Thread: Condenser??

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Have a 51 ford I suspect the condenser faulty. I need to replace it. Anyone know the spec. I am in south Africa and have no chance of finding a parts supplier with any stock so I am hoping to get a comparable part from an electronics shop. Help please!

On my machine they test at .41-.44ish (less than .46) is presume it is in microfarads but it doesn't specify.

According to this spec site 1951 Ford 239 Flathead V8 Engine Specs the Condenser Capacity is 0.21-0.25 Mfds. Not sure why the difference from OJH's numbers, other than maybe system volts? Are you still running the 6V system?

Sorry guys this is now 12volt

You can check the condenser with a volt ohm meter, set it to the 200 ohm scale, put your leads on the condenser, one on the wire terminal the other to the case, and watch if the number rises. Once you reach overload, switch the meter leads and it should climb back down. If this does not occur, you have a bad condenser.

The condenser works like a muzzle flash suppressor, prevents the arcing as the points open and close.

Originally Posted by pepi

You can check the condenser with a volt ohm meter, set it to the 200 ohm scale, put your leads on the condenser, one on the wire terminal the other to the case, and watch if the number rises. Once you reach overload, switch the meter leads and it should climb back down. If this does not occur, you have a bad condenser.

The condenser works like a muzzle flash suppressor, prevents the arcing as the points open and close.

I'm ignorant of that test. Is this with the condenser loose (and discharged) on the bench, loading the capacitor with the VOM battery?

It is done with the part loose and yes to all the rest, it pretty well works on any cap or condenser, same parts.

Originally Posted by pepi

It is done with the part loose and yes to all the rest, it pretty well works on any cap or condenser, same parts.

Cool! Knew how the condenser/capacitor functioned, but not how to bench test them. Now if I can only remember the details.....

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.

Glad I could help, the scale will very with the size of the cap, they will either be shorted or open, mfds do not drift, except in a short .... then 0 ohms ..LL