Thread: Condenser??

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A capacitor is comprised of two plates place next to each other with an insulator between them not allowing them to touch or make contact. Normally in operation one plates is charged by the voltage applied (usually positive) and the other plate charged with the mirror of the voltage applied (usually negative). This charging of the capacitor throws the current slightly ahead of the voltage, with breaker points this effect reduces the arching and heat as the points open. You could watch the points (with the cap off) while cranking the motor and see if the arch is centered on the points with a small focused arch (good condenser) or if the arch is larger and flashes outside of the points (bad condenser). Also note that a bad condenser will cause the points to burn quickly.

Using an ohm meter will sometimes work to test a capacitor, it uses the meter’s typical 9VDC to charge the capacitor’s plates with voltage (you’ll see the meter slightly move), then by reversing the meter’s leads it charges the capacitor with the opposite voltage (again, you’ll see the meter slightly move). If the meter pegs and stays there, the capacitor is shorted and needs replacing, shorted is the most common failure of a condenser (capacitor), however due motor vibrations an open capacitor is uncommon either. If the needle does not move when voltage is applied in either direction, the capacitor maybe to small for the meter’s sensitivity or open, an open capacitor usually caused by a bad internal connection (needs replacing).

Using a 9VDC meter will not always test for breakdown of the capacitors insulation, as the capacitor maybe operating at a higher voltage than the 9VDC supplied by the meter, however it is a good place to start.

Keep in mind that capacitors are rated by size (amount of storage) and voltage (maximum operating voltage) and temperature (maximum heat). If you changed your electrical system from 6 volt to 12 volt, and the condenser (capacitor) is not rated for the higher voltage it will probably fail and short. An electronic grade capacitor is usually not rated for the heat our motors develop and will usually fail.