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Craig Sawyers · 5th Feb 2023, 9:05 am

I use a Megohm meter. These were made identically by different manufacturers. AVO made one, and other manufacturers identical ones. 100, 250, 500 and 1000V. 10^5 to 10^11 ohms switchable.

The AVO one is the RM290, and the Sullivan one is T2900. Darned useful if you can find one. General Radio made one too - the 1862 and 1863.

Taking the example of a dreaded Hunts 350V paper cap. On a DVM it might measure fine. But put on one of the above meters, you get maybe 10^6 ohms at 100V and the meter might peg at 250V. on the 10^5 ohm range. So for those notorious parts the leakage is a strong function of applied DC voltage.

Craig

Craig

5th Feb 2023, 9:05 am	#20
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,991	Re: Testing for leaky caps I use a Megohm meter. These were made identically by different manufacturers. AVO made one, and other manufacturers identical ones. 100, 250, 500 and 1000V. 10^5 to 10^11 ohms switchable. The AVO one is the RM290, and the Sullivan one is T2900. Darned useful if you can find one. General Radio made one too - the 1862 and 1863. Taking the example of a dreaded Hunts 350V paper cap. On a DVM it might measure fine. But put on one of the above meters, you get maybe 10^6 ohms at 100V and the meter might peg at 250V. on the 10^5 ohm range. So for those notorious parts the leakage is a strong function of applied DC voltage. Craig Craig __________________ Doomed for a certain term to walk the night Last edited by Craig Sawyers; 5th Feb 2023 at 9:11 am.