Condensors

J

Jeff55B

Junior Member
I have inherited a Supco MFD-10 to test capacitors. What reading should I be looking for the signs that the condenser is good?
 
Great timing. I just received the same Honeytek A6013L yesterday, but even with the directions I am unclear on how to set it up.

Tom, where do you set the dial when testing a Model A condenser? Any other tips for the title of (EC), electrically challenged.
 
old31 said:
Great timing. I just received the same Honeytek A6013L yesterday, but even with the directions I am unclear on how to set it up.

Tom, where do you set the dial when testing a Model A condenser? Any other tips for the title of (EC), electrically challenged.
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Set the dial to the 12 O'clock position, straught up.
 
This is my practice:
 

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There is more to testing "caps" than measuring the capacitance. And I hope that someone with more electronic knowledge than I chimes in with more details. I have much experience with capacitors in small engine magneto applications. One can do a rudimentary test using a VOM ( volt Ohm Meter), but a cap that tests "good" may well fail in actual use because in use the cap is subject to a relatively high voltage surge ( in magneto application several hundred volts). I don't know the size of the surge in a battery ignition application, but I guess that it's considerably greater than battery voltage. If the insulation within the cap is weak that cap will fail in actual use.
Only way to be sure is to test on an instrument that subjects the cap to a high voltage, like a Mertronic or Stevens ignition tester.
Joe B
PS, as a side note, it is curious that . 22 micro farad (or there about !) is a common size for many many engine applications, small 4 cycles, outboards and Model A's
 
JoeCB said:
PS, as a side note, it is curious that . 22 micro farad (or there about !) is a common size for many many engine applications, small 4 cycles, outboards and Model A's
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It is curious but this may help.
The coil on small engines is usually located inside the flywheel along with the other ignition components. The coil is therefore limited in physical size. A coil of certain physical dimensions can only be designed to put out so much voltage and current.
These small engine all have approximately the same room inside the flywheel so the various coils and caps are similar in size.
A certain size coil will require a certain mfd. size capacitor. It is the inductance of the coil that determines this.

Capacitors can vary all over the place in size PHYSICALLY but still be made with the same capacitance.

A certain coil needs a certain capacitance to tune it to resonance. This results in a high impedance primary circuit which limits the average current so the points will live.
Electronic controlled primary circuits don't have points so the primary circuit can be designed to carry more current in the same physical space, thus hotter spark.
 
I've only tested a few dozen condensers, but it's been my experience that they tend to either pass all the tests or fail all the tests. I've had very few that pass the initial ambient temp capacitance test but then fail at high temperature.
 
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