Coil Capacitor Testing - Tech Tip

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MKossor
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Joined: Sun Jan 06, 2019 7:30 pm
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Coil Capacitor Testing - Tech Tip

Post by MKossor » Sat Jul 31, 2021 1:55 am

Capacitor testing with the ECCT sometime produces a confusing result:
The correct capacitor Value is displayed BUT the Poor LED is illuminated?
So is the capacitor good or does it need to be replaced?
Cap Test Poor Leakage.JPG
Cap Test Poor Leakage.JPG (37.51 KiB) Viewed 1588 times
The capacitor is Good and does Not need to be replaced. Here's why.

Good capacitors have very low leakage current which translates to High Leakage Resistance, typically greater than 50,000,000 Ohms. So the Leakage Resistance test threshold was set much lower, to 5,000,000 Ohms

Many old coils may have degraded wire insulation, slightly conductive potting and/or conductive black paint on top of the coil which can cause higher leakage current that translates to Lower Leakage Resistance that is below the 5,000,000 Ohm Leakage Resistance test limit causing the Poor LED to be illuminated. That’s unfortunate because Leakage Current does not significantly affect coil performance unless it is very severe, well less than 1,000,000 Ohms. In hindsight, the capacitor Leakage Resistance test limit should have been set much lower to avoid confusion.

The bottom line is: Judge capacitors based on their Value, not Leakage Resistance. If the Capacitor Value tests greater than 0.33uF and less than 0.68uF it need not be replaced.

Cap Test Poor Leakage GUI.JPG
This capacitor is Good and does Not need to be replaced even though the Leakage Resistance Fails the 5,000,000 test limit.
I-Timer + ECCT Adjusted Coils = Best Model T Engine Performance Possible!
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Poppie
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Re: Coil Capacitor Testing - Tech Tip

Post by Poppie » Sat Jul 31, 2021 6:15 am

Haha, I now will be able to rest in Peace seeing that my repaired and adjusted HCCT trembler coils with correct value capacitors had failed under test with the Ecct are now OK, and I will not get stranded on the road somewhere.....n.


TXGOAT2
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Re: Coil Capacitor Testing - Tech Tip

Post by TXGOAT2 » Sat Jul 31, 2021 7:17 am

Could ambient humidity affect the reading?


Art M
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Re: Coil Capacitor Testing - Tech Tip

Post by Art M » Sat Jul 31, 2021 9:49 pm

Four years ago my son gave me a digital capacitor tester for Christmas. It is accurate and easy to use. I have replaced many coil capacitors. Every old coil that has not been apart has failed the test. I recommend to everyone who uses the original type coil to buy one. Probably have to order on line.
I am surprised that the various parts vendors don't handle them.
Art Mirtes

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