
The onset of CDI Ignitions made them extinct.
On a related note; I think John Durill (sp?) AKA Sachs 175 is the person that posted a lot of informative electronic information on this Forum in the past. I am not sure if he is still an active member? LG

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thirdstone - 07/01/12 at 4:17am

Ed I don`t have a condenser to check out but simply its a capacitor. Big capacitors such as these can be checked in a basic fashion with an Ohm Meter. As you know Capacitors block DC and pass AC but a big capacitor will take a DC current until its charged up. If I had a condenser I could tell you how long is normal. Try this; Get a moving coil multimeter that has a 9V battery, LCD meters use button batteries and will not have the current to charge up a big capacitor. On the multimeter select the lowest resistance value to make the effect more visible eg: 0 to 10 OHM range. Put the leads on either end of the condenser and watch the meter. It should go from zero ohm to full scale high over a second or more, if its too fast select a higher range. This is the sign of a good condenser. If it stays on zero ohm then its short circuited ie the dielectric (insulation )has failed, throw it out. If it stays open circuit don`t throw it out , it could be your meter is not up to the job or the condenser has failed but if it fails in this way your ignition will still run as it wont be shorting to ground as its open circuit.Your points will pit pretty quickly and cause problems there. Another check worth doing is to make sure the input or ignition side lead is not shorted to the case. To check this put the tester lead on the case and one on the input lead. The meter should read open circuit or Meg Ohm.
I hope that helps
regards
Kev
P.S. some caps, such as Oil (dielectric) in paper/foil can dry out over a very long time and fail but apart from that they are pretty tough little critters.

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BrianZ - 07/01/12 at 8:12am

The condensers (capacitors) used in ignition systems are like Ed has already stated, 2 layers of foil separated by an insulator. They also contain an electrolyte (liquid) that increase their capacitance. They can fail in several different ways:
The first type of failure is a short circuit. This is caused when the internal insulation breaks down. Sometimes the insulation only breaks down when a certain voltage is reached, so the condenser will appear fine when checked with an ohmmeter but will not work in the ignition system. (You can also get a short across the top of the capacitor if it is dirty).
The second type of failure is an open circuit. This occurs when the connection to the internal foil breaks. The ignition system will function (not function) as if there is no condenser present.
The third type of failure is a reduction in capacitance. This occurs when the electrolyte dries up. The result is a reduction in performance of the ignition system.
Condensers are measure in Farads. I measured several condensers I have on hand and they all measured between 0.2 and 0.4 microfarads (millionths of a Farad). The variation in value is typical as tolerance on these parts is often +/- 50% or more! Most new multimeters have a capacitance setting that will allow you to measure condenser values.
Ed, I suspect you want to check the condenser by measuring its charge time with a resistor in series. A capacitor charges based on "time constant" = R X C. 1 time constant will charge the capacitor to 64% of it's maximum, and 2 time constants will charge it to 64% of it's maximum plus a further 64% of the remainder of the maximum for a total for 87%, etc, etc. Putting a 10 million ohm resistor in series with a condenser of 0.2 to 0.4 uF will produce a TC of 2-4 seconds.
Brian

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Bullfrog - 07/01/12 at 12:05pm

Actually, I was thinking of an oscillator circuit. If the LED flashes at somewhere near the right rate . . . the condenser is "good"???
Ed

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Larry_G - 07/01/12 at 12:07pm

Thanks Kev and Brian for you insight on how Condensers/Capacitors work and there construction methods.
Seems a lot of them fail when the engine heat peaks. And the main reason many relocate them away from the heat.
I think it would be a good idea to test/measure them Cold and Hot just to be sure. Using a hot air gun or hair dryer will come in handy.
Remember when we were kids and we would take the old condensers
our dads tossed during the car tune-up. We would remove the sparkplug cap from the minibike and have a friend crank the bike to charge-up the condenser. Then we would get someones sister, and say hold this. The effect was very shocking (pun intended).
This was before we knew what the real dangers of doing stupid stunts like this. Don't try it. LG

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Larry_G - 07/01/12 at 2:38pm

This is a Modern Day 12 Volt Box to replace your Ignition Condenser. http://www.hpi.be/mesonix.htm
This current unit reminds me of the of stuff they sold back in the day
but they were mostly made for 6 Volt Setups.
Link is for research/reference purposes only. No mention if they are intended for vintage street or enduro bikes using a 12 v battery or
common magneto type ignitions. LG

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